One of the biggest reasons organic gardeners incorporate onions in their gardens is because they’re a high-yielding crop. In about 1 to 1 ½ feet of space, you can grow between 20 and 50 onions, which is ideal for those of us who enjoy adding them to our salads, do canning, and use them for cooking.
Onions can thrive in any section of the garden, so feel free to place them near slower or faster-growing vegetables. Onions can be grown several times in one season because they’re quick to grow and can be ready as quickly as 20 to 30 days after planting.
Here are some tips for starting your onion sets and harvesting them:
The difference between onion seeds, sets, and transplants
You can grow onions from seeds, sets, or transplants. If you opt to grow your onions from seeds, the entire process can take up to five months. Sets are young, small dormant bulbs grown from the previous year which makes them easier to plant than seeds or transplants.
Onion sets are generally easier to work with because they’re less susceptible to disease. They also mature in as little as two months or less. If you prefer to work with transplanted onions, plan on waiting two months for them to mature.
Bulbing versus bunching onions
What do you intend to do with your onions? Are you making salsa, canning them, or adding them to your fresh salads?
Bulb onions have a wide size range, so think about if you prefer the small pearls or large Spanish types. Bulbs can be white, yellow, or red at harvest time, so it’s important to know the specific variety or varieties you’re planting.
Bunching onions are usually grown by people who enjoy their green top stalks. They are also called scallions or green onions and are harvested before the bulbs completely form.
When to plant and harvest your onions
Onions are ideal for mid-spring planting in Iowa because their tops form in cool weather whereas their bulbs form in warm weather. Temperature and day length greatly influences the timing of bulbing.
If you’ve added onions to your organic garden, know that they will grow slowly if the temperature stays around 30 to 40 degrees for too long. If you’re located in southern Iowa, plant your onions in late March or early April for a May or June harvest.
If you’re living in central Iowa, plant your onions in early to mid-April In northern Iowa, onions can be planted mid to late April. Make sure to plant seeds in rows 12 to 15 inches apart so the roots have enough room to grow.
Use organic compost
Onions grow best in a pH of 6.0 to 7.5, so be sure to add compost to your garden bed before planting begins. Turn your well-aged compost, worm castings, or manure into the onion bed to prep the soil. Turn the soil at least 8 inches deep to ensure saturation.