1. Q. I have just purchased some asparagus plants. How should I plant them?
A. Prepare a planting bed by digging out unsuitable soil and replacing it with an organic mixture of 1/3 sand, 1/3 soil, and 1/3 sphagnum moss, compost or potting soil. Plant the asparagus 18 to 24 inches apart in a trench with the crown (buds) 6 inches below the ground level, but with only a thin layer of earth over them. As the growing season progresses, gradually fill in the trench.
2. Q. When should asparagus plantings be divided?
A. Divide asparagus roots during the winter after the tops have been removed. The tops will freeze in North Texas, but in many areas of South Texas they will have to be cut back to produce a crop next year. During this time the roots can be divided easily into individual plants for replanting.
3. Q. How long after planting asparagus can I harvest the first spears?
A. If you plant seed, you should wait 3 years before the first harvest. If you start from 1-year-old crowns (the recommended manner), harvest can begin to a limited degree the next year. Harvesting early will drastically reduce yield as well as quality of home-grown asparagus.
4. Q. How long can I harvest asparagus in the spring?
A. Most home gardeners in Texas harvest asparagus too long in the spring. Length of harvest will depend a great deal on location within the state, but generally the harvest should extend 4 to 6 weeks from the first harvest in early spring. Complete harvest in early spring followed by selective harvest allowing a few spears to develop into ferns is recommended.
5. Q. When I finish harvesting asparagus spears, how should I care for them during the rest of the year?
A. Allow the spears to fully develop into ferns. An occasional selective trimming or pruning can reduce the amount of top growth. Occasional light fertilizing and adequate moisture will help the plant develop sufficient top growth for good spear production.
6. Q. Each year my asparagus produces fairly well, but many of the spears are bent and crooked. What causes this?
A. Asparagus spears grow extremely fast and are highly sensitive to mechanical injury from cultivation, insect feeding or wind- blown soil particles. Spears injured from any cause will grow slowly. Rapid growth on the opposite side of the spears causes them to curve and bend toward the injured side.
7. Q. Can table salt be used for weed control in my asparagus bed?
A. Yes, in limited amounts. Asparagus is more salt tolerant than most vegetable plants, so salt may be used around the growing plants for weed control. However, excessive amounts of salt used in any one season, or salt accumulation over the years, can harm asparagus plants and subsequently reduce spear production. An application of glyphosate herbicides such as Roundup and Ortho Kleanup after the final harvest and when ferns are less than 6 inches tall will control bermuda grass and weeds. Follow label instructions. Certain pre-emergence herbicides can also be used at this time to prevent weed seed sprouting during the growing season.
8. Q. What causes my asparagus spears to get smaller and smaller each year?
A. This condition occurs in the warmer areas of the state, primarily in South Central and South Texas. Spear production is primarily the result of food accumulated in the root system the previous year. If this amount of stored material is decreased because of high temperatures, especially in the fall, or poor growing conditions, spears will be smaller the following spring. These conditions over a long period will gradually result in smaller and smaller spears each year.
9. Q. I have asparagus plants which have grown four feet tall this year. How should I culture them this year and when can I harvest? Also, some plants have red berries and some don't. Why?
A. Please read 'Home and Garden' for all you wanted to know about asparagus (but were afraid to ask). As for the red berries, my readers always have to drag sex into the otherwise respectable subject of horticulture. Asparagus is unusual, among our garden plants, in its flowering habit. While nearly all of our vegetables bear both stamens and pistils (containing pollen cells and egg cells, respectively) on the same plant or in the same flower, asparagus has two kinds of plants. About half bear only staminate (male) flowers; the others bear only pistillate (female) flowers from which the little red seed-bearing fruits develop. Both kinds must be grown near each other if seeds are to be obtained.
10. Q. I know it is recommended to cut the tops of asparagus in late November to force dormancy before sprouting and harvesting begins in early spring. Cold in some areas is not sufficient to kill the tops and cutting is to physically force dormancy but this year the tops of my asparagus plants died before any cold weather occurred. When I removed the dead tops, they appeared to have rotted off at ground level. What happened? Is my asparagus planting dead?
A. Plant pathologists at Texas A&M have diagnosed rhizoctonia fungus as the culprit. Wet conditions allowed the fungus to weaken plants at the soil line causing a rotted appearance. Tops died and now have a blacken appearance. Hopefully, the fungus just affected asparagus at the soil line and did not enter the below ground crowns. If this was the case, asparagus production should resume as normal next spring. Don't feel bad; almost everyone experienced the same condition. Asparagus beds with a heavy, poorly drained soil type were especially susceptible.
11. Q. My family always looks forward to the first harvest of asparagus from the garden. Asparagus is usually the first fresh growth of the garden every spring BUT the first spears (sprouts) we harvest are always tough. What causes toughness in asparagus and how can it be prevented?
A. Toughness of asparagus is due to the development of fiber cells with thick walls containing a material called lignin. These thick-walled cells or fiber cells are located in two different tissues in different areas of the asparagus spear. Some fiber cells are found in the vascular bundles which are scattered throughout the spear with more fibers found near the base than the tip. Therefore, fiber content is very low at the tip of asparagus spears and increases dramatically toward the base. Small diameter spears contain a higher percentage fiber on a weight basis and are perceived to be tougher than larger diameter spears. Therefore, tall spears of small diameter have a higher percentage fiber and are perceived to be tougher.
Low temperatures (less than 50 to 55 degree F.) during the period prior to harvest results in higher amounts of fiber in spears of equal length. This is due to the fact that growth rate is slowed greater by low temperature than fiber development. It takes longer for spears to reach the height for harvest and fiber development continues. Spears harvested after a period of warm temperatures always have less fiber than asparagus harvested after cool temperatures.
There are several post-harvest factors which affect the further development of fiber after harvest. Most rapid fiber formation occurs during the first 24 hours after harvest and this fiber formation can be slowed down dramatically by cooling the asparagus as soon as possible after harvest. Fiber development will increase more if the storage temperature is too high and the rate of development is quite slow if the temperature is at or near 36 degrees F.
Water loss after harvest tends to increase fiber development. So decreasing water loss by raising the relative humidity, using film wraps or placing the butt ends on a moisture-containing pad will decrease fiber development.