Asparagus is has been grown for at least two millennia. It is not susceptible
to many disease problems. It's a good source of vitamin A and also has
good amounts of calcium, folic acid and Vitamin C. A cool season perennial
which can live for decades, asparagus does require some work to get
started, but unlike other vegetables, it will keep producing for many
many years. It will need regular watering in early years but requires
much less work than most other vegetables once it becomes established.
Besides, those little shoots peeping out each year are a great harbinger
that spring has arrived... plus, once you've tasted freshly-picked asparagus,
you'll never go back to the store-bought stuff!
Asparagus has a large root system with feeder roots and rhizomes that
develop into spears and storage roots. Roots can grow very deep (at
least 6') and wide. Warning: asparagus will not tolerate wet feet—if
you have an area with a high water table, do not plant them there. Asparagus
prefers a soil pH of 6.5-7.5, and doesn't do well if pH is less than
6.0.
Each planting row should be a furrow at least 5-6 inches deep and as
wide; keep rows about 5 feet apart. Loosen soil as deeply as you can
from the bottom of the furrow. If the soil removed from the furrow was
a sandy loam, it can be mounded for filling in as the plants grow. If
you have a fine clay or silt soil, remove it and use it in a low spot
elsewhere (or use a raised bed). Mix several inches of a good planting
mix and some in the bottom of the furrow. If lime is needed to adjust
soil pH, add that at this time.
Next, make a small mound so the asparagus crown will be on top and
the roots spread around it. Plant the crowns/roots 4-6 inches deep (shallower
in clay soils). Cover them 3 inches with half organic and half sandy
loam mix (or use a good planting mix if you have clay soil), then wet
the entire row. When the plants are several inches tall, add another
layer of the above mix (avoid covering the foliage - it's better to
fill too slowly than too quickly) until the furrow is full. Water weekly
if it doesn't rain. (Stop watering in early autumn to encourage dormancy.)
Pick no asparagus shoots the first year to allow the foliage to grow,
yellow and die on its own. This creates the food for the roots. Mulch
in autumn with straw, compost or straw-y manure to reduce heaving from
freeze-thaw cycles and to delay early spring emergence of spears. During
early spring of each year, remove the dead foliage and any overwintering
weeds. (Don't cut the fern down in the fall—the dead fern will
catch moisture and snow in the winter and will keep the soil temperature
about 5 degrees colder than the temperature of bare soil. This colder
soil temperature will delay early emergence of spears in the spring,
which could then be killed by a spring frost.) Also broadcast lime,
if it is needed to maintain the proper soil pH. At the same time spread
2 to 3 pounds of 5-10-10 fertilizer per 100 square feet and rake both
fertilizer and lime into the upper 1-2 inches of soil.
The second year, pick sparingly only those stalks as big as your finger.
Keep watering, fertilizing, and mulching with manure and compost.
The third year is the year to really begin harvesting. The 2-4-8 week
sequence is a good rule: pick for two weeks the third year, four weeks
the fourth year, and eight weeks from then on. To harvest—when
the stalks are at least 7 inches high, just snap where they begin to
be tender and enjoy. (If you use a knife or clippers, you risk accidentally
cutting immature spears and also spreading disease between plants.)
Stop harvesting when a majority of the shoots are smaller in diameter
than a pencil.
Good companion plants for asparagus are tomato, parsley, and basil.
By the way, just a bit of trivia—asparagus is one of a fairly
small number of salt-tolerant vegetables—it used to be traditional
to sow salt on asparagus beds to control weeds. (We wouldn't recommend
that in most places—the salt might run off and kill less tolerant
plants.)