Scallion: Indoor, Direct Sow Vegetable
How to Sow and Plant
Sowing Seed Indoors
- For best results, sow seeds indoors 8-10 weeks before last heavy frost.
- Sow thinly and cover with ¼ inch of seed starting formula. Keep moist and maintain a temperature of about 60-65 degrees F.
- Seedlings emerge in 7-14 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.
- After danger of a heavy frost plant the seedlings in the garden when they are about the thickness of a pencil. 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.
- Choose a location in full sun where you did not plant onions the previous year.
- Apply a balanced fertilizer and work into the soil prior to planting. Scallions prefer a pH of 6.0 – 7.0.
- Scallions prefer an organic soil that drains well. Work organic matter into your soil at least 6-8 inches deep, removing stones, then level and smooth.
- Space 2-3 inches apart in rows 1-2 feet apart.
Sowing Directly in the Garden
- Sow directly in the garden in early spring as soon as the soil can be worked and then again in fall.
- Choose a location in full sun where you did not plant onions the previous year.
- Apply a balanced fertilizer and work into the soil prior to planting. Scallions prefer a pH of 6.0 – 7.0.
- Scallions prefer an organic soil that drains well. Work organic matter into your soil at least 6-8 inches deep, removing stones, then level and smooth.
- Sow thinly in rows 1- 2 feet apart and cover with ¼ inch of fine soil. Firm lightly and keep evenly moist.
- Seedlings emerge in 7-14 days.
- Thin to stand about 2 inches apart when seedlings are 1- 2 inches high.
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.
- Ample water is important at all stages of growth, especially when bulbs are forming. Onions are shallow rooted and tend to dry out during periods of drought. The best method to water is by ditch or furrow irrigation. This provides water to the roots while keeping the tops dry. If the tops are regularly wet they are more susceptible to disease.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
Harvest and Preserving Tips
- All onion varieties may be harvested early as scallions. Pick scallions when plants reach 6-8" tall, while the stalks are still white at the bottom and fairly thin.
- Evergreen Long White bunching onions will not form a bulb, so they may be harvested over a longer period as needed. From seeds sown in early spring you may enjoy continuous harvest from June through fall. Pull the largest stalks first to allow room for the others to develop.
- Scallions may be stored in a jar with just the roots in water. They may also be chopped up and stored in a zip lock bag in the freezer.
- Use to season salads, soups and other dishes. Scallions may be served whole on relish trays or cut into pieces for stir fries.
Common Disease Problems
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.
Downy Mildew: This fungus causes whitish gray patches on the undersides and eventually both sides of the leaves. Burpee Recommends: Rotate crops with plants in a different family. Avoid overhead watering. Provide adequate air circulation, do not overcrowd plants. Do not work around plants when they are wet.
Onion Smut: This fungus attacks mostly young seedlings as the new leaves emerge. It causes blister-like lesions near the base of the bulb and streaks on leaves, sheaths and bulbs. The streaks mature into black powdery spores. The fungus stunts the growth of the plants. More mature plants are not as susceptible. It is most prevalent in temperatures under 75 degrees F. The disease lives in the soil for several years. Burpee Recommends: Rotate crops and do not plant in the same area for at least three years. Encourage rapid growth with watering and fertilizer to get plants past the susceptible stage. Some fungicides are effective, Check with your Cooperative Extension Service for recommendations.
Pink Root Rot: A fungus that attacks onion roots causing them to turn a light pink, then red and eventually purple-brown and causing them to shrivel. Infected plants show signs of nutrient deficiencies and drought because the roots cannot take up water and nutrients. Plants are stunted. The disease lives in the soil for several years and thrives in warm temperatures. Burpee Recommends: Plant as early as possible so the bulb of the plant growth will be I cooler temperatures. Rotate crops and plant resistant varieties.
Rust: A number of fungus diseases that rust colored spots on foliage, stalks and husks. Burpee Recommends: Plant early as these diseases tend to be worse later in the season. Practice crop rotation. Remove infected plants.
Common Pest and Cultural Problems
Cutworms: These insects cut off the seedlings at the soil level. 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.
Onion Maggots: These insects attack the bulb rather than the leaves of onion plants. But this feeding habit can be a severe problem even for scallion growers, because the entire seedling eventually dies. If your plants begin to show weakened vigor, dig up a sample plant to see if the bulb looks like it is filled with tunnels. Burpee Recommends: If you see the symptoms, pull all the plants and use what greens you can. Destroy the rest of the plant parts because the flies that produce onion maggots can continue to lay eggs, causing problems for future crops. Practice crop rotation.
Onion Nematodes: Microscopic worms that live in the soil. They inject a toxin into root systems that cause onion tops to turn yellow with blackened tips. The entire plant can become deformed. Burpee Recommends: Pull up affected plants, chop off any usable tops for kitchen use, and discard the rest of the plant. Crop rotation can reduce the amount of damage nematodes continue to wreak on future green onion crops.
Slugs: These pests leave large holes in the foliage or eat leaves entirely. They leave a slime trail, feed at night and are mostly a problem in damp weather. Burpee Recommends: Hand pick, at night if possible. You can try attracting the slugs to traps either using cornmeal or beer. For a beer trap, dig a hole in the ground and place a large cup or bowl into the hole; use something that has steep sides so that the slugs can’t crawl back out when they’re finished. Fill the bowl about ¾ of the way full with beer, and let it sit overnight. In the morning, the bowl should be full of drowned slugs that can be dumped out for the birds to eat. For a cornmeal trap, put a tablespoon or two of cornmeal in a jar and put it on its side near the plants. Slugs are attracted to the scent but they cannot digest it and it will kill them. You can also try placing a barrier around your plants of diatomaceous earth or even coffee grounds. They cannot crawl over these.
Thrips: These are tiny insects that are difficult to see. Plant tops develop silvery-white streaks or blotches and the plants can become deformed. Because the tops are the edible part of the scallion, this foliage disfiguration is more serious than it might be for other edible crops. Burpee Recommends: Blast the tops with a jet of water from your garden hose to get rid of the worst of the problem. It’s best to do this in late morning on a sunny day; wet leaves can lead to the fungal diseases to which scallions are prone. If the problem persists, coat leaves thoroughly with insecticidal soap.
Scallions FAQs
Can I grow scallions over winter? Southern and frost free gardeners can grow scallions all winter.
Do scallions store well like onions? Scallions are used fresh and are not stored like mature onions. They may be kept for a week with their roots in water, or chopped up and frozen.
Can any onion be harvested as scallions? Yes, there are varieties that will only be grown as scallions, but any onion variety may be harvested early for scallions.
What parts of scallions are edible? All parts of scallions are edible, not just the bulb.
What’s the difference between scallions, green onions and spring onions? Nothing! These are all the same type of plant.