Fall and Winter Care of Onions

Q. My onions are up from seed I planted in September and doing great. I planted Candy and Texas Super Sweet. Both are sweet onions. What should I do now?

Nevada has a great climate for onions, both northern types like this long day Walla Walla grown in Las Vegas, short day like Texas Super Sweet or in between. Spend a little bit more and get some good sweet onions instead of traditional types.

Texas Super Sweet, a short dqy onion that grows well (and tastes great) in Las Vegas

Or this intermediate day onion, Candy

A. Onions are planted from seed in the fall. September is good timing. Planting them too early in July or August can cause too much top growth and flowering. The trick is finding that happy balance between late summer warm weather and cool fall weather. Mid to late September and early October are usually good months for that in our climate. Watch local weather to make your final decisions.

Onions can be planted from seed in the fall or transplants an sets in the spring.

            Onions seedlings, now called transplants, are dug up around 1 March and replanted at their correct spacing for bulb development. I broadcast the seed in the fall so the seed is very close together. I don’t care about spacing or bulb development at that age. I just want seedlings up high enough, 6 to 8 inches tall, so I can space them out in the spring 4 inches apart. If I am shooting for jumbo size, I will plant them 6 inches apart.

            If your seedlings are already about 6 inches tall then I would not fertilize them anymore. However, if they are still small I would broadcast a high nitrogen fertilizer like 21–0–0 or blood meal (12-0-0) and water it in. This shot of nitrogen fertilizer will give it a last push of new growth before it gets cold this winter and they stop growing.

            In late February or early March, dig up the seedlings, careful not to damage the roots, and replant them into rows or blocks depending on your gardening method. Always replant using a starter fertilizer such as 16-20-0 or a fertilizer with a similar nitrogen to phosphorus (16/20) ratio. Fertilize onion seedlings once a month, lightly, with a nitrogen fertilizer or a foliar nitrogen fertilizer.