Hobby Greenhouse Operations and Practices

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					                                        A L A B A M A   A & M   A N D   A U B U R N   U N I V E R S I T I E S

                                        Hobby Greenhouse
                                        Operations and Practices
Introduction                            The Plant Environment                gy for maintenance and growth
     Perhaps there is no greater                                             in a process called respiration.
                                            Even though a greenhouse
joy than owning a hobby green-                                               Photosynthesis and respiration
                                        is an enclosed space, it is not
house and entering a warm, dry                                               can be viewed as opposing
                                        isolated from the outside envi-
room filled with green plants                                                 processes, one capturing energy,
                                        ronment. Conditions within the
when there may be frost, wind,                                               the other using it. Plants must re-
                                        greenhouse are constantly
or rain outdoors. For many peo-                                              ceive enough light during the
                                        changing. Learn not only to see
ple, tending to a greenhouse is                                              day not only to meet the needs
                                        but also to feel changing condi-
like entering a relaxing, private                                            of maintenance but also to have
                                        tions. Watch weather forecasts
world, isolated from workaday                                                enough left over for growth.
                                        so that preemptive steps can be
worries as well as the weather.         taken to compensate for chang-            Every plant species has its
A greenhouse can be an absorb-          ing outside conditions. Day          own requirement for light inten-
ing hobby with the satisfaction         length, light intensity, tempera-    sity. Most vegetables, cut flow-
of growing fragrant flowering            ture, humidity, and precipitation    ers, and many flowering potted
plants, foliage plants, ingredients     frequency change hour to hour,       plants require high light intensity
for fresh-picked salads in winter,      day to day, and season to sea-       to grow well. Most foliage plants
transplants for the spring garden,      son. Greenhouse owners should        and some flowering potted
or bouquets of cut flowers.              be able to recognize these           plants require lower light intensi-
     Do not be fooled, however,         changes and alter environmental      ty to grow. Under light intensity
into believing that a hobby             control equipment to keep the        that is too low, plants exhibit
greenhouse does not involve             greenhouse environment opti-         slow growth, spindly, slender
some work. Constant attention           mum for plant growth.                elongated stems, yellow lower
is required at most times of the                                             leaves, and soft succulent
                                            Variations also exist within
year. This often means every day                                             growth. In some cases, they ex-
                                        a greenhouse. Look and feel for
during the summer unless auto-                                               hibit larger, thinner leaves and in
                                        patterns of light or shadow, low
matic watering and ventilation                                               others they exhibit smaller
                                        or high humidity, and stagnant
systems are installed. During the                                            leaves and stem bending toward
                                        or moving air. These patterns
year, there are always jobs to be                                            a light source (called phototro-
                                        create microclimate differences
done. But none of these chores                                               pism). Under light intensity that
                                        from the greenhouse center to
have to be strenuous or tedious                                              is too high, plants exhibit small-
                                        the walls. Take advantage of mi-
if tasks and the materials needed                                            er, light-green thick leaves, short
                                        croclimate differences by placing
to accomplish them are arranged                                              thick stems and, in extreme
                                        plants in areas within the green-
intelligently. The purpose of this                                           cases, burned leaf margins or
                                        house suitable for their growth.
publication is to provide infor-                                             scorched blotches on the leaves.
mation about tasks that should                                                    Light intensity in the green-
be done to have a well-run, effi-                                             house is measured in foot can-
cient hobby greenhouse, one                 During the day, leaves of        dles (f.c.). A clear summer day
that is satisfying for the owner        plants use the energy from sun-      may measure 10,000 f.c., while
and a joy for the entire family.        light combined with carbon           an overcast, winter day may
Information on hobby green-             dioxide from the air and water       measure 500 f.c. The amount of
house construction and environ-         from the soil to manufacture         light needed for a person to read
mental maintenance equipment            sugar and oxygen in a process        comfortably is about 20 f.c.,
can be found in Extension publi-        called photosynthesis. At night,     while the light of a full moon is
cation ANR-1105, “Hobby                 plants burn sugar produced dur-      less than 1 f.c. Measuring the
Greenhouse Construction.”               ing the day and release the ener-    light available to plants requires

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a simple, convenient tool called      is diluted and sprayed on the         Temperature
a light meter. It is the only way     outside of the glazing. It is often        Each plant species has an
to be sure plants are receiving       applied in two applications, one      optimum and tolerable tempera-
the correct amount of light. Light    light application in mid to late      ture range for growth. Plant
meters can be purchased from          March and a second application        growth and flowering are rapid
greenhouse supply companies           in mid to late April. Shade paint     within the optimum temperature
for $70 to $120. Recommended          is designed to weather off the        range. Tolerable temperatures,
light intensity ranges for specific    glazing gradually over the sum-       which may be higher or lower
plants can be found in books          mer and fall. However, it is fre-     than optimum, allow the plant to
under the additional reading sec-     quently necessary to wash the         grow but at a reduced rate.
tion of this publication.             glazing in late fall with soap and    Growth usually stops and plants
     The purpose of glazing (the      water and a long-handled brush        may be damaged at tempera-
transparent or translucent materi-    to prevent unwanted light reduc-      tures outside the tolerable range.
al such as glass covering a           tion in the winter.                   Recommended growing temper-
greenhouse) is to capture sun-             Greenhouse blinds are re-        atures can be found in books
light as well as to separate the      garded by many owners as the          such as those listed under the
interior greenhouse environment       best shading alternative. Blinds      additional reading section of this
from the outside environment.         can be purchased in a wide se-        publication. Generally, these rec-
During the summer, high light         lection of roller types made with     ommendations are for minimum
intensity can burn low-light re-      wood, plastic, or plastic-coated      night temperatures because heat-
quiring plants and raise interior     aluminum slats. Many owners           ing is required to maintain a
temperatures excessively. Light       mount blinds on the outside of        minimum temperature for
intensity and heat load in the        the greenhouse that aid in heat       growth.
greenhouse can be reduced             reduction but like shade fabric            Most plant species grown in
using one of several means of         can interfere with vent opera-        greenhouses are tropical or sub-
shading.                              tion. Blinds designed to be           tropical in origin and heating,
     Shade fabric is a woven          mounted inside the greenhouse         when needed, to a 60 to 65 de-
polyethylene cloth that can be        can be adjustable.                    grees F minimum night tempera-
purchased from greenhouse sup-             Most methods for increasing      ture works well. Exceptions to
ply companies. It comes in            light intensity after a greenhouse    this recommendation include
weave densities ranging from 20       is constructed are drastic, such      many cool-season plants such as
to 90 percent. It is more effective   as cutting down trees or remov-       primula, pansy, and some or-
in heat reduction to purchase a       ing other outdoor obstacles, or       chids. Cooler than optimum
size large enough to drape over       expensive, such as installing arti-   night temperatures will slow
the outside of the greenhouse         ficial light sources. However,         growth while warmer tempera-
rather than hanging the fabric in-    plants can be spaced farther          tures will speed growth. Daytime
side. One problem with draping        apart and objects such as hang-       temperature should generally be
fabric over the outside of the        ing baskets can be taken down         5 to 10 degrees F warmer on
greenhouse, however, is that it       in the winter to reduce competi-      cloudy days and 10 to 15 de-
can interfere with vent opera-        tion and shading. Painting as         grees F warmer on sunny days
tion. During the summer in            many interior surfaces as possi-      than the night temperature.
Alabama, high light requiring         ble with white semigloss or gloss     Excessively warm temperatures
plants can benefit from 30 to 40       paint can also increase light in-     during the day or night, espe-
percent shade while low light re-     tensity. Exterior latex works well    cially during cloudy weather, can
quiring plants may need 50 to 80      but epoxy paint is even better.       reduce growth because respira-
percent shade. Purchase shade         Paint benches, walls, doors,          tion is increased and plants use
fabric with grommets along the        glazing supports, and even the        sugars faster than photosynthesis
edges so the cloth can be tied        floor, if possible, to reflect light.   can manufacture them.
down in case of strong wind.          Another solution is to use a her-          Temperature requirements
     One simple and inexpensive       bicide to kill all vegetation with-   can also change with a plant’s
alternative is to purchase shade      in 10 to 15 feet around the out-      stage of growth. Generally, ger-
paint from a greenhouse supply        side of the greenhouse and to         minating seed and seedlings and
company. Mix the paint with           spread white rock on the outside      rooting vegetative cuttings re-
water according to the manufac-       to reflect light into the green-       quire warmer temperatures,
turer’s directions. Shade paint is    house.                                plants growing vegetatively per-
a weak- binding latex paint that                                            form better under somewhat

2 Alabama Cooperative Extension System
cooler temperatures, and flower-      leaves, require watering more        side air, then allow the heating
ing plants need under even cool-     frequently, or develop burned        system to warm the air to its set
er temperatures. With a mix of       leaf margins or leaf tips. Plants    point, thereby reducing the
plants at different stages of        growing at RH above 85 percent       amount of water in the green-
growth in the greenhouse, it         are susceptible to fungal            house air. Ironically, high RH
may be difficult to select an         pathogens, especially if water       and condensation are generally
ideal temperature; nonetheless,      condenses on the foliage.            not a problem during the cold of
provision should be made for             Several conditions can occur     winter because heating reduces
germinating seed and rooting         in a greenhouse that result in       the amount of water in the air.
cuttings in a warmer setting.        problems caused by high or low
    Greenhouse temperature           RH. During the summer, high          The Root Environment
maintenance equipment (fans,         light, high temperature, and             Underneath every healthy
heaters, etc.) is commonly regu-     rapid air movement from fans         plant is a healthy root system.
lated by installing one to several   can reduce RH to unacceptable        Although most of us know what
thermostats depending on the         levels. Shading to reduce light      a healthy plant looks like, few of
number of devices that require       and temperature and using evap-      us bother to learn what healthy
control. Thermostats controlling     orative cooling (cooling pads)       roots look like. Learning the
heating equipment are set to the     are the best solutions. RH can be    characteristics of healthy roots is
minimum desired temperature          raised for a short time by using a   one key to successful growing
and cooling devices are set to       hose to wet down interior sur-       and diagnosing of plant prob-
the maximum desired tempera-         faces (walks, side walls, and        lems. Drop plants out of their
ture. Do not depend, however,        open bench areas, but not            pots periodically and examine
on the accuracy of commercial        plants). It is also advisable to     the roots. Roots may be thin, fi-
thermostats. Instead, install a      keep the greenhouse full of          brous, and many-branched or
high/low thermometer next to         plants because plants generate a     thick and straight with few
the thermostats and adjust the       lot of RH.                           branches depending on the plant
thermostat set points according          During the spring and fall,      species. However, they should
to the high/low thermometer.         warm days followed by cool,          be more or less white, not
High/low thermometers record         clear nights cause rapid heat loss   brown or black. There should be
the low temperature at night and     from the greenhouse, especially      root hair development just be-
the high temperature during the      from the glazing material. Warm,     hind the root tip. Root hairs
day. They have two liquid-filled      moist interior air moving next to    should be straight, not curled,
glass stems and a metal bar          cool glazing material can drop to    discolored or absent. Roots
within the glass stems that          the dew point temperature and        should grow toward the bottom
moves as the temperature             cause water to condense in           of the pot and, when mature,
changes, but stays in place at the   droplets on the inside of the        cover the entire soil volume.
lowest and highest temperature       glazing material. These droplets     Disease, incorrect watering prac-
readings. Record the tempera-        run down the slope of the roof,      tices, poor soil, excessive fertiliz-
tures and reset the high/low         grow larger, and then rain down      er, or a combination of these fac-
thermometer daily. The ther-         on plants below creating ideal       tors can cause root problems.
mometer is reset by moving the       conditions for the growth of fun-
metal bars with a magnet or by       gal pathogens. Two ways to re-       Potting Soil
pressing a button on the face of     duce this problem is to avoid
the thermometer.                     watering plants late in the day          The major function of pot-
                                     and to make sure the green-          ting soil is to provide air (oxy-
Relative Humidity                    house floor drains well with no       gen and carbon dioxide), plant
                                     standing water or constant wet       support, and a constant supply
     Relative humidity (RH) is a                                          of water and fertilizer nutrients
measure of how much water is         spots. The best way, however, to
                                     alleviate this problem is to wire    to the roots. Roots take up oxy-
dissolved in the air at a particu-                                        gen and give off carbon dioxide
lar temperature expressed as a       a fan to a 24-hour time clock
                                     and set the fan to turn on for 30    in respiration to carry out their
percentage. Generally, growth of                                          functions. Therefore, potting soil
many plants is relatively unaf-      to 60 minutes (depending on the
                                     size of the greenhouse) starting     must have a sufficient number of
fected by RH between 45 per-                                              large channels or pores to allow
cent and 85 percent. Plants          at 9:00 or 10:00 PM. The goal is
                                     to exchange the warm, moist in-      water to move through quickly
growing at RH below 45 percent                                            and to allow air to exchange
may grow slowly, have smaller        terior air with cool, moist out-
                                                                          with the atmosphere. It should

                                                                 Hobby Greenhouse Operations and Practices   3
also have a sufficient number of        or composted byproducts (leaf            start, but additional fertilizer will
small pores to hold adequate           mold, sewage sludge, etc.) can           be needed once plants establish.
water and fertilizer between ap-       also be used. The drainage com-               Four cubic feet is a conve-
plications. In addition, potting       ponent improves the potting              nient amount of potting soil to
soil should be initially low in fer-   soil’s ability to drain water and        mix at a time. This amount will
tilizer, free from toxins or herbi-    exchange oxygen and carbon               fit into a 30-gallon, new or clean
cides, standardized and uniform        dioxide with the air. Perlite and        garbage can for storage and will
for consistent results, and free       vermiculite are widely used, but         fill approximately 171 4-inch
from diseases, insects, and weed       sand (washed river sand) can             pots, 93 5-inch pots, or 56 6-inch
seed. Soil from the yard cannot        also be used. Chemical additives         pots. Begin by constructing a
meet many of these criteria, es-       can be blended in the potting            box from plywood with a 1-
pecially once confined to a pot.        soil when the organic and                cubic foot inside dimension.
Therefore, it should not be used       drainage components are mixed.           Measure the organic and
in a potting soil for the green-            The pH of a potting soil is a       drainage ingredients according
house.                                 measure of the acidity or alkalin-       to Table 1 and mix them with a
     Most of the potting soils used    ity of the mix. The pH scale             shovel on a clean surface to pre-
in greenhouse growing are called       ranges from 1 to 14 with 7 being         vent contamination by root
soilless mixes. As the name im-        neutral. Kits or meters for testing      pathogens (cover dirty surfaces
plies, they do not contain soil        potting media pH can be pur-             with plastic). Add just enough
from the ground. There are two         chased from garden centers or            water to the mix to barely dark-
choices for obtaining sufficient        greenhouse supply catalogs.              en the color. Turn the soil as
potting soil, either mix your own      Most plants grow well in a soil-         you add water. Measure the fer-
or purchase it commercially al-        less potting soil with a 5.5 to 6.5      tilizer and limestone using an ac-
ready prepared in bags from re-        pH. However, a potting soil              curate scale and mix them to-
tail sources. Commercial potting       using peat moss as an organic            gether in a bucket. Add some of
soil is convenient and inexpen-        component will have an unac-             the fertilizer/limestone mix and
sive, but unfortunately, no stan-      ceptably low pH. Dolomitic               turn the soil, repeat until all the
dards exist for content or quality.    limestone, which also supplies           fertilizer/limestone mix is uni-
There may be a high variation          calcium and magnesium needed             formly blended.
among brands. Look for a brand         for plant growth, is added to the
with “Professional Potting Mix”        potting soil at the time of mixing       Watering
on the label, then look for a list     to raise the pH. It is both conve-
                                                                                     Miswatering, typically over-
of contents. The potting mix           nient and economical to add
                                                                                watering, is probably one of the
should contain predominately           some fertilizer to the soil at the
                                                                                major causes of failure with
peat moss, perlite, and/or vermi-      time of mixing. Superphosphate
                                                                                plants in a greenhouse. Despite
culite. Run a test in your green-      (rock phosphate), a commercial
                                                                                all that has been written, water-
house with several brands using        micronutrient formulation and a
                                                                                ing plants comes down to two
different plants to see which one      source of nitrogen and potassi-
                                                                                critical decisions: when to water
performs best. The advantage of        um can be added at mixing.
                                                                                and how much to apply at a
mixing your own potting soil is        Keep in mind that these rates
                                                                                time. How much water to apply
that you have control over the         will get plants off to a good
                                                                                at a time is relatively easy as
content and quality. Recipes for
                                                                                long as plants are growing in
three soilless potting soils are
found in Table 1. Ingredients for      Table 1. Three Soilless Potting Soils for Hobby Greenhouse Culture
mixing your own potting soil can
                                       Type             Ingredient                       per 1 cu. yd. per 4 cu. ft.
be purchased from garden cen-
ters or greenhouse supply cata-                         Peat moss (50 percent)           131⁄ 2 cu.ft   2 cu.ft.
logs.                                  High moisture    Vermiculite (50 percent)*        131⁄ 2 cu.ft.  2 cu.ft.
     Soilless mixes are composed       High drainage    Perlite (50 percent) OR          131⁄ 2 cu.ft.  2 cu.ft.
of two categories of compo-            Intermediate     Vermiculite (25 percent) *       6: cu.ft. each 1 cu.ft.
nents. The organic component                            + Perlite (25 percent)                          each
gives potting soil the ability to                       Dolomitic limestone (ground) 8 to 10 lb.        19 to 24 oz.
absorb large amounts of water                           Superphosphate (0-20-0)          2 lb.          5 oz.
and fertilizer. Peat moss is used                       Potassium nitrate (13-0-45)      1 lb.          21⁄ 2 oz.
more than any other organic
component, but composted bark                          Minor elements (manufacturer recommendations)
                                       *Medium or coarse grade

4 Alabama Cooperative Extension System
well-drained potting soil. Apply      end to soften the flow water im-       on the front label. When shop-
an amount of water that will sat-     pacting the soil surface. A one-      ping for a fertilizer, purchase a
urate the entire soil volume in the   half gallon per minute mist noz-      water soluble, general plant fer-
container plus enough for a small     zle is also handy for watering        tilizer with the three percentages
amount to run out the drainage        seedlings.                            either very close or identical in
hole in the bottom of the pot.            When watering, go through         value. Generally, it is more cost
    The decision of how often to      the greenhouse systematically so      effective to purchase the highest
water should not be based on          that plants are not missed. Apply     analysis available (highest value
habit, nor should watering sim-       water gently so that the soil does    for N-P-K).
ply be done at certain time inter-    not puddle, wash excessively, or           Water soluble fertilizers can
vals. Always check plants to de-      knock-over young seedlings. This      be applied by mixing a mea-
termine if they require water.        may require repeated light appli-     sured amount of fertilizer, ac-
One advantage to a soil contain-      cations, especially to flats. When     cording to the product label,
ing peat moss is that it changes      done, wind the hose close to the      with water in a watering can and
from dark brown when wet to           faucet so it is not under foot and    drenching the potting soil.
light tan in color when dry. This     hang the watering wand and            However, this method can be-
color change can be used to de-       breaker up off the floor to pre-       come a time-consuming task if
termine when to water. Like-          vent the spread of diseases.          you have a large number of
wise, soil containing peat moss       Hoses last longer if the water is     plants. A simple fertilizer injector
changes from heavy when wet           turned off at the faucet and the      that delivers fertilizer into the
to much lighter in weight when        hose is drained after use.            water line can be purchased
dry. With practice and experi-                                              from garden centers and mass
ence, lifting pots periodically can   Fertilizer                            market outlets. Common brands
help you determine when it is                                               are Siphon, Siphonex, and
                                           Fertilizer requirements for
time to water. This method is es-                                           Hozon. These units attach be-
                                      plant growth can be classified
pecially useful for hanging bas-                                            tween the faucet and hose and
                                      into two groups according to the
kets. Sticking your finger into                                              have a siphon tube that is placed
                                      amount used by plants. The
the soil about a half-inch to feel                                          in a bucket filled with concen-
                                      macronutrients nitrogen, phos-
for moisture can also be used.                                              trated fertilizer solution. The
                                      phorus, potassium, calcium, mag-
Many plants develop a gray-                                                 concentrated solution is drawn
                                      nesium and sulfur are needed in
green cast to the foliage when                                              into the hose, diluted in water,
                                      relatively large quantities while
dry. This can be used to judge                                              and delivered to plants during
                                      the micronutrients iron, man-
when to water. The goal, how-                                               the normal watering operation.
                                      ganese, boron, zinc, molybde-
ever, is to water before plants                                             Follow the manufacturer’s direc-
                                      num, copper, and chlorine are
wilt. Wilting damages plants,                                               tions for mixing the concentrated
                                      needed in very small amounts.
often causing lower leaf loss,                                              fertilizer solution.
                                      Calcium, magnesium, and sulfur
stunted growth and delayed                                                       How often to apply liquid
                                      are generally supplied by adding
flowering.                                                                   fertilizer depends on the growing
                                      dolomitic limestone and super-
    Hand watering is probably         phosphate to the potting soil at      environment, the plant type, and
the most common watering              the time of mixing. Adding mi-        how rapidly the plant is growing.
method used in hobby green-           cronutrients at the time of mixing    Plants in high light and tempera-
houses. Hand watering should          supplies plant needs for these nu-    ture during late spring, summer,
be done early in the morning so       trients for three to four months.     and early fall can be fertilized
that water on the foliage dries                                             about once a week, especially
                                           The macronutrients nitrogen,
before nightfall. A watering can                                            annual flowers, flowering potted
                                      phosphorus, and potassium are
with a water breaker fitting is                                              plants, and vegetables. Medium
                                      highly soluble and wash from
useful for watering dry spots or                                            growth rate plants and plants in
                                      the potting soil easily. Therefore,
an occasional water-hungry                                                  moderate light and temperature
                                      they must be applied frequently,
plant but for larger jobs, a hose                                           during early spring and late fall
                                      often in liquid form. There is a
will be needed. The hose usually                                            can be fertilized about once
                                      wide range of water soluble fer-
has a thumb valve to control                                                every two weeks. Slow growing
                                      tilizers available in garden cen-
water flow, a water wand to ex-                                              plants and plants under shade
                                      ters and mass market outlets, but
tend reach (usually a 2-foot                                                can be fertilized about once a
                                      all will provide the percentage
wand is sufficient) and a water                                              month. Many plants that stop
                                      of nitrogen, phosphorus, and
breaker nozzle (21⁄ 4-inch diame-                                           growing in the winter should not
                                      potassium (example: 20-20-20 is
ter has wide application) at the      percent N-percent P-percent K)

                                                                   Hobby Greenhouse Operations and Practices   5
be fertilized until growth resumes         Seed should be sown in          ture of 70 to 80 degrees F works
in the spring.                        moist, but not wet seedling mix.     well for many seeds. Check the
                                      In the process of sowing, do not     seed package for temperature
Propagation                           place seed too close together or     information. Soil temperature can
                                      competition for space will result    be monitored with a soil ther-
     Every hobby greenhouse
                                      in spindly, weak seedlings.          mometer, which you can pur-
owner either already has an inter-
                                      Resist the temptation to sow         chase from greenhouse supply
est in propagating plants or will
                                      more seed than you really need.      company. Placing sown contain-
soon develop one; there is some-
                                      Follow the directions on the         ers on an electric germinating
thing fascinating about becoming
                                      seed package for seed spacing        mat (soil warming mat designed
involved in starting a new life.
                                      and sowing depth. Large seed         for propagation) that can be pur-
Besides always purchasing estab-
                                      are placed in holes dibbled in       chased from greenhouse supply
lished plants to meet your needs
                                      the soil—a good rule is to make      companies can accelerate seed
can be expensive.
                                      the hole no deeper than twice        germination. Remove the tents as
                                      the diameter of the seed. Small      soon as the majority of the
Seed Germination                      seed are often sown directly on      seedling unfold cotyledon leaves
     Start with good quality, fresh   the soil surface and covered by      and place them at growing light
seed of known parentage. Seed         sifting a small amount of fine        intensity. Seedlings should be
collected from the wild or from       vermiculite (fine or super fine        transplanted to larger containers
the neighbor’s yard often does        grade) or seedling mix over the      before they begin to crowd, es-
not produce plants like the origi-    seed. A good way to water sown       pecially those sown in open flats.
nal. For flowering annuals and         containers without washing the       Seedlings with one or two mature
vegetables, purchase named vari-      seed out of place is to submerge     leaves survive transplanting better
eties from reputable sources. Mail    the container in a shallow pan of    than older seedlings, so do not
order sources and reputable gar-      water so moisture can be ab-         delay transplanting!
den centers are the best sources      sorbed by the soil through the
because they often carry the best     drainage holes. Be sure to label     Rooting Cuttings
varieties adapted to your area        the containers to identify what
and they turn over their invento-     was sown. Store leftover seed             Growing plants from cuttings
ries fast enough so the seed are      sealed in labeled zip-lock plastic   involves removing a plant part
not too old. Stay away from bar-      bags placed in the vegetable         and placing it under conditions
gain basement seed sales.             keeper of a refrigerator for fu-     that favor development of a new
     There are many different         ture use. Note any instruction on    root system. This is a form of
types of containers for germinat-     the seed package for how long        cloning, often called vegetative
ing seed. They include plastic        seed will remain viable under        propagation, because the new
pots, paper pots, peat pots, peat     storage conditions.                  plant will be genetically identical
blocks, multi-cell trays, and open                                         to the parent plant. Vegetative
                                           Seed require a warm, moist
flats. The container to choose de-                                          propagation is often less expen-
                                      environment to germinate.
pends on seed size. Large seed                                             sive and faster than starting
                                      Tenting is an easy way to pro-
probably perform best sown indi-                                           plants from seed.
                                      vide high humidity during ger-
vidually in pots; medium and          mination and to prevent seed              Many plants are easy to root
small seed perform best sown in       from drying out. On a small          from cuttings. Some can be root-
multi-cell trays; and very small      scale, slip the sown containers in   ed directly in a glass of water
seed perform best sown in rows        a plastic bag (large zip-lock bags   placed in a bright window that
in open flats. Seedlings in open       work well) and seal the open         does not get direct sun. In gener-
flats will require transplanting       end. On a larger scale, construct    al, herbaceous annuals and
soon after germination. The con-      a tent over a greenhouse bench       perennials and tropical foliage
tainers should be filled with a        from plastic pipe and clear sheet    plants are easier to root than
potting soil designed for seed        plastic. Do not expose the tents     woody trees and shrubs. Select a
germination. Generally, seedling      to direct sunlight. A piece of 40    healthy disease- and insect-free
mixes are finer textured than          to 60 percent shade fabric or        parent plant, preferably one that
general potting soils so they can     cheesecloth can be used to           does not have flowers. With a
accommodate small seed.               shade the tents.                     sharp knife, remove a 3- to 5-
Seedling mixes can be purchased                                            inch cutting from a stem tip of
                                           Germination temperatures
from garden centers and mass                                               the parent plant. This type of cut-
                                      vary greatly depending on the
market outlets.                                                            ting is called a terminal cutting. If
                                      plant species, but a soil tempera-
                                                                           the cutting has flowers or flower

6 Alabama Cooperative Extension System
buds, remove them. Trim the            nation. Cuttings may require              tions of the science of how to
larger leaves from the lower end       from 2 weeks to 6 months to               grow plants. However, the artis-
of the cutting so that three to four   root depending on the species             tic side of a hobby greenhouse
smaller leaves remain toward the       and plant type, so be patient.            is to choose plants that look and
cutting tip. Dip the cut end of the         Another method for rooting           grow well and that please the
cutting into a rooting powder          cuttings that is used by serious          owner. Choose a reasonable va-
(purchase from garden center or        hobby greenhouse owners, espe-            riety of plants and then arrange
greenhouse supple company)             cially for cuttings of woody shrubs       the plants and the interior space
and tap off the surplus. Rooting       and trees, is intermittent mist           in a way that is pleasing, com-
powders come in different for-         propagation (Figure 1). During            fortable, and functional for all
mulations for different types of       propagation, a film of water is            who visit.
plants so select a formulation         maintained on the leaves by ap-
based on the plant type being          plying a fine mist from mist noz-          Additional Reading
propagated. Removing portions          zles attached to a plastic water               American Horticultural Society.
of the stem below the shoot tip        line installed above the bench. A         1982. Gardening under Glass and
of the parent plant can also make      day/nighttime clock turns the sys-        Lights. The Franklin Library/Ortho
subterminal cuttings. However,         tem on early in the morning and           Books, Franklin Center, Pennsylvania.
cuttings taken from too low on         off late in the evening. A cyclic              D.G. Hessayon. 1997. The
the stem may be too woody and          timer activates an electric solenoid      Greenhouse Expert. Sterling Publishing
root slowly, if at all.                valve in the water line to turn the       Company, New York, New York.
     Cuttings can be started in any    mist on for a preset time, typically           Shane Smith. 1992. Greenhouse
of the containers discussed for        five seconds, and then off for a           Gardener’s Companion: Growing Food
seed germination. Generally, a         preset time, typically 5 to 10 min-       & Flowers in Your Greenhouse or
coarse, well-drained potting soil      utes. The key to successful rooting       Sunspace. Fulcrum Publishing, Golden,
such as the 50 percent peat moss       is to set the off time so the leaves      Colorado.
and 50 percent perlite mix out-        are constantly wet without excess              Ian G. Walls. 1996. The Complete
lined in Table 1 promotes rapid        water soaking the soil. Therefore,        Book of the Greenhouse. Sterling
rooting. Poke a hole in the soil       the off-time interval must be ad-         Publishing Company, New York,
and insert the cut end of the cut-     justed for changing conditions, a         New York.
ting into the soil up to the lowest    longer time during cloudy weath-
leaves. Do not stick the cuttings      er or a shorter time during sunny
all the way to the bottom of the       weather.
container. Stick them just deep             Greenhouse growing, like
enough to stand up. Water the          gardening, is both an art and a
cutting immediately. During this       science. Many of the ideas pre-
process, do not allow the cuttings     sented here are practice applica-
to wilt. If cuttings must be trans-
ported or sticking the cuttings
must be delayed, seal them in a          Day-Night     Cyclic Timer     Mist Nozzles
plastic bag with wet paper tow-          Timer
els, place them in a cooler or re-
frigerator and protect them from         Electric           Solenoid
high light.                              Power              Valve
     Because cuttings do not ini-
                                       Gate Valve
tially have roots, they must have
a high humidity environment to
prevent desiccation until roots                 Strainer
                                       21⁄ 2-3’
form. If a few cuttings are stuck      Water Thermostat
in a pot, cover the pot with a         Supply
clear plastic bag, seal the bag
with a rubber band and place
the pot in bright, but not direct
light. On a larger scale, construct
a tent over the cutting containers
on a greenhouse bench from
plastic pipe and clear sheet plas-     Figure 1. Design for an intermittent mist propagation system
tic as discussed for seed germi-

                                                                       Hobby Greenhouse Operations and Practices      7
           J.R. Kessler, Jr., Extension Horticulturist, Assistant Professor, Horticulture,
           Auburn University

           For more information, call your county Extension office. Look in your tele-
           phone directory under your county’s name to find the number.
           Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June
           30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama
           Cooperative Extension System (Alabama A&M University and Auburn University) offers educational programs,
           materials, and equal opportunity employment to all people without regard to race, color, national origin, religion,
ANR-1153   sex, age, veteran status, or disability.                               UPS, 5M16, New July 1999, ANR-1153

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