Easy-to-grow onions are a gateway to veggie gardening

Question: My New Year’s resolution is to grow my own vegetables this year, but I don’t know where to begin. Do you have any suggestions?

Answer: One of the great things about vegetable gardening is that you can start small and expand. Short on outdoor space? Start with a small patch of earth or just a container or two. Don’t have a lot of knowledge or experience? Learn by starting with something easy and fun to watch as it comes to life. Money a little tight? Grow something you regularly buy at the grocery store — you could come out ahead!

One small vegetable that can be rewarding in a big way is the onion. Onions require little care, can be grown in small or large spaces and provide a sprightly flash of green in the garden plot or pot. They are also loaded with nutrients and very versatile, playing a major role in cuisines throughout the world, and loaded with nutrients. Onions and related species of the genus allium (garlic, scallions, leeks, shallots and chives) have been cultivated for more than 5,000 years.

Green onions, also called bunching onions or scallions, mature in as little as 30 days when planted as seedlings. The big yellow, red and white varieties, on the other hand, can require 100 days or more to grow to large size, if started from seed. An advantage of all alliums is that they can be harvested at any stage of growth. Their leaves, when cooked, can be as tasty as the bulbs.

This month is the perfect time to plant onions in Sonoma County because cool weather during the early growth stages yields the highest-quality bulbs.

You can grow onions from seed or from seedlings (“starts”) purchased at a nursery. Sets are also available, which are dried young bulbs often sold in net bags. However, many gardeners find onions grown from sets are likely to bolt, or go to seed, before they reach full size.

You may hear of long-day and short-day varieties of onions, a distinction that refers to their growth habits at latitudes with longer or shorter periods of daylight. Like so many things about Sonoma County that are “just right,” intermediate-day types perform best here in our mild weather.

Most onions need lots of sun and well-drained, compost-enriched soil. They do not like areas with rocks or dense clay.

Many onions have very specific requirements. As always, consult the seed packet for variations such as optimal planting time and days to harvest.

Onions like moist (not wet) soil. As soon as you see them emerge from the ground, weed carefully so you don’t disturb the baby plants and mulch to retain moisture, using straw or other organic materials such as dried leaves or wood chips. A good high-nitrogen organic fertilizer will give you the largest bulbs, but don’t overdo it — too much and you risk double or split bulbs.

In general, if you’re planting green onion seeds, you can plant them quite close together, then thin them with scissors (use the greens as you would chives) to 2 inches apart. Start larger varieties indoors or buy starts from a nursery, then move them to the garden and plant them 6 inches apart when the ground temperature hits 50 degrees.

Pests aren’t usually a big problem for onions in Sonoma County. A great resource for all garden pest problems is the University of California’s Statewide Integrated Pest Management Program website. There is a whole page on onions and garlic at bit.ly/3EFqJLw.

One week before harvesting onions, stop watering. Onions are ready to harvest when the stalks fall over and start to look dry and yellow and the bulbs start to push their way out of the soil.

Dig your onions out carefully and let them dry outside for a few days, away from direct sun and with good air circulation. Then brush off the soil, trim the stem to 1 or 2 inches and store in a cool, dry place. You can store them on flat trays or in mesh bags, but keep them away from other fruit and vegetables that might give off ripening ethylene gas.

Contributors to this week’s column were Charles Desmarais, Sue Lovelace, Ellie Samuel, Diane Judd and Joy Lanzendorfer. The UC Master Gardener Program of Sonoma County, sonomamg.ucanr.edu, provides environmentally sustainable, science-based horticultural information to Sonoma County home gardeners. Send your gardening questions to scmgpd@gmail.com. You will receive answers to your questions either in this newspaper or from our Information Desk. You can contact the Information Desk directly at 707-565-2608 or mgsonoma@ucanr.edu.