Victory Gardening Series: How to Grow Onions

By Dawn Gerlica, HF&G Horticulturist

In our Victory Gardening series, we explore how to plant your own vegetable garden during these uncertain times. This week, we are exploring the delicious world of onions, for all of those home-cooked meals yet to be made!

It’s time to plant onions. Most onions need a longer growing season than we have in northeast Ohio so they either need to be started from seed in February or grown from last year’s small bulbs, called onion sets. Don’t fret if you’re just finding this out now – there are still things to do.  

One onion bundle spread out

If your local garden center or hardware store still have them in stock, you can purchase onion sets. Sets are usually limited in variety to white, yellow or red and sometimes sweet, but they mature early, and they are easy to plant. They also sell out quickly.  

The garden center may also have started onion plants. Nurseries often start large batches of the seeds early and now that it is time to plant, they pull them up, bundle them and send them out to growers and garden centers. These are still very easy to plant, and you can get a few more varieties to fit your requirements. A few different things to consider in the different varieties are sweet, hot, small bulbs, large bulbs, long-storing and short-storing, along with the different colors: red, white, or yellow. 

Adding compost to the soil ahead of time where the onions will be planted is a good idea. Onions like loose, nutrient-rich soil and don’t want to have their roots disturbed later. But, be aware most root crops need less nitrogen than other crops because the primary growth is being put into the roots. Nitrogen helps the leaves, but phosphorus and potassium are primary nutrients for root growth and general health.  

Onion sets

Once you have onion starts or sets, they should be planted about 2 inches deep and 6 inches apart in prepared garden soils. Planting too deep may cause them to rot before they grow and a hole too shallow may not keep the plants stable in the wind, damaging the roots.  Furrows are often suggested for onion starts because care should be taken to get all roots covered. If you put started onions in a hole, sometimes the roots are long enough to end up caught on the edges and pointing skyward or sticking out of the hole which should be avoided. Push soil back to fill in the hole around the bulb and make sure the plants are standing up. Within a few weeks there should be new growth and the onions will be on their way. 

Onions do not like to dry out during the growing season, so it is a good idea to mulch them with something like straw once they start growing and the soil has warmed. If the weather gets too dry, water once a week. When the tops turn yellow, pull back a bit of soil to expose the bulb top to harden. This will prevent rot in storage. A few days later, the bulbs can be pulled and dried for a few weeks before storage.  

Planted onion start