General Horticulture • HO-91-W
Department of Horticulture
Purdue University Cooperative Extension Service • West Lafayette, IN
Spring Garden Calendar
B. Rosie Lerner and Michael N. Dana
Timing horticultural events and practices can vary from Woody Landscape Plants & Fruit Trees
year to year, depending on weather conditions. The March
following information is intended as a general guide. • Prune trees and shrubs while plants are still dor-
Regional differences are noted when practical. Adjust mant. Those that bloom early in spring should be
activities according to local weather and site conditions, pruned after flowers fade.
and be sure to read label directions thoroughly on all • Fertilize woody plants before new growth begins, but
products. wait until after soil temperatures have reached 40°F
(usually in early March in Southern Indiana, and late
Indoor Plants & Activities March to early April in Northern Indiana). Two
March pounds of actual nitrogen per 1000 square feet
• Apply fertilizer to houseplants according to label should be broadcast over the entire root area.
directions as days grow brighter and longer and new • Remove winter coverings from roses as soon as
growth begins. Foliage plants require a relatively new growth begins, but keep mulch nearby for
high-nitrogen fertilizer, while blooming plants thrive protection from late freezes. Prune and fertilize as
on formulations that are higher in phosphorus. needed.
• Remove spent leaves and flowers regularly to • Apply superior oil spray to control scale insects and
improve appearance and encourage more blooms. mites on landscape plants and fruit trees when tips
• Start seeds of cool season plants for transplanting of leaves start to protrude from buds.
outdoors later in spring (early March for Northern • Remove tree wrap from trunks to prevent scalding
Indiana, late February for Southern Indiana). due to overheating of bark.
• Pot-up roots of tuberous begonias and caladiums in • Plant a tree in celebration of Arbor Day, the last
April for transplanting to the garden later. Friday in April in Indiana.
• Prune, repot, and clean houseplants as needed. • Bare-root stock should be planted before new top
• Start seeds of warm-season crops for transplanting growth begins. Balled-and-burlaped and container
later to the garden (early April for Northern Indiana, stock can still be planted later in spring.
late March for Southern Indiana). • Remove and destroy overwintering bagworms from
• Keep Easter lilies in a bright, cool location out of landscape trees and shrubs.
direct sunlight. Water as soil begins to dry. The • Follow home orchard spray schedule to control
yellow pollen-bearing anthers inside the flower can insects and diseases. While trees are in bloom, use
be removed to prevent staining of the petals. a pesticide containing fungicide only and no insecti-
May cide and thereby avoid injury to bees. Read and
• Many indoor plants can be moved to a shady follow all label directions.
location outdoors after danger of frost is past (May). May
Plants will dry out more when kept outdoors, so • Thin fruits of apple (and other fruit trees if needed)
check soil moisture often. Sinking the pots in the about 3 weeks after petal fall. Apples should be
ground will help slow down moisture loss, but spaced on the average of about 8 inches apart;
regular watering will still be necessary. peaches at 6 inches apart. If a large crop is set and
• Use cuttings of houseplants to increase your collec- no thinning is practiced, all fruit will be small and
tion or share with your friends. Root the cuttings in branches may break.
media such as vermiculite, perlite, or potting soil • Apply fungicide sprays to roses to control diseases
rather than water. Roots grown in water tend to be such as black spot.
weak from lack of oxygen and do not adjust well to • Prune early spring flowering trees and shrubs after
being planted in soil. flowers fade.
Reviewed 4/01 Purdue University Cooperative Extension Service Page 1 of 2
General Horticulture • HO-91-W
Lawn • Plant sections of certified, disease-free potato “seed”
• Rake to remove leaves, twigs, and trash. • Remove winter mulch from strawberry beds as soon
• Mow lawn as needed. The first mowing should be as new growth begins, but keep the mulch nearby to
slightly lower than normal to encourage green-up. protect against frost and freezes and to help keep
April weeds under control.
• Seed bare spots. • Remove weak, diseased, or damaged canes from
• Apply pre-emergence herbicides to control crabgrass raspberry plants before new growth begins. Remove
(April 1-20 Southern Indiana, April 21-May 10 North- old fruiting canes (if not removed last year), and
ern Indiana). The herbicide siduron is the only shorten remaining canes if necessary.
crabgrass preventer that can be used on newly • Prune grape vines to remove dead or weakened
seeded lawns. limbs, and repair support trellises as needed.
May • Celebrate National Gardening Week in April. Dates
• If needed, apply billbug control to prevent egg laying vary each year; check with your local county office of
or damage from larvae feeding. the Purdue University Cooperative Extension Service
• Apply post-emergence herbicides to control for exact dates.
broadleaves if they are a problem. Be careful to avoid May
spraying or drifting herbicide onto garden plants. • Allow foliage of spring flowering bulbs to remain in
• Fertilize in May using a 4-1-2 ratio of nitrogen, place after blooms fade. Leaves manufacture the
phosphorus, and potassium at the rate of 1 pound of food reserves, which are then stored in the bulb for a
actual nitrogen per 1000 square feet. repeat showing next year.
• If needed, apply insecticides to control sod webworm. • Plant frost-tender plants after danger of frost is past
• Begin now to search for sod webworm or other turf- for your area (mid May in Northern Indiana, late April-
feeding caterpillars. Apply chemical controls only if a early May in Southern Indiana.
large number of caterpillars are present. • Pinch chrysanthemums and annual flower plants to
keep them compact and well-branched.
Flowers, Vegetables, & Small Fruit • Make successive plantings of beans and sweet corn
March to extend the season of harvest.
• Prepare garden soil for planting. Do NOT work the • Thin seedlings of earlier planted crops such as
soil while it is wet. Soil should crumble when carrots, lettuce, spinach, and beets to their proper
squeezed in your hand when it is ready to work. If spacing.
soil forms a solid ball when squeezed in your hand, • Harvest early plantings of radishes, spinach, and
it’s still too wet. lettuce.
• Follow last fall’s soil test recommendations for • Harvest asparagus by cutting or snapping spears at,
fertilizer and pH adjustment. (It’s not too late to soil or just below, the soil level.
test if you missed last year.) • Harvest rhubarb by cutting or by grasping the stalk
• Start seeds of warm season vegetables and flowers and pulling up and slightly to one side.
indoors. (In North and Central Indiana, wait until end • To prevent bacterial wilt in cucumbers, control
of March, early April.) cucumber beetles, the carriers of the disease, as
• Watch for blooms of early spring bulbs such as soon as plants germinate or are transplanted.
daffodils, squill, crocus, dwarf iris, and snowdrops. • Remove blossoms from newly set strawberry plants
• Remove old asparagus and rhubarb tops, and then to allow better runner formation.
side dress with nitrogen or manure. • Remove unwanted sucker growth in raspberries
April when new shoots are about a foot tall.
• Plant cool-season vegetables and flowers as soon as
the ground has dried enough to work.
• Harden off transplants before planting outdoors by The authors wish to acknowledge the assistance of Tim
gradually exposing the young plants to outdoor Gibb and Clark Throssell in the preparation of this
conditions of wind, brighter sunlight, and lower manuscript.
• Plant or transplant asparagus, rhubarb, and small
fruit plants such as strawberries and brambles. For more information on the subject discussed in this
Divide rhubarb and replant, if last year’s planting publication, consult your local office of the Purdue
produced seedstalks. University Cooperative Extension Service.
It is the policy of the Purdue University Cooperative Extension Service, David C. Petritz, Director, that all persons shall have equal opportunity and access to programs and facilities
without regard to race, color, sex, religion, national origin, age, marital status, parental status, sexual orientation, or disability. Purdue University is an Affirmative Action employer.
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