Dennis Morgeson Agent for Horticulture Washington
One of the first true signs that spring is here is that first mess of asparagus and it has finally
emerged from its cold winter nap. If you haven’t checked your bed yet do so soon or you might lose
your first picking. If you would like to start a bed of asparagus now is the time to plant!
Asparagus is a long lived perennial vegetable crop. Each plant can be productive for
15 or more years if given proper care. Asparagus will grow in most any soil as long as it has good
drainage. Asparagus doesn’t like to have wet feet, it leads to root rot. An ideal pH of 6.5 to 7.5 will give
you good results; it will not tolerate a pH under 6.0. If you are thinking of planting asparagus have a soil
test done and the soil amended before planting. If you aren’t willing to test your soil apply 10-20-10 or a
similar fertilizer at a rate of 6 pounds per 1000 square feet; this can also be broadcast around
established plants for added growing power.
Only buy one year old, healthy, disease-free crowns from a reputable grower. Asparagus is sold
in crowns which are one year old plants grown from seed. When fully established each crown can
produce ½ pound of asparagus spears. You can start your own asparagus from seed but it will have to
grow one year where you sow it. The following spring it will have to be dug and spaced out in its
permanent location. This basically means you lose one year of spear production in your garden.
Another disadvantage to planting asparagus by seed is getting the variety you want; the best varieties
aren’t usually available in seed form.
When selecting a variety of asparagus there are some interesting things to consider. There are
new varieties on the market which are far superior to the old varieties. New all male hybrid asparagus
such as Jersey Giant, Jersey Prince, and Jersey Knight, these varieties do not produce seed. Basically
when asparagus seeds the new plants become weeds that must be pulled out as to not overcrowd the
bed. Female plants expand a lot of energy making seeds and don’t produce as many edible spears as do
the male plants. The new all male asparagus varieties generally out produce the old Mary Washington
varieties by 3 to 1.
Asparagus should be planted after the soil has warmed up to about 50 degrees, usually in April.
There is no advantage to planting it earlier because it won’t grow until the soil warms and the longer it
sets in cold wet soil the more likely it is to rot. If you plant asparagus in the vegetable garden plant it on
the west or north side so it won’t shade the other vegetables.
When planting asparagus dig a furrow no deeper than 5-6 inches, if you plant it any deeper
overall yield will be reduced. Apply 1 pound of 0-46-0 (triple super phosphate) or 2 pounds 0-20-0
(super phosphate) fertilizer per 50 foot of row in the bottom of the furrow before planting. This will
stimulate root growth and increase later yields. Toss the crowns into the furrow on top of the fertilizer,
it won’t burn the roots, and the plants will grow just fine regardless of how they land in the furrow. The
crowns should be space 1-1/2 feet apart. If you plant more than one row space them five feet apart.
After planting, back fill the furrow to its original level. You don’t have to gradually fill the
furrow, just make sure not to walk on it; this will pack the soil down. If the soil is warm and the
asparagus is kept moist it should emerge in a week or so after planting.
One important thing to remember is NOT to harvest the asparagus the first season. It will need
all of its energy to produce a larger crown and store food for the following season. If we have a dry
summer keep it watered, especially the first year. Generally asparagus doesn’t need to be irrigated,
however if we have an exceptional drought the following years harvest will be reduced if you don’t
There aren’t many insect and disease problems on asparagus. The one real problem is
asparagus beetles which chew on the leaves and stems causing them to turn brown. This can reduce the
yield the following season. Sevin will give good control of asparagus beetles; simply spray at the first
signs of damage.
At the end of the growing season don’t cut down the ferns. Leave them through the winter.
They will help protect the root systems by catching snow and keep the soil moist and cool. By keeping
the soil cool the asparagus will be delayed and won’t be as likely to get frost damaged in the spring.
Around the last of March the old ferns can be mowed as low as possible.
I have always heard of people using salt for weed control in asparagus, but it’s really not
necessary. Salt will actually impede water infiltration into the soil and can leach into surrounding areas
killing other vegetables and plants that aren’t as salt tolerant. The first year use a good layer of mulch
for weed control, and it will also conserve moisture. You can also use labeled pre-emergent herbicides.
If you have an old patch of asparagus you can spray round up over the bed before the fronds emerge.
This will kill any existing weeds; this is a good time to apply a layer of mulch. It’s a good idea to apply ½
pound of ammonium nitrate fertilizer per 50 feet of row each year when harvest is finished. This will
increase shoot growth, which will increase food storage, which will increase harvest the following
Once you start harvesting asparagus it can continue until 75% of the new spears emerging from
the soil are less than 3/8 of an inch wide. At this point you should discontinue harvest. Asparagus
should be harvested in the morning while it is freshest and stored in the refrigerator at 38-40 degrees. If
you have any questions call me at the office at 859-336-7741. Happy Gardening.