Plant Onion Seed Now

Q. I would like to grow both yellow and red onions. When is the best time to plant them?

A. Onions for bulbs or green onions can be planted from seed mid-September through November in our latitude and elevation. Onions produced from sets or transplants should be started in March. They can be grown in a garden spot or 5 gallon containers. Onion sets, which are small onion bulbs, are

Contessa onion

easier to plant than transplants and usually have a higher success rate for most home gardeners.

Let’s focus on fall planting using onion seed. Growing onion from seed to produce green onions or transplants does not require very much space. Seeds can be spaced close together so I broadcast the seed, or sprinkle them, in the area where I want them to grow. The seed can be as close as ½ inch apart and even closer for green or bunching onions or even transplants.

For green onions just about any onion will do so shop for inexpensive seed. If you are growing transplants from seed then be more careful in your selection. I prefer sweet or specialty onions for transplants that I am growing into bulbs.

Big Daddy Onion

Las Vegas is in a transition zone so we can grow short day, long day and intermediate day varieties. These include the northern varieties like Walla Walla or southern varieties such as Vidalia. They just mature at different times. Varieties such as Candy, Big Daddy, Vidalia, Walla Walla, Yellow Granex, Bermuda, Texas Super Sweet, Contessa, Sterling, Red Marble and specialty onions like Cipollini, and Red Longa always do well in our climate and latitude.

Red candy apple Onion

Before planting the seed prepare the soil to a depth of 12 inches. Sandy soils that drain well are the best. We are not yet focusing on growing the bulb so any high nitrogen fertilizer will work well. You won’t need to fertilize them until after the seed is germinated. When you’re done mixing all the compost into the soil, make sure the soil is not “fluffy” so pack, roll or compress the soil lightly to make a firm seed bed.

Onions for transplanting, green onions or bunching onions grow well in containers or in blocks. They do not need to be planted in rows at this time. Carefully scatter the seed on top of the soil and cover the seed with about ¼ inch of topdressing or lightly rake the seed into the soil and add a light surface mulch.

Red Tropea Longa

Water the top dressed are mulched area twice a day until you see germination. Fertilize them after you see them begin to emerge. You can lightly broadcast a high nitrogen fertilizer on top of the mulch or topdressing and water it in. When you see germination reduce your watering to once a day. If onions are too close together, harvest and use some of them in a salad or stirfry to give them some space. As temperatures cool down and the plants get larger you will be able to water every other day and even every third day as it enters the winter. You will get larger transplants if you fertilize a second time with a nitrogen fertilizer about one month after the first one. Leave them in the soil all winter long. Dig up transplants in March or continue to use them as green onions.