Cultivating onions from seed packets

By Gregg Eyestone

While inventorying seed packages, I found quite a few lettuce and radish left-over seeds. One way to see if they are viable is to sprout some in a wet paper towel placed in a closed plastic bag.

I decided to just plant them and see how it turns out.

The seeds were planted in a container with potting media indoors.

If they come up, I will grow them in our sunroom.

Onions are the first vegetable crop that can be started indoors from seed to be planted later in the garden.

Planting them now will get them off towards producing a good sized onion when harvested. Direct sowing of seeds in April produces only small onions.

Purchasing onion plants is another option for getting large sized onions.

I find using a tray filled with loose seedling mix best.

A whip topping container with a hole in the bottom is one tray example. Vermiculite and seeding mix are equally mixed for the growing media.

The onion seeds are planted and watered. Plastic wrap is draped over the traay to hold in moisture until they sprout.

Seeds sprout best with warm temperatures. I use a germination mat but any location that is warm will aid in germination. By warming up the growing media, you get more seeds to sprout.

They will all sprout at the same time and the process is sped up. Onions and many seeds prefer the media temperature to be around 75 degrees.

Light and the right growing temperature will make short, stocky, and healthy young plants.

A florescent shop light placed right on top of the leaves will provide sufficient light and I leave the lights on continuously.

The growing temperature is normally lower than the germination temperature.

Since onions grow best outside with the temperatures of spring, I try to keep my indoor temperature in the low 60s.

One of the best experiences of starting onions from seed is trimming the tops. It might make you cry but in a good way.

Encourage stockiness by trimming the ends of the leaves when the plants reach 4 to 5 inches tall. Give your onions some light applications of fertilizer for leaf growth.

Start hardening off the onions in early March by moving the plants to a protected outdoor location. There’s a possibility that you may have to move them inside temporarily to protect them from extreme cold snaps.

Keep your onions frequently watered and fertilized in the garden to get the biggest onion harvest this summer.

Readers can find out more information on this and other horticulture topics by going to the K-State Research and Extension website at

You can contact Gregg Eyestone at the Riley County office of K-State Research and Extension.

Gregg may be contacted by calling (785) 537-6350 or stopping by 110 Courthouse Plaza in Manhattan or you can e-mail him at

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