If you’re looking for a vegetable crop that keeps on giving, year after year, consider growing asparagus in your garden! It’s a delicious springtime favorite.
Visit this page for even more perennial crops you can grow.
Contributed by Jodi Torpey, author and Master Gardener.
Growing Asparagus in the Home Garden
Asparagus is one of the all-time great perennial vegetables. This delicious vegetable is a member of the lily family and a sure sign of spring when it starts to appear in the garden. The secrets to successful asparagus growing? Plenty of planting space and patience.
Get Acquainted with Asparagus (Asparagus officinalis)
Take time to plan where you want to place your permanent asparagus bed because plants can live 10 or 15 years or more. Locate the bed in a sunny spot, assuring grown plants won’t block the sun from other parts of the garden.
You’ll also need to consider how much asparagus you’ll want to eat; plan for about 10 plants per person to make sure there’s enough of this vegetable to go around.
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Asparagus can be planted from seeds or roots, but it will take at least two seasons of patient growing before you’re able to harvest bushels of this short-season vegetable.
If planting from seeds, consider the length of time it takes and the number of seeds you’ll need. Home gardeners should look for packets of seeds that specify the average number of seeds.
Seeds may take three weeks to germinate so start seeds them indoors 12 to 14 weeks before your transplanting date. Sow seeds 1/4-inch deep using a sterile seeding mix in individual 2-inch cells.
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Be sure to plan for time to harden off tender transplants to acclimate them to the outside, at least a week and after the danger of frost.
However, most gardeners decide to plant one-year old, dormant asparagus crowns, also called roots, for easier planting and faster results. Order asparagus crowns, from catalogs or buy at the garden center when it’s time for spring planting in your region.
Three Popular Asparagus Varieties
Most asparagus varieties are green but there are delicious purple varieties, too. Look for varieties that are known to grow well in your region or are adaptable to many areas. Some varieties tend to produce more spears and others have built-in disease resistance.
Mary Washington is a favorite asparagus variety that’s known for dependable crops of flavorful green spears. The spears are long, bright green and rust tolerant.
Sweet Purple is an asparagus variety that produces deep purple spears that are thick and said to be sweeter than green asparagus with a nutty flavor and so tender they can be eaten raw. Purple spears turn green when cooked.
Jersey Supreme Hybrid is prized by gardeners for its high quality and heavy production early in the season. A variety that is adaptable to most climates and soils, Jersey Supreme Hybrid offers green spears, is rust resistant and tolerates fusarium.
How to Plant Asparagus
Two keys to ensuring a long-life for your asparagus bed is to spend the time needed to prepare your garden soil and to dig good trenches for planting asparagus roots.
Asparagus plants grow best in soil that has a pH range of 6.5-7.5 or near neutral. If you’re unsure of the pH in your garden soil, send a soil sample for testing or use a reliable method for testing the pH and fertilizer levels. That way you can make soil adjustments before planting.
Wait to plant until the danger of frost has passed and the soil warms to 55-75 degrees and is dry enough to dig in. Never work with soggy soil because of compaction issues.
Dig a flat-bottom trench that’s 12-15 inches wide and at least 12 inches deep; rows should be 36 inches apart (or more).
Select roots that are 1-or 2-years old; each should have 2 or more clusters of buds. (If you decide to plant from seed, start asparagus seeds indoors 12 weeks before planting. Allow 3-4 weeks for seeds to germinate.)
Soak the roots in water or compost tea for about 20 minutes before planting.
Mix the soil from the trench with compost, well-aged manure and superphosphate; fill each trench with about ¾ of the mixture. Spread the roots out radially like a wheel over the mixture, spacing plants about 12 inches apart. Cover with about 2-3 inches of the remaining mixture.
Water the roots well and set up a system for watering such as drip irrigation or a soaker hose.
After shoots appear, cover with several more inches of soil. Continue adding soil in small amounts as the shoots grow, until you’ve filled in the original trench.
Requirements for Growing Asparagus
Another important factor in growing healthy asparagus spears is to keep up with watering and weeding. Try to lift weeds out of the asparagus bed without pulling to keep from disturbing the asparagus’ roots.
Like most vegetables in the home garden, asparagus grows best in full sun, but can also do well with light or dappled shade.
Asparagus needs a loose soil so roots can spread and grow. Be sure to dig deep and wide trenches and make sure to add plenty of organic matter.
Help plants get established quickly over the first two seasons by watering regularly and deeply. Don’t let the asparagus bed dry completely. Use drip irrigation tubing or soaker hose to keep the bed watered. A light layer of organic mulch, such as straw or leaves, will help hold moisture in the soil.
Keep asparagus bed weed-free with a thick layer of organic mulch; handpick any weeds that show up.
Combatting Pests and other Asparagus Problems
Common pests that can harm asparagus include:
Asparagus beetles can be foiled by covering the asparagus bed with row cover cloth and seal the edges tightly with boards, bricks or a layer of soil
Slugs like to chew on young asparagus spears and also on the fronds of mature plants. Set slug traps or use slug bait to keep them away.
Prevent disease problems with good garden practices to keep asparagus plants healthy.
Rust can be prevented by planting varieties that have rust tolerance.
Fusarium wilt causes spears to turn brown and become inedible. Good gardening practices like keeping beds healthy, not overwatering and making sure soil drains helps keep plants healthy. Choose varieties that are known to be Fusarium-resistant.
Gray mold is a soil borne fungus that can show on spears in cool, wet weather. Gray mold looks like brown or gray fuzzy growth on spears. If the weather is especially wet, pull back some of the mulch to give the soil and plants a chance to dry. Overwatering and poor drainage can also cause gray mold.
Can you grow asparagus in containers?
You can try to grow asparagus in containers, but there are no guarantees for large harvests or long-lasting plants. Some experts even advise against it because it doesn’t make practical sense.
If you want to experiment with growing asparagus plants in containers, make sure the container is a large one and has holes in the bottom for drainage and fill with a good quality potting soil. Plant 1-2 year old crowns, soaking them in water before planting
Mound the potting soil, spread the crown’s roots over the soil and fill in the container; water in.
When shoots start to grow, mulch around the plants to help hold in moisture and keep roots cool. In warm weather regions, containers can stay outside; however, in cold regions, containers may need to be moved to keep roots from freezing.
How to Harvest Asparagus
Asparagus planted as one-year roots will be ready to harvest lightly the second year; started from seed wait until the third or fourth year.
Harvest slightly more spears each season to help extend the length of the harvest.
Watch for the young spears to show through the soil and be ready to harvest as they can grow quickly. Cut spears at soil level or ½ inch below the soil when they’re about 8 inches long, are about as thick as your pinkie finger and have tight tips.
NOTE: It’s important to allow some spears to remain in the garden to produce leaves and make food to store in the roots. Pencil-thin spears are a signal to stop harvesting because food stores are almost exhausted.
Sidedress with a well-balanced fertilizer after the harvest to encourage good asparagus growth the next season. An added step is to top-dress the bed with well-aged manure.
Using Fresh Asparagus in the Kitchen
For many gardeners, the taste of fresh asparagus is worth the work of growing it. Asparagus is tastiest when eaten fresh from the garden or lightly steamed.
Spears will keep a few days in the refrigerator if tightly wrapped in plastic or kept like cut flowers, standing with stems in an inch of water with the container covered with a plastic bag.
Some simple ways to prepare fresh asparagus are to steam and toss with some butter and lemon or to roast for 20-25 minutes in a 400-degree oven, brushed with olive oil and a sprinkle of salt.
How to save asparagus seeds
If you want to save the seeds from your asparagus plants, let some of the fronds grow berries and wait for them to turn red. Harvest the berries and set aside to let them dry for a week or more.
Break open the berries carefully and remove the seeds. Store seeds in a cool, dry place until it’s time to start them for the next asparagus planting.