Tuesday, July 6, 2010

Growing Asparagus

Asparagus grows in most any soil as long as it has good internal drainage. Asparagus roots do not like waterlogged soils that will lead to root rot. Till to a 6 inch depth before planting.

Buy one-year-old, healthy, disease-free crowns from a reputable crown grower. A crown is the root system of a one-year-old asparagus plant that is grown from seed. Each crown can produce 1/2 lb. of spears per year when fully established.

Asparagus is a long-lived perennial vegetable crop that is enjoyed by many gardeners. It can be productive for 15 or more years if given proper care.

Asparagus can be planted throughout the northeast from mid-April to late May after the soil has warmed up to about 50 degrees F. There is no advantage to planting the crowns in cold, wet soils. They will not grow until the soil warms and there is danger of the plants being more susceptible to Fusarium crown rot if crowns are exposed to cold, wet soils over a prolonged period. Plant the asparagus at either the west or north side of the garden so that it will not shade the other vegetables and will not be injured when the rest of the garden is tilled.

Dig a furrow no deeper than 5 to 6 inches. Research has shown that the deeper asparagus crowns are planted, the more the total yield is reduced. Apply about 1 lb. of 0-46-0 (triple superphosphate) or 2 lbs. of 0-20-0 (superphosphate) fertilizer per 50 feet of row in the bottom of the furrow before planting. This will make phosphorus immediately available to the crowns. Omitting this procedure will result in decreased yields and the spear production will not be as vigorous.

Toss the crowns into the furrow on top of the fertilizer. The fertilizer will not burn the crowns, and the plants will grow regardless of how they land so don't bother to spread the roots. Space the crowns 1-1/2 feet apart in the row. If more than one row is planted, space the rows five feet apart from center to center. Wide between-row spacing is necessary because the vigorously growing fern will fill in the space quickly. Wide spacing also promotes rapid drying of the fern to help prevent the onset of fungus diseases.

After planting, back fill the furrow to its original soil level. It isn't necessary to gradually cover the crowns with a few inches of soil until the furrow is filled in. However, do not compact the soil over the newly filled furrow or the emergence of the asparagus will be severely reduced. Spears should emerge within one week in moist soils.

Do not harvest the asparagus during the planting year. Spears will be produced from expanded buds on the crown. As the spears elongate and reach a height of about 8 to 9 inches, the tips will open. The spear will become woody to support the small branch lets that become ferns. The ferns produce food for the plant and then move it down to the crown for next year's spear production.

Asparagus is very drought tolerant and can usually grow without supplemental watering because it seeks moisture deep in the soil. However, if rainfall is insufficient when planting or afterwards, it is beneficial to irrigate the crowns. Otherwise the plants will become stressed and growth will be slowed.

Harvesting

Harvest asparagus by snapping 7 to 9 inch spears with tight tips. There is no need to cut asparagus below the soil with a knife. This may injure other buds on the crown that will send up new spears. The small stub that is left in the soil after snapping dries up and disintegrates. A new spear does not come up at the same spot, but comes up from another bud that enlarges on another part of the crown.

As the tips of the spears start to loosen (known as "ferning out"), fiber begins to develop at the base of the spears, causing them to become tough. The diameter of the spear has no bearing on its toughness. When harvesting, the asparagus patch should be picked clean, never allowing any spears to fern out, as this gives asparagus beetles an excellent site to lay their eggs.

The year after planting, asparagus can be harvested several times throughout a three-week period, depending on air temperatures. Research shows there is no need to wait two years after planting before harvesting. In fact, harvesting the year after planting will stimulate more bud production on the crown and provide greater yields in future years, as compared with waiting two years before harvesting.

Asparagus spears will start to emerge when the soil temperature reaches 50 degrees F. After this, growth of asparagus is dependent on air temperature. Early in the season, 7 to 9 inch spears might be harvested every 2 to 4 days. As air temperatures increase, harvesting frequencies will increase to once or twice per day, harvesting 5 to 7 inch spears before the tips start to fern out and lose quality. The second year after planting, the length of harvest can increase to about 4 to 6 weeks. The third year after planting and thereafter, harvesting can continue for 6 to 8 weeks. Since the length of harvest season will vary from year-to-year depending on air temperature, stop the harvest when the diameter of 3/4 of the spears becomes small (less than 3/8 inches). Experience gained by growing the crop will make it easier for the gardener to know when to discontinue the harvest.

When harvest is finished, snap all the spears off at ground level. Apply 1/2 lb. of ammonium nitrate fertilizer per 50 feet of row. At this time, a home garden formulation of glyph sate non-selective herbicide (such as Roundup) can be sprayed on the asparagus patch. This will kill any existing weeds. New spears will then emerge; fern out, and provide a large canopy to cover the space between the rows. Once a dense fern canopy is formed, weed growth will be shaded out.

Storage

Asparagus is very perishable and should be harvested in the morning when air temperatures are cool. After picking, immerse the spears in ice-cold water to remove the heat; then drain the water and place the spears in plastic bags. Store in the refrigerator at 38 to 40 degrees F. Asparagus will keep for 1 to 2 weeks with little loss of quality.

1 comment:

Anne said...

Roundup?!? Skip the roundup and weed. You don't want that stuff near any crops you consume. Roundup is a Monsanto product.

Yes there are all male hybrid varieties that you can plant and they do have tasty spears. The OP and heirloom strains like Martha Washington and Mary Washington are also excellent choices.

Here's the difference... the asparagus patch that I grew up with and is still going strong on my Mother's farm and is many decades old. They send out flowers, which some bees enjoy, then produce red berries that the birds enjoy. The birds in addition will spread the asparagus seed by means of their droppings (so don't be surprised if it pops up along fence lines). As well the asparagus patch will have to be weeded from volunteers if it gets crowded, or you can do what we do and just share the extra crowns.