The Q&A Archives: Shrinking asparagus bed

Question: After a hard winter about half of the crowns in my asparagus bed appear to have died and the rest are spindly. I've watered them well. What can I do to rejuvenate my bed? Jane Moore Santa Ana, CA

Answer: Asparagus is hardy, so it's probably not the rough winter. If you've been watering diligently, it's more likely a soil fertility problem, says Dennis Pittenger, environmental horticulturist at the University of California, Riverside. Asparagus needs an inch of water a week during the growing season plus proper fertility to grow well in southern California, he says. For your bed, I'd recommend applying a high-nitrogen fertilizer such as blood meal or ammonium sulfate at the rate of one to twopounds per 100 square feet as new spears break ground. In midsummer, side-dress your planting with the same fertilizer and a few shovelfuls of composted manure per crown, he adds. Replace the crowns that have died out with one of the improved Universityof California disease-resistant hybrids such as UC 72 or UC 157. If the spears still don't increase in size, the plants may be struggling against Fusarium wilt disease in the soil. Try starting over with one of the new varieties in a spot that hasn't had asparagus before. In February, work the soil at least a foot deep. Add a few shovelfuls of composted manure per crown and use drip irrigation during the growing season (and in winter during drought). Side-dress the plantings as described above. By the second spring you can start harvesting spears for a two- to four-week period or as long as their diameter is larger than a pencil. If you don't have a new location, solarize the soil in the bed to kill the disease. Remove the plants and weeds, till the soil, rake it smooth and moisten it. Then lay 4-mil-thick clear plastic and leave it in place so the ground can bake under bright sun for four to six weeks. You can replant immediately.

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