March 25, 2010 at 9:43 a.m.
When you plan for starting an asparagus bed you should plan as you would for starting an orchard. It means that it could be there for ten to thirty years, or more. The mistakes you make in the plan you must live with for years so part of the planning should include a soil sample as a starting point.
In Minnesota, asparagus can be grown on sandy soils to heavy clay loam. However the highest yields are obtained on deep, sandy loam. The roots can penetrate to at least six feet deep in loamy soils. Shallow soils no matter what the texture should be avoided. A high water table or the presence of an underneath hard pan is not good because asparagus roots cannot tolerate wet feet.
Garden catalogs may offer many different varieties of asparagus roots but one must be sure they are winter hardy for our area. We offer Mary Washington asparagus because it is rust resistant and the spears are harvestable over an extra long cutting period. There are some new varieties that may be dependable but we are satisfied with Mary Washington.
When you are ready to plant, dig a trench about eight inches deep and wide enough to be able to spread the roots. If you have never seen an asparagus root, they look like an octopus with many legs. Space the asparagus eighteen inches apart and if you have more than one row, leave four feet between the rows.
Cover the roots with at least two inches of soil and continue to fill in the trench as the shoots grow. This is much the same way some do with dahlias and gladiolas. Don't bury the green shoots completely and continue to fill the trench so that it will be filled by the end of the first growing season. This may pose a problem, as the soil at the edge of the trench may get lumpy due to weather conditions.
Planting the asparagus may seem like a difficult task because the roots need to be planted so deep, but that's the easy part. Watching so weeds or insects don't take over is much more difficult. Whenever the weeds appear remove them immediately. If you mulch the asparagus, be sure to use seed-free straw or grass clippings.
One of the mistakes gardeners make is to harvest the stalks too early. We offer roots that are two years old and should not be used until they have been in the ground for three years more. The third year you can make one cutting and not after July 1st. This is to protect the roots from winterkill.
The next class in our spring series will be another show and tell at the Al and Judy Olson vineyard near Wild Mountain. The class will be on Saturday, March 27 from 9 a.m. - noon and the cost is $5 per person. Preregistration is encouraged and for more information call the Extension Office at 213-8901.