Asparagus Fern: Annual potted foliage plant, it is for ornamental use.
How to Sow and Plant
Asparagus fern may be grown from seed sown directly in the garden or from transplanted seedlings
Sowing Seed Indoors:
- Start asparagus seeds indoors 8-12 weeks before outdoor planting date in spring in peat pots, plastic pots or trays. At least 2 x 2 inch cells works best.
- Sow seeds 1/4 inch deep in seed-starting formula cover with fine soil
- Keep soil moist at 70-75 degrees F
- Seedlings will emerge in 10-14 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow. Incandescent bulbs do not work because they get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- Seedlings should be 4-8 inches tall
- Transplant after all danger of frost has passed
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens cell structure and reduces transplant shock and sun burn.
- Space transplants 10 to 12 inches apart.
Sowing Directly in the Garden:
- Direct sow seeds in in spring after all danger of frost has passes
- Asparagus ferns prefers full sun and a good organic well drained soil.
- Prepare the soil by removing weeds and working organic matter into the top 6-8 inches of soil; then level and smooth.
- Sow seeds evenly and thinly and cover with 1/4 inch of fine soil
- Firm soil lightly with your hand, water and keep evenly moist.
- Seedlings will emerge in 10-14 days at 75 degrees F, a little longer if the soil is cooler.
- Thin seedlings to about 10-12 inches apart when seedlings have at least two sets of leaves.
Planting Seedling Plants in the Garden:
- Dig a hole for each plant large enough to amply accommodate the root ball.
- Set plants in the bottom, spacing centers 10-12 inches apart
- Place the top of the root ball approximately ½ inch below the level of the surrounding soil.
- Fill with soil to the top of the root ball.
- Press soil down firmly and water.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, control them by either cultivating often or use a mulch to prevent their seeds from germinating.
- Mulches also help retain soil moisture and maintain even soil temperatures. Put down a layer of newspaper 5-10 sheets thick between the rows (soak the papers in water first, so they won't blow away) and then cover the newspaper with dry grass clippings, aged bark mulch, weed-free straw, etc. Always keep mulches off of plants’ stems to prevent possible rot.
- Keep plants well-watered during the growing season, especially during dry spells. Plants need about 1 inch of rain per week during the growing season. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- Do NOT cut plants back after harvest, allow them to fern and grow as long as they can before frost. They will become quite large. They need the green foliage to make food for themselves to make strong plants next year.
- Have your soil tested for fertilizer recommendations. Fertilize after harvest and in late summer.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- In late fall cut tops to ground level when they have turned brown. In cooler climates mulch the ground with evergreen branches or straw after the ground freezes for extra protection. Remove this winter mulch in early spring.
Harvesting and Preserving Tips
- Do NOT harvest asparagus the first year. Allow the plants to grow and make food to store in the roots for stronger plants the following year. When plants are two years old you can harvest them for a short period. In the third year you can harvest for four weeks.
- Harvest when new spears emerge in spring. Harvest when spears are about ½ inch wide. On average spears should be 6-8 inches tall.
- Using a sharp, clean knife, cut young spears at ground level and set in water with the cut side down until you are ready to store the spears. Some gardeners prefer to snap the stems, but this can cause damaged tissue which can result in disease issues.
- Harvest frequently before spears start to leaf out.
- Do not harvest spears less than ¼ inch in diameter.
- Prepare as soon as possible as fresh asparagus is best.
- Asparagus also freezes well for later use. Sort the spears by thickness and “blanch” smaller ones 1 ½ minutes, medium for 2 minutes and thickest for 3 minutes. To do this, drop the spears into boiling water for the recommended time, then plunge into cold water to stop the cooking, drain and store in freezer bags or vacuum bags.
Common Disease Problems
Crown Rot: Caused by a soil borne fungus that rots the stems at the soil line. It interferes with the plants’ ability to take up nutrients and water and plants will decline and die. Burpee Recommends: Do not plant asparagus in the same area for at least eight years.
Fusarium Wilt: A soil borne disease that causes the roots to rot. The infection can enter the plant through wounds caused by cultivation, insects or harvesting. The spears will shrivel and ferns turn yellow and wilt. There is no cure for the disease. Burpee Recommends: Some varieties are tolerant to the disease. Do not plant asparagus where this problem has occurred.
Purple Spot: This fungus causes tan to brown lesions to develop on spears. They may coalesce and cause defoliation. Burpee Recommends: Contact your Cooperative Extension Service for fungicide recommendations.
Common Pest and Cultural Problems
Asparagus Aphids: These are powdery gray-green colored sucking insects that inject toxins into the plant as they feed on the undersides of leaves causing the plant to be stunted and have abnormal growth. Burpee Recommends: You can wash them off with a strong spray, or use an insecticidal soap.
Asparagus Beetle (Common): The common asparagus beetle adults are ¼ inch long with black wings with red margins and three large yellow squarish spots. The larvae are blue-gray with black heads. They feed on the ferns and weaken the plants. The beetles are active, but shy, and may drop to the ground or to lower leaves when disturbed, and they make a squeaking noise when they are caught. They overwinter as adults and congregate on the young shoots when they emerge in spring. They lay rows of three to eight black eggs at the ends of the spears and on the foliage. The eggs hatch in a week and the young larvae feed on the leaf tips to feed. After two weeks they drop to the soil and change into adults. There are several generations throughout the growing season. The larvae excrete a black fluid on the tips, and adult feeding can damage the buds and stems of the young shoots causing them to be woody and crooked. Burpee Recommends: To control, hand pick, or knock the larvae to the ground by brushing the plants with a broom. Contact your Cooperative Extension Service for pesticide recommendations.
Browning Foliage: This can result from drought stress, particularly in mid-summer. Burpee Recommends: A drip irrigation watering system and mulch can help control drought stress.
Cutworms: These can feed on the spear tips and sides. The brown to pale yellow larva can be 2 inches long and lives in the soil. The adults are moths that lay their eggs in weeds. Burpee Recommends: Place a paper cup collar (use a coffee cut with the bottom cut out) around the base of the plant. They are usually mostly a problem with young seedlings. You can also control by handpicking and controlling weeds, where they lay their eggs.
Twelve Spotted Asparagus Beetle: This beetle is reddish orange with twelve black spots on its back. Overwintering adults cause damage by feeding on the tender spring shoots. The eggs are yellowish to light green and are attached by their sides to the leaves. The young larvae feed on the berries of the female plant. Burpee Recommends: Hand pick and contact your local Cooperative Extension Service for pesticide recommendations.
Asparagus FAQs
Do Asparagus Ferns make a good potted plant? Yes it makes an excellent container or hanging basket plant.
Is Asparagus Fern hardy in my area? Asparagus fern is usually grown as an annual it is only hardy in zones 9-11.
Do Asparagus Fern have thorns? Yes Asparagus Ferns have small thorns about 4mm long.