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Knowledge to Grow by Karen Weiland - Asparagus


Rich in iron, calcium, vitamin C and B vitamins, asparagus is one of the first crops to be harvested in the spring and if given the proper planting and care, an asparagus bed can be productive for 15 years or more.

The asparagus bed should be located in a sunny area. Asparagus can tolerate a little shade but the plants will not be as vigorous and full sun helps minimize the threat of disease.

The soil will need to have a pH of 6.5 to 7.5 and be well drained as soggy soil will cause root rot.

It is best to have the soil tested as asparagus will not grow well if the soil pH is less than 6.0 and the levels of potassium and phosphorus are also important to the vigor of asparagus.

Asparagus can be planted mid-April through late May after the soil has warmed up to about 50 degrees. Dig a furrow about 5-6 inches deep.  Apply to the bottom of the furrow about one pound of 0-46-0 (triple superphosphate) or 0-20-0 (superphosphate) fertilizer for every 50 feet of row. This will make phosphorus available right away to the newly planted crowns.  Space the crowns about 1½ ft. apart in the row. I know some people just throw the crowns in and cover them up with soil, but my “it has to be perfect” personality makes me spread the roots out before covering them. I can’t help it – it’s just the way I’m made. 

If more than one row is planted, the rows should be spaced five feet apart. Wide spacing promotes the rapid drying of the fern tops to help prevent disease. After the furrow is filled back in to its original soil level, do not tamp it down as asparagus likes loose soil.

Do not harvest the asparagus shoots during the first year it was planted. The ferns that emerge from the spears produce food for the plant and move it down to the crown for the next year’s spear production.

Asparagus is very drought tolerant and usually does not need any supplemental watering.  However, if rainfall is short after planting, a little watering would be beneficial to the crowns.

Do not cut the fern growth at the end of the growing season.  Leaving it intact over the winter will catch snow for additional soil moisture and insulates the soil covering the crown. Remove the old fern growth by cutting or mowing it off about the first week of April.

As always, Happy Gardening!

The Purdue University Cooperative Extension Service can be reached at 499-6334 in LaGrange County.