Asparagus
In The Home Garden
by John W.
Weeks
Asparagus is a
perennial vegetable native to Western Europe on limestone soils.
Asparagus is a member of the lily family and the Asparagus family
includes many species prized for their ornamental values. "Asparagus
asparagoides (medeoloides), commonly known as
Smilax, has long twining shoots furnished with small, broad,
shiny leaves; it was formally in great demand for floral
decorations, but is less used today." Asparagus
verticillatus grows about 10 feet high and bears an
abundance of red berries. It is an excellent plant for draping a
pillar in the greenhouse. Asparagus fern, Asparagus plumosus and
its varieties are tender perennial plants with underground fleshy
roots, erect or climbing stems, and tiny spiny branches bearing
inconspicuous flowers which are followed by round, reddish
berries containing small black seeds. They are grown out doors in
frostless or near frostless regions, elsewhere in greenhouses and
as house plants. They prefer rather shady moist conditions, and
should be grown in a compost of loam and leaf mold with a
scattering of sand. The minimum winter temperature of the
greenhouse should be 50 degrees. The ornamental kinds of
Asparagus are grown for the value of their graceful leafy shoots,
which are admirable for cutting for decorative purposes. Most of
the greenhouse kinds are natives of South Africa. Although they
are moisture loving plants and require an abundance of water
during the summer, they must be rested during the winter by
allowing the soil to become almost dry before it is watered: they
are liable to lose their leaves in winter if overwatered. Well
rooted plants derive great benefit from biweekly waterings with
dilute fertilizer during the summer."
The common edible
asparagus will last at least 20 years in the garden. It's crucial
to properly prepare the site prior to planting so that there will
be a good depth of rich, fertile, well-drained soil. Asparagus
prefers rich sandy well drained loam soils. In the case of clay
soils the ground should be excavated to a depth of 2 feet, and
drainage should be encouraged by putting in stone, broken brick,
or modern perforated plastic tile along with the addition of
organic matter in the subsoil. Spade manure, leaf mold, rotted
leaves or peat into the bottom of the trench. The soil that has
been dug from the trench should now be prepared by spading
organic matter into it along with at least 4 ounces or more of
bone meal per square yard. In Western Washington and Oregon, with
the regions acid soils, we also recommend adding lime at a rate
of about one pound of dolomite lime into each 10 feet of trench.
Bone meal works like lime and also contains phosphorus. If lime
is used rather than bone meal, it is important to add phosphorus.
Use a 0-20-0, or even a 0-40-0, spreading in liberally in the
bottom of the trench or furrow.
Before proceeding,
it is important to point out that the organic clay asparagus bed
should be prepared in the Fall of the year. The asparagus
roots should be planted in the spring (late February through
early April). This allows the organic matter to compost
thoroughly prior to planting the asparagus roots, and this
foresight and patience on the part of the gardener can spell the
difference between success and failure. Asparagus roots are soft
and starchy, rather than woody, and can easily compost if planted
with rotting manure, etc.
Spring planting is
recommended for asparagus roots. In clay soils that have been
properly prepared last Fall, plant the crowns at soil level or
just 1 to 2 inches below and cover with 2" of soil. In the
fall, cover with 2 more inches of soil. Asparagus crowns migrate
to the surface of the soil over time because the new crown grows
on top of last year's crown every year. Asparagus beds should be
maintained so 3 to 5 inches of soil covers the crowns. Crowns
that are cultured too shallow yield spindly spears. Crowns that
are cultured too deep tend to grow to the surface more rapidly,
and yield of the early crops are adversely affected. For maximum
yield it is important to properly orient the crowns when planting
with the crown on top and the roots or "legs" spread in
a downward direction. This is most easily achieved by forming a
ridge of soil placed in the center of the trench, or individual
pyramids of soil placed in the center of the trench so the crowns
can be properly "perched" on the ridge or pyramids
prior to covering with soil. Never allow two plants to touch in
the planting trench. A spacing of 15 to 18 inches is about right.
The above planting
instructions are especially recommended for growers in Western
Oregon and Washington State, where clay, acid soils are quite
common. If one is blessed with a sandy loam--well drained soil,
then only lime, phosphorus and bone meal amendments are crucial
to success. The addition of organic matter is always helpful, but
not mandatory. Again, if incorporating organic matter, be sure
and do so far enough ahead of time so composting does not occur
at the time of planting.
On well drained
sandy--loam soils far less bed preparation is mandatory. Trenches
12 inches wide, 8 inches deep and 4 to 6 feet apart work nicely.
We recommend planting and maintaining the same depth in the
discussion of clay soils.
Once established,
asparagus is easy to care for. Asparagus is extremely deep rooted
and therefore water and nutrients are not as critical as is the
case with a lot of crops. At our nursery we have grown test plots
of asparagus with no irrigation or fertilizing several years in a
row. Our theory has been the asparagus roots lay deep enough to
pick up moisture and nutrients on their own. We do water and
fertilize nearby crops and in the home garden this is normally
the case as well. Oregon State University Extension Service wrote
a flier based on information gleaned from "Growing Asparagus
in the Garden" by Harwood Hall, Susan Wadea, Ronald Voss, a
University of Cal. publication, leaflet 2754 and "Commercial
Growing of Asparagus" U.S. Dept. of Agriculture Farmer's
Bulletin No. 2232. The OSU Ext. flier writes "Fertilize
annually when harvest has been completed and the plants begin to
fern out. Apply manure and 8 to 10 pounds of a complete
fertilizer (5-10-10 or 1-10-5) per 100 feet of row. Most
irrigation should be done during the "fern season," not
the harvest season. Control weeds by hoeing; avoid wounding the
plant or the soon to emerge spears."
Insects: "The
asparagus beetle and the spotted asparagus beetle can cause
widespread damage. The adult asparagus beetle is 1/4 inch long,
metallic blueblack with orange to yellow markings. It feeds on
spears. The adult and it's gray larvae feed on the berries. The
spotted asparagus beetle is brick red with black spots. It feeds
on both spears and ferns. It's larvae feed on the berries."
In Western Oregon and Washington the 12 spot bean beetle also
feeds on the fern during the larval stage. The bean beetle looks
much like a ladybug beetle, only the bean beetle is yellow with
black spots. Damage often begins in May. The Pacific Northwest
Insect Control Handbook (1998) notes under the section on Home
Garden Vegetable, Small Fruit, Tree Fruit and Nut Pest that
carbonyl (Sevin)EC and malathion EC are cleared for use on the
Asparagus beetles. Insecticide soaps and other remedies may be
found in the full service garden center. One should check with
your local garden center and carefully follow all directions and
related information on the container, prior to using any
insecticide or other plant "medicine."
Don't harvest
spears the first year. The second season you can harvest for two
or three weeks or until the spears develop ferny stalks. This
practice encourages the roots to store food for the next year's
growth. In the fall when the top (fern) growth browns, cut off
all fern growth at the ground level and dispose of it. Harvesting
the 3rd year and there after can last from 8 to 12 weeks.
Commercial growers cut asparagus 1 to 2 inches below ground level
and at least 2 inches above the crown. A specially manufactured
asparagus knife is helpful in cutting properly. This knife
resembles a large "dandelion digger," which also serve
as a suitable harvesting tool. For our own use we don't bother
cutting below the ground level. We just snap the spear off near
the ground. If the spear bends, rather that snaps, it will be
tough and can best be used by peeling the outer layer or
epidermis off the tough portion of the spear. Europeans use
special asparagus racks to cook peeled spears, so they don't fall
apart in boiling water. We prefer to just snap off spears knowing
if they "snap" they will be tender and require no
peeling. We like to pick a large batch of spears and steam them
in a steamer cooker. After 2 to 3 minutes the asparagus is
"blanched" and a portion can be taken out of the
steamer and frozen for later use. Asparagus is normally fully
cooked in 12 to 18 minutes in a steamer. Picking asparagus in the
late part of the day yields more tender spears than picking in
the morning. Asparagus grows fast during the warm hours of the
day, it tends to be really tender in the evening!
In regard to
nutritional value, USDA leaflet 2754 notes "A 1/2 cup
serving of asparagus spears contains only about 18 calories, and
about 1/4 of the adult daily recommendation (RDA) for vitamin C.
Asparagus is also a significant source of vitamin A, iron and
other essential trace nutrients. White asparagus (which has been
bleached by mounding dirt around the growing spear) contains only
about 1/10 of the vitamin A value of the green type." As an
aside, another way to produce white asparagus is to cut a 55
gallon drum in half lengthwise, or use a plastic drum cut in
half, and lay this over the top of the asparagus bed so it
creates a "shed" or "garage" effect. This
keeps light from striking the spears as they emerge and one only
has to lift the end of the drum to discover the white spears
beneath it.
If you have read
this far, you should be equipped to successfully grow asparagus
in your garden...ENJOY!
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- Mary Washington
- The standard commercial strain and the most popular U.S. variety is resistant to some rust and blight, has a 60 day cutting season. Produces long straight spears with tight tips.
| ![Jersey Knight Asparagus.](img/jersey.jpg)
| - Jersey Knight and Jersey Giant
- Male hybrids with fewer female seed plants than are found in open pollinated varieties. These varieties are high yielding, have excellent fusarium tolerance and high resistance to rust. They have a large attractive spear. Due to greater disease resistance and less expenditure of photosynthate forming seed, live longer than male - female varieties.
- Sweet Purple
This new type of asparagus has many similar characteristics to green asparagus but offers something new for the asparagus connoisseur. The spears produced have several qualities which make it quite different from common green asparagus. 1. The deep-burgundy coloration produced in these spears is the most striking difference between the purple and green varieties. 2. This type has a 20% higher sugar content. Because of this extra sweetness, this vegetable is often eaten raw. Some upscale restaurants garnish salads with purple asparagus. When cooked, the sweetness gives this asparagus a mild, nutty flavor. 3. The spears are generally larger and much more tender than its green counterpart. The vascular bundles have less lignin per spear which make the spears less stringy. This allows the cook to use the entire spear with little waste. |
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