Asparagusis one of the first plants that greets us in springtime! It’s a perennial, which means that once it gets established, the tender spears will return year after year. Here’s how to grow asparagus—from planting through harvest.
Thriving in areas with cool winters, asparagus is usually grown from 1-year-old plants or “crowns” (bought at a garden center) but it can also be grown from seed. Plant in early spring as soon as the soil can be worked.
Asparagus plants are either male or female. Female plants produce berries; males plants do not expend energy on berries so they can be up to three times more productive than female plants. For this reason, growing male asparagus plants is preferred.
If you are starting asparagus for the first time, we would plant 10 to 20 asparagus plants per person (15 to 30 feet of row).
Newly-planted asparagus plants may take 2 to 3 years to truly get started and produce, so patience is needed! But then again, the plant can be productive for 20 years or more, producing ½ pound of spears per foot of row in spring and early summer, so we think it’s definitely worth the wait.
After they’re established, however, asparagus are fairly fast producers, sending up new spears every few days for a few weeks in the spring.
Planting Asparagus
Select and prepare your asparagus bed with care — this crop will occupy the same spot for 20 years or more. It can tolerate some shade, but full sun produces more vigorous plants and helps minimize disease. Asparagus does best in lighter soils that warm up quickly in spring and drain well; standing water will quickly rot the roots.
Prepare a planting bed for your asparagus, like this simple raised bed, that’s about 4 feet wide by removing all perennial weeds and roots and digging in plenty of aged manure or compost.
Asparagus plants are monoecious — meaning each individual asparagus plant is either male or female. Some varieties of asparagus, such as Jersey Knight and Jersey Giant, produce all male or primarily male plants, so they’re more productive — male plants yield more harvestable shoots because they don’t have to invest energy in producing seeds. Choose an all-male asparagus variety if high yield is your primary goal.
If you like to experiment, you may also want to grow an heirloom asparagus variety or a purple-stalked variety like Purple Passion. With an all-male variety, 25 plants are usually adequate for a household of four; plant double that amount for standard varieties. (Ardent asparagus lovers recommend tripling these quantities.)
Starting asparagus from one-year-old crowns gives you a year’s head start over seed-grown plants. Two-year-old crowns are usually not a bargain. They tend to suffer more from transplant shock and won’t produce any faster than one-year-old crowns. Buy crowns from a reputable nursery that sells fresh, firm, disease-free roots. Plant them immediately if possible; otherwise, wrap them in slightly damp sphagnum moss until you are ready to plant.
To plant asparagus crowns, dig trenches 12 inches wide and 6 inches deep (8 inches in sandy soil) down the center of the prepared bed. Soak the crowns in compost tea for 20 minutes before planting. Place the crowns in the trenches 1½ to 2 feet apart; top them with 2 to 3 inches of soil. Two weeks later, add another inch or two of soil. Continue adding soil periodically until the soil is slightly mounded above surface level to allow for settling.
HOW TO HARVEST ASPARAGUS
If you have young plants, the season may last 2 to 3 weeks. However, established plants produce longer—up to 8 weeks.
Check your plant every other day for harvest-ready spears. Spears grow quickly and may become too woody before you know it! Once an asparagus spear starts to open and have foliage, it’s too tough for eating.
Harvest spears when they reach 8 to 10 inches in height and between ½ and ¾ inch thick. (Bear in mind that younger, thinner spears will be more tender, so harvest according to your own taste.)
To harvest asparagus, simply cut the spears with a sharp knife or scissors at ground level.
Stop harvesting spears when the diameter of the spears decreases to the size of a pencil.
After harvest, allow the ferns to grow and mature; this replenishes the nutrients for next year’s spear production. Always leave one or two spears.
Cut back asparagus ferns AFTER the foliage has died back and turned brown or yellow. This is usually in the fall after a frost or two. Cut the ferns back to the ground.
HOW TO STORE ASPARAGUS
Asparagus does not keep for very long after it’s picked, so be sure to eat it within two or three days from harvest.
Brush off any visible dirt or give the spears a light washing with cold water before storing. It’s very important to dry washed spears thoroughly; moisture can lead to mold.
To store, bundle the spears together, wrap the stem ends of the spears in a moist paper towel, and place the bundle in a plastic bag. Store in the crisper drawer of your refrigerator.
If you have enough space in your fridge, you can also store asparagus by placing the spears in a cup of water. Keep about an inch of clean water in the cup.