Scallions are fresh, fast, and fabulous in salads, stir-fries, and savory tarts. Also known as green onions or salad onions, scallions are harvested before they reach maturity and can be grown year-round indoors.
Fast-growing plants like lettuce that you plant directly in the ground get tall quickly but have a short harvest window of just a few weeks. Indoor onion plants grow slowly over several months with an even longer harvest window than outdoor varieties.
Scallions are also one of those crops that can be sown in late summer to give one of the earliest harvests next spring. Here's how to grow scallions from seeds indoors, so you always have these tasty vegetables on hand for cooking or snacking.
What are Scallions?
Allium fistulosum, also known as green onions, is called bunching onions or scallions. Scallions are produced from specific cultivars of the bulbing onion and have a mild flavor.
Green onions look similar to the traditional onion known as Allium cepa. They have tall, green stalks that are usually 1 to 2 feet tall. Scallions have slender white bulbs at their base that do not get large enough to form an onion.
Scallion Varieties to Try
There are several scallion varieties. These include:
Guardsman scallions are known for their slow bolting. They grow to about 20 inches tall and have green leaves that are blue-green at the base. The white bulb is slender, cylindrical, and has a mild flavor. This variety takes 50 days to grow, and it straddles the line between a spring onion and scallion for taste.
Evergreen White Bunching
Evergreen White Bunching is a green onion that grows best in the spring and fall. It has thick, blue-green leaves with white bulbs at its base. The plant grows up to 12 inches tall and keeps growing every 45 days until frost. This scallion takes around 60 days to grow from start to finish.
Nabechan is an oriental green onion that grows about 8 inches tall with white stalks and blue/green leaves. It takes around 60 days for these scallions to grow. It's a Japanese variety prized for its flavor.
Tokyo Long White Bunching
Tokyo Long White Bunching is a white scallion that grows to about 12 inches tall. The leaves are long and slender, with a white bulb at the base. It takes around 90 days for these scallions to grow. This variety is also known as Welsh Onion or Scallion.
Red Beard is a red scallion that grows to about 12 inches tall. The leaves are long and slender, with a white bulb at the base. It takes around 90 days for these scallions to grow.
How to Grow Scallions from Seed
You can plant seeds indoors about 8 to 10 weeks before your projected last frost date. You can also direct sow in the garden once the threat of frost has passed. Sow your seed about 1/4 inches deep. Other onions may have slow and poor germination. So, the most important element scallion seeds need is constant moisture, making starting them indoors a good choice.
Seedlings emerge in one to two weeks. Once you have grown, thin the seedlings to about 2 inches apart. For a continual harvest, plant new crops every four weeks.
Potting and Repotting Scallions
Scallions can be grown in pots or containers on a sunny windowsill. Use well draining soil and organic potting mix when growing scallions in containers. Cover the seeds with a loose layer of soil and water them thoroughly. Make sure you keep the soil moist and not soaked.
If you want more instant gratification, then scraps and starts are two methods that are too quick for growing green onions. You'll have scraps left over when you buy and use scallions from the grocery store. Get your container and rich potting soil. You can make your own compost to add some nutrients to the soil.
The scallions leave between three and four inches of the white bulb intact. Make 1/2 inch deep holes an inch apart in your container and drop the scrap in. Keep the soil moist and not soaked.
The final method of growing green onions is to get the starts from your local nursery. Take your starts off from the soil and gently shake off excess dirt so you can see the roots. Get a container and fill it with rich potting soil. Trim your roots back until they're two or three inches long.
Your pot should be narrow and at least six inches deep. Make sure your container is in an area that will get direct sunlight. Keep the soil slightly moist and don't overwater because this allows for decay and diseases. This way, you should be able to harvest and plant more scallions after every three weeks.
Give your scallion plants at least six hours of direct sunlight per day. If you're planting indoors, put them by a south-facing window. When planting outside, put them in an area that gets the most sunlight. Plant them in a partial shade if you don't have that area.
Scallion plants prefer rich, sandy soil with sharp drainage and a slightly acidic to neutral soil pH. Amend your soil with organic matter to ensure good drainage. If you live in heavy clay soils, add sand or gravel to the mix. Consider doing some DIY soil tests to get the best for your scallions.
Fertilizing Green Onion
Fertilize green onions with a balanced fertilizer like 10-10-10 when you first plant them and again every four to six weeks. Fertilizer rich in nitrogen such as fish emulsion is ideal for green onions because it will provide the plants with a steady stream of nutrients over an extended period and keep them green and growing.
For a longer-term solution, use granular fertilizers released slowly into the soil. You can also top-dress with rich compost.
Scallion plants have a shallow root system, so regular watering is important. Keep the soil moist and do not let it dry out. While this may seem difficult in areas with long periods of hot, dry weather, you can greatly reduce the amount of time between watering by mulching with straw or pine bark nuggets. You can also try planting scallions in a raised bed to improve drainage and provide better access to water.
If you're growing scallions in a container, make sure the pot has drainage holes and keep it evenly moist; they will likely need more frequent watering than they would get in your garden. A well drained soil also protects foliage from excess moisture, which can cause rot.
Temperature and Humidity
Allium cepa grows best when the air temperature is between 68°-78°F. If you're growing scallions from seed, place a heat mat over your flats to ensure even soil temperatures around 45°F.
Ensure your flats get at least 6 hours of light each day for optimal germination rates and shoot growth. Scallion seeds do not mind humid conditions as long as they have good drainage to prevent rot and other diseases.
Pruning Scallion Plant
Most of the time, pruning is done by removing wilted leaves, which should be left until it's time to pick them. If your green onion bolts to seed and you want to prevent seed drop, trim off the flower stalk. You may also experience leaf wilt during flowering.
Once you notice that the flowers are fading, cut the stalk once it begins to droop and set it somewhere to allow the head to dry out and the seeds to drop out of the flower.
One method of propagation is bulbs or sets. The best way to use sets is by planting them in late fall and overwintering them in the garden. In the spring, they'll start pushing up new growth. You can also use nursery starts of Allium cepa and plant them to achieve the green onion stalks.
Remember that only Allium fistulosum will produce green tree onions without onion bulbs. True scallion has a milder flavor than A. cepa, which has a stronger onion flavor.
Harvesting and Storing Scallions
Start picking your spring onions once they reach a usable size. The best time to do this is when the bulbs are white and have a diameter about the size of the pencil, but even smaller sizes can be harvested.
You can dig up the whole plant if you plant to eat the mild white bulb or snip the stem off just above the soil level and allow it to continue growing. When growing traditional bulb onions as green onions, harvest the green leaves earlier and use them like scallion plants.
Store your green onions in a partially filled jar in your fridge with enough moisture to keep the leaves from wilting. If you harvest stalks without bulbs, store the stalks wrapped in a paper towel in a plastic storage bag. You can also slice and refrigerate them in a plastic bag.
To freeze your onions, rinse them off and thoroughly pat or air dry them before freezing. Their texture will be a bit mushy when they thaw out, so it's best to use them in cooked food rather than as a garnish. Dehydrating the stalks and grinding them into a powder is a great option for long-term storage if you have a dehydrator.
Common Pests and Plant Diseases
Thrips and aphids are common pests in onion crops and can be remedied by using a strong stream of water from a hose. If they persist, use insecticidal soap or neem oil or treat severe infestations with pyrethrin. Cutworms, onion maggots, onion nematodes, slugs, and allium leaf miners are also potential pests but can be dealt with by using prevention methods such as crop rotation or organic mulches.
You can also use a beer trap to trap slugs and snails. As long as the trap is deep as a pie pan, snails and slugs will be attracted to the beer's aroma, which will be deep enough to drown them.
Botrytis neck rot, purple blotch, and Fusarium basal rot are the most common onion diseases. They can be controlled by planting disease-resistant varieties and spacing plants properly. You can also remove infected plants and leaves, and use a fungicide.
White rot can also cause mold or rot at the base of the plant and yellowed, wilted leaves. If you notice the diseased plants, remove and dispose of them. Avoid planting Allium in that location for a couple of years. Practice crop rotation for the benefit of your plant's health.
FAQs on How to Grow Scallions
Do green onions grow back every year?
These spring onions are biennial and can live for several seasons. They'll come back after being cut down but won't regrow if the bulbs die or are frozen.
Final Thought on How to Grow Scallions
As you can see, growing scallions is easy and can be done in almost any climate. With a little bit of care, you'll have plenty of these delicious onions to enjoy all season long. So, what are you waiting for? Get started on your scallion garden today.