Vigna: Indoor or Direct Sow or Potted Plant Annual
How to Sow and Plant
Vigna may be grown from seed sown early indoors and transplanted outside after frost, or sown directly in the garden in summer, or planted as a potted plant.
Sowing Seed Indoors:
- Nick the seed gently and soak overnight to aid germination.
- Sow vigna indoors 6-8 weeks before the last frost.
- Sow ½ inch deep in seed-starting formula.
- Firm lightly and keep evenly moist.
- Seedlings emerge in 7-21 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 taller. Incandescent bulbs will not work for this process because they will 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.
- If you are growing in small cells, you may need to transplant the seedlings to 3 or 4 inch pots when seedlings have at least 2 pairs of true leaves before transplanting to the garden so they have enough room to develop strong roots.
- 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 the plant’s cell structure and reduces transplant shock and scalding.
Sowing Directly in the Garden:
- Direct sow in well-drained, ordinary soil in full sun after danger of frost. Choose a location with a support on which the vines may climb.
- Nick the seed gently and soak overnight to aid germination.
- Prepare the soil by removing weeds and working organic matter into the top 6-8 inches of soil; then level and smooth.
- Most plants respond well to soils amended with organic matter. Compost is a wonderful form of organic matter with a good balance of nutrients and an ideal pH level, it can be added to your planting area at any time. If compost is not available, top dress the soil after planting with 1-2 inches of organic mulch, which will begin to breakdown into compost. After the growing season, a soil test will indicate what soil amendments are needed for the following season.
- Sow seeds evenly and thinly in rows 18 inches apart and cover with ½ inch of fine soil.
- Firm lightly and keep evenly moist.
- Seedlings will emerge in 7-21 days depending on soil and weather conditions.
- Thin to stand 8-10 inches apart when seedlings are 1-2 inches tall.
Planting in the Garden:
- Select a location in full sun with good rich moist organic, well-drained soil, and a support in which the vines will climb.
- Prepare the bed by turning the soil under to a depth of 6-12, inches removing any debris, and lightly raking as level as possible.
- The addition of organic matter (leaf mold, compost, well-rotted manure) benefits all gardens and is essential in recently constructed neighborhoods.
- Plant on a cloudy day or in late afternoon to reduce transplant shock.
- Dig a hole for each plant, approximately 12-14 inches apart large enough to amply accommodate the root ball.
- Unpot the plant and gently loosen the root ball with your hands to encourage good root growth.
- Place the top of the root ball even with the level of the surrounding soil. Fill with soil to the top of the root ball. Press soil down firmly with your hand.
- Use the plant tag as a location marker.
- Water well.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so 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. For annuals an organic mulch of shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. 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.
- Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer, as higher rates may encourage root rots.
- Remove spent flower heads to keep plants flowering until fall.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Remove plants after they are killed by frost in fall to avoid disease issues the following year.
- Vines can reach 10 feet; be sure to provide supports.
- Flowers are fragrant and good for cutting.
- Plants are perennial in warmer areas.
Common Disease Problems
Anthracnose: This is a fungus disease that causes circular spots on foliage that are slightly sunken. The spots enlarge and turn black. Extended periods of heat and humidity facilitate anthracnose growth. The fungus overwinters in diseased plant debris. Burpee Recommends: Provide sufficient space between plants for good air circulation, avoid overhead watering which can spread the fungus spores, keep a clean garden, remove and discard all diseased plant material and rotate crops. Use a mulch to prevent spores from splashing from the soil onto plants.
Blight: This causes brown concentric rings to appear on the lower leaves. The spots coalesce; the leaf turns brown and may drop off the stem. Leaf drop moves up the stem. This fungus overwinters in plant debris and weeds. Greasy, greenish-black, water soaked spots appear on the lower leaves. The spots enlarge and if the weather is wet they will look mildewed. Fruits develop dark rough spots. Rainy or cloudy days with temperatures of 70-80 degrees F and nights at 40- 60 degrees F provide ideal conditions for the rapid growth of this fungus. It is retarded by hot dry weather. The fungus is air-borne and can spread from diseased plants growing nearby. Burpee Recommends: Practice good garden hygiene at the end of the season and discard, do not compost, possibly diseased plants. Space plants to allow for adequate air circulation. Avoid overhead watering which may spread fungus spores.
Cercospora Leaf Blight: Small flecks develop a yellowish halo appear on the leaves and turn brown and coalesce. They cause the leaves to wither and die. Burpee Recommends: Remove infected plants and destroy all plant debris. Rotate crops.
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.
Powdery Mildew: This fungus disease occurs on the top of the leaves in humid weather conditions. The leaves appear to have a whitish or greyish surface and may curl. Burpee Recommends: Avoid powdery mildew by providing good air circulation for the plants by good spacing and pruning. Contact your Cooperative Extension Service for fungicide recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps which feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Armyworm: Holes in leaves can be singular or clumped together. Leaves can become skeletonized. Egg clusters may be evident on foliage with a cottony or fuzzy appearance. Young larvae are pale green and adults are darker with a light line along the side and pink underside. Burpee Recommends: Introduce natural enemies to the area.
Thrips: Thrips are tiny needle-thin insects that are black or straw colored. They suck the juices of plants and attack flower petals, leaves and stems. The plant will have a stippling, discolored flecking or silvering of the leaf surface. Thrips can spread many diseases from plant to plant. Burpee Recommends: Many thrips may be repelled by sheets of aluminum foil spread between rows of plants. Remove weeds from the bed and remove debris from the bed after frost. Check with your Cooperative Extension Service for pest controls.
Vine Weevil: This insect cuts irregular notches in leaf margins and grubs feed on plant roots, sometimes causing the death of the plant. Adults are approximately 5/16 inch long, dull black with dirty yellow marking on the wing cases. The grubs are c-shaped, 3/8 inches long, with light brown heads. Burpee Recommends: Handpick adults at night, shake the plants over newspaper to dislodge them. Check under pots where they hide during the day. Check with your Cooperative Extension Service for pesticide recommendations.
Can I grow vigna in a container? No, the vines are just too large.
Are vigna flowers good for cutting? Yes they make great cut flowers, and are fragrant too.
Why do I see ants on my vigna flowers? Vignas are pollinated by ants so it is normal to see them on the flowers. If they are on the plants and they are not in bloom, you may have aphids, which attract ants.
Is vigna a perennial? Plants are tender perennials and will survive outdoors in zone 10.
Why hasn’t my vigna bloomed? These tend to bloom fairly late in the summer, if could just be too early. Otherwise it may be in too much shade, or have too much nitrogen in the soul from fertilization.