Onions are such a versatile vegetable to have for cooking. I use them in almost every recipe. Green bunching onions are especially tasty.
If you are looking for a way to eat more organic food, save money and be more self-reliant this is your answer – grow tasty onions in grow bags on your patio.
Onions can be started in cool weather and take approximately 110 days to grow to maturity. Bunching onions produce clusters of long, slender onions that can be separated and are best harvested when they are pencil size, which takes 60-75 days. You can begin harvesting as soon as they reach the size you want. No need to wait for maturity. They like well-fertilized, moderately moist soil.
How to Grow Onions From Seed
Start onion seeds indoors 8-10 weeks before your last frost date (look up yours here). I use seed trays to grow onion seedlings. .
- Fill the seed trays with pre-moistened seed starting mix, sprinkle the seeds evenly on top of the soil, mist with water, cover with 1/8-inch of seed starting mix, and press down gently to be sure the seeds are in contact with the moist soil.
- Once the seeds sprout, remove the humidity dome, and place under lights in a cool location.
- Keep soil evenly moist. Water with diluted fish emulsion or compost tea every two weeks. Trim the tops with scissors to keep the onion seedlings around 3-inches high. This will help the trays from becoming top heavy and furnish more nutrients to the roots instead of the foliage. The trimmings can be added to soups, salads etc.
Transplanting Onion Seedlings to the Garden:
- To transplant, remove the seedlings carefully from the tray by squeezing the plastic gently, hold your hand over the seedlings, turn the tray upside down, and shake gently.
- Most times the root ball breaks apart when removed from the container. If the onions are more densely seeded, the roots will hold the soil together more firmly. Gently tease the onion seedlings apart for planting one at a time so the roots don’t dry out.
- Transplant the separated seedlings 3 to 4 inches apart depending on the variety. I use a fork or small tool to transplant onion seedlings. I pull the soil forward, place the onion seedling in the hole, and gently push back the soil. No patting or tamping in.
- Once seedlings are transplanted, water the bed gently. Onions have a shallow root system and need to be watered frequently to keep the soil evenly moist. Keep the bed weeded so the onions don’t have to compete for nutrients or resources.
If you are growing your onions to maturity, space them 6 inches apart and leave 6 inches between rows.
Onions require a high source of nitrogen, which will be important when growing in pots. Aggie Horticulture suggests this as a fertilization schedule:
“A nitrogen-based fertilizer (ammonium sulfate or ammonium nitrate) should be applied at the rate of one cup per twenty feet of row. The first application should be about three weeks after planting and then continue with applications every 2 to 3 weeks. Once the neck starts feeling soft do not apply any more fertilizer. This should occur approximately 4 weeks prior to harvest. Always water immediately after feeding and maintain moisture during the growing season. The closer to harvest the more water the onion will require…For organic gardeners a rich compost high in Nitrogen should be incorporated into the soil….While cultivating be careful not to damage the onion bulb. As the onion begins to bulb the soil around the bulb should be loose so the onion is free to expand. Do not move dirt on top of the onion since this will prevent the onion from forming its natural bulb.”