As I write this it’s Mother’s Day Sunday, and this morning I was delighted to see some fat asparagus stalks ready for harvest in our asparagus patch! Many years ago we built a raised bed specifically for asparagus, and now we’re getting a dependable crop. Our bed is circular, with two dozen asparagus plants spaced around the perimeter. This allows us to harvest, without compacting the soil in the bed, just enough spears each day for our family’s dinner. We planted daylilies and Black-eyed Susan in the center of our bed, so it’s showy after harvest time.
Asparagus is a perennial that will grow larger and more productive each year and produce for many years with almost no maintenance, if you plant it properly. You can harvest handfuls of crisp, sweet stalks all during spring from an established patch. You just have to invest some time and effort to get your plants started, and wait patiently for a few years for them to get established before you start to harvest.
One-year roots, called crowns, are available online or by mail order. A common mistake with asparagus is to underestimate how many plants you need. Remember that while each plant may produce a pound or more of fresh spears each season, there are only one or two spears per plant on any given day, at most. If you want to cut a family-sized harvest into your cooking pot, YOU’LL NEED AT LEAST SIX PLANTS PER FAMILY MEMBER. During asparagus season we harvest every morning; if there aren’t enough stalks for dinner we have to refrigerate them until we have enough.
Planting holes should be one foot deep and wide, spaced two feet apart. If you are planting in trenches, rows should be spaced five feet apart. Giving the plants lots of room helps prevent fungus diseases by letting air circulate to keep them dry. Good drainage is important; asparagus won’t perform in waterlogged soils; soggy ground can cause root rot.
Sprinkle some 0-21-0 (triple super-phosphate) fertilizer in the bottom of the planting holes or trench before planting. Fill half full with compost or well-aged manure, sprinkle on some Espoma Plant-Tone or Garden Tone, and plant the roots so that the base of the plant (root crown) is about four inches below ground level. Only fill to the tips of the plants; if your plants don’t have stalks yet, wait for them to grow before backfilling around them. Feed your plants generously every year with a high-phosphate fertilizer.
The best weed control is mulching. You can use straw, composted leaves, or grass clippings for this purpose. We use pine bark nuggets, because they allow air to reach the plant roots. If you have a problem with perennial weeds, after harvest is over you can cut all the asparagus stalks to the ground and then spray the row with Roundup to kill the weeds. Another way to slow the growth of weeds is to plant broad-leafed vines like squash, pumpkins or cucumbers between the rows of asparagus.
Wait at least a year before you harvest. Let the plants grow all season, fertilizing occasionally and mulching to prevent weeds. After frost kills the tops cut them off. Repeat this the second year. Start harvesting, but only cut spears that are at least as thick as your finger. After harvest is over let the remaining stalks grow tall so they can replenish the roots.
Asparagus beetles chew on the fern-like leaves, causing the stem to turn brown and reducing the yield the next year. If you see Asparagus beetles, spray the ferns with an approved insecticide. For disease prevention, spray with an approved fungicide on a 7 to 14 day schedule beginning when the ferns reach a 3 to 4 foot height and continuing until mid-September.
In our asparagus patch we have equal numbers of Jersey Knight and Purple Passion plants. Jersey Knight produces a bumper crop of large, fat spears, typically 5/8-inch in diameter, bright green with deep purple tips. One of the easiest varieties to grow, they have terrific vigor that makes these plants come back stronger every year. Purple Passion spears are larger and more tender than green asparagus, and stringless. The whole spear can be cooked without wasting the butt. Jersey Knight yields almost twice as heavily, but the Purple Passion spears are fatter and tastier by far.
Steve Boehme and his wife Marjorie own GoodSeed Farm Landscapes, a design-build landscape/hardscape installer specializing in outdoor living spaces. More information is available at www.goodseedfarm.com or call GoodSeed Farm & Garden at (937) 695-0350.