Do you want to learn how to grow asparagus? Well, we will tell you everything you need to know about growing asparagus.
Our Asparagus Growing Guide will cover everything. Starting from choosing the right variety, planting, site selection and soil preparation, harvesting, growing, and care.
We will provide you with instructions that will help you to tackle specific problems such as pest attacks and diseases that affect plant growth, flowering, and fruit formation.
Table of Contents
About Asparagus Plants
For an early-season treat from the vegetable garden, try planting asparagus. This hardy perennial crop is easy to grow but requires a one-to two-year wait after planting before the first harvest.
Asparagus grows in Zones 2 through 9 but is less productive in the Deep South. Warm winters keep the crowns (perennial roots) from storing the reserves needed for strong spring growth.
Let us learn how to grow asparagus step by step…
1) Choosing The Right Asparagus Plant
Choose cultivars resistant to rust and Fusarium wilt. Also, look for new hybrids such as ‘Jersey Knight’ that produce mostly male plants.
Male plants yield more than female plants because females put energy into making berries instead of spears. West Coast and southern gardeners should look for heat-tolerant cultivars.
a) Growing Asparagus from Crowns
It’s easiest to establish asparagus by planting one-year-old crowns. They should produce harvestable spears the year after planting.
Select large crowns with thick roots and well-formed buds. Crowns may be available at your local garden center. For a wider range of cultivar choices, order from a mail-order company.
b) Growing asparagus from Seeds
Starting asparagus from seed is cheaper than buying crowns. It requires more care and a two-year wait until harvest. However, stands produced from seed often yield better than stands start-ed from crowns.
2) Site and Soil
A well-prepared asparagus bed can produce for 20 or more years. Separate your asparagus patch from your annual vegetables so you won’t accidentally till or dig it up.
Choose a site with:
- At least half a day of sun.
- Moderately rich sandy or loam soil.
- pH between 6.5 and 7.5.
- Areas where water puddles on the soil surface.
- Sites exposed to strong winds.
- Sites where asparagus grew previously.
3) Preparing Site for Plant Asparagus
- Remove all stones and perennial weeds from the site.
- Work in 10 to 20 pounds of compost per 100 square feet.
- Apply 5 pounds of rock phosphate or calcium phosphate per 100 square feet to supply phosphorus.
- Roots will rot in soggy beds. If you have clay soil, prepare raised planting beds to ensure good drainage.
a. When to plant
In mild-winter areas, plant crowns in the fall. In colder regions, plant in the spring when soil temperatures reach 50°F and night temperatures are above 35°F.
b. How much to plant
Plant 20 to 40 plants per person, depending on your appetite for asparagus.
c. Starting plants indoors
In short-season areas, start seeds indoors, as shown in the above illustration.
d. Planting asparagus crowns outdoors
- Make small mounds of compost 1.5 to 2 feet apart in the bottom of the trenches.
- Drape the long roots of each crown over each mound.
- Dig 1-foot-wide trenches 6 to 8 inches deep and 4 feet apart in the prepared planting area.
- Cover the crowns with about 2 inches of soil and gently tamp it down. Continue adding 2 inches of soil every two weeks until the trenches are filled and the soil is slightly mounded over the top.
- Sprinkle 1 to 2 pounds of alfalfa meal per 100 square feet over the finished beds. Mulch with 6 to 12 inches of shredded leaves or other organic mulch.
- Plan to water the young stand weekly for the first two years of growth whenever the weather is dry.
e. Planting seeds outdoors
- In mild climates, plant seeds outdoors as soon as frost danger is past.
- Sow two seeds per inch in a nursery bed—a specially prepared temporary bed with good quality, fine soil.
- Sow seeds 1/2 inch deep in rows 18 inches apart. Germination takes about 30 days.
- Add radish seeds to the rows as you plant; they emerge quickly and serve as a row marker.
- Thin the seedlings to 4 inches apart when the plants are 3 inches tall.
- Transplant nursery-bed plants to a permanent site in late summer or the following spring.
5) Seasonal Care
a. Caring for asparagus during spring
Protect from frost: Late frosts can turn spears brown and soft. Cover emerging spears with leaf mulch or a tarp when frost is predicted.
Cover with floating row cover: If you’ve had past infestations of asparagus beetles or beet armyworms, cover beds with row cover for the harvest period.
Blanch spears: If you want white asparagus spears, mound organic mulch over the beds as the spears develop.
Allow first spears to grow: If crown rot has weakened your patch in the past, don’t cut the first spear that emerges from each crown. It will grow to full size and provide food to the roots during the harvest period, helping to keep the plant-strong.
Harvest daily in hot weather: Temperatures above 90°F can cause leaves on spears to sprout prematurely. Harvest daily to avoid this.
Apply mulch: After the harvest is over, spread a 6- to 12-inch layer of leaf mulch.
b. Caring for asparagus during summer
Clear weeds: Pull weeds that emerge through the mulch until the plants are large enough to smother them.
Water as needed: Keep the soil evenly moist. To test soil moistness, squeeze some soil in your hand. It should form a loose ball without sticking to your fingers; if it doesn’t, you need to water.
c. Caring for asparagus during fall
Cut down fronds: After the fronds die, cut or mow them off at ground level. Destroy or dispose of old foliage.
Apply compost: Spread 10 to 15 pounds of compost per 100 square feet.
Mulch: In northern areas, renew leaf mulch to protect the roots during winter.
6) Harvesting Asparagus
Harvest asparagus spears in early spring when they are 6 to 10 inches high and the tips are firm, with tight bracts. Don’t harvest spindly spears.
In the first year of harvest, pick only for 2 weeks. Extend the harvest each year, until you are harvesting for about 8 weeks (12 weeks in California).
Once a bed is in full production, pick about every three days. When the weather warms and the crop grows fast, you may need to harvest twice a day to keep up with production.
It’s best to eat or preserve asparagus right after picking. To store spears up to one week, place them upright in a shallow tray of water in the refrigerator.
7) Propagating Asparagus
If you’re growing a standard cultivar, you can collect berries from female plants before the first fall frost. Crush the berries in a bag, then soak them in water to wash away the pulp. Collect seeds that sink while soaking; air dry them for a week before storing.
8) Solving Asparagus Problems
Use this table to identify problems in your asparagus patch. Scan the list of symptoms to find the description that most closely matches what you see in your garden. Then refer across the page to learn the cause and the recommended solutions.
For some pest problems, by the time you see the damage, there is little you can do to fix things in the current season.
|1.||Slender, weak, or small spears||Young plants, Poor soil, Excessive harvesting||It is normal for first-year spears to be slender; do not harvest the first year after planting. If older stands produce weak plants, fertilize them well.|
Next season, shorten the harvest period to allow plants to recover.
|2.||Brown scars or tunnels just beneath the skin of spears||Asparagus miners||Destroy any spears with miners. Plan to pull up old stalks in fall and burn. Miner infestations often increase infection by Fusarium.|
|3.||Spindly spears with dark sunken areas at or below soil level||Fusarium wilt||Remove and destroy affected plants. Try a single application of rock salt (2 lb. per 100 sq. ft.). If the damage is severe, replant in a site not used for asparagus for at least 8 years, using Fusarium-tolerant cultivars.|
|4.||Spindly spears turn brown at soil line and rot||Crown Rot||Remove and destroy affected plants. Replant disease-free stock, preferably in raised beds. Test soil pH and adjust if needed to keep pH above 6.0.|
|5.||Dark stains on spears; spears chewed by small, orange or blue-black beetles||Asparagus beetles||Damaged spears are edible. Handpick and destroy beetles, larvae, and eggs (laid on stems), or wash them off with a strong spray of water. If beetles are numerous, spray with pyrethrins or rotenone. Remove and destroy old stalks in fall.|
|6.||Small, reddish spots on spears, stalks, and leaves ||Asparagus rust||Spray sulfur at first sign of disease to reduce severity. Strengthen plants with good growing conditions. Cut and destroy stalks in fall. Where infections are severe, replant with resistant cultivars.|
|7.||Silvery or grayish spears and stalks||Onion thrips||Damaged spears are edible. These tiny sucking insects are barely visible to the naked eye. If infestation is severe, spray neem, pyrethrins, or insecticidal soap.|
|8.||Leaves chewed; fronds stripped of leaves||Beet armyworms||These green caterpillars are also called the asparagus fern caterpillar. Handpick caterpillars. If a large stand is infested, spray BTK or neem.|
|9.||Short, stunted plants; tiny, powdery green insects on ferns||Asparagus aphids||Wash aphids off plants with a strong spray of water. For severe infestations, spray neem or pyrethrins. In the fall, remove and destroy ferns. or till them into the soil.|