I have a small greenhouse and I like to grow my own onion plants, they always seem to do better than sets and the mature bulbs seem to keep longer in storage.

My problem is, my plants are always spindly in the greenhouse and when I transplant them to my garden, it’s like trying to plant blades of grass. I can’t seem to grow my plants stout and vigorously in my greenhouse, like the plants that I could order from the seed catalogs. I know those plants are field grown in the south and their hardiness is easily created by that method, but I was wondering if any of you have any experience with growing your own onion plants and getting stout and hardy plants.

Once my plants are in the garden, they do well and produce nicely, but I’d like to grow better plants for transplanting.

I keep the tops trimmed to a few inches tall, and this year I’m trying them sowed in deeper pots to allow for better depth for the roots. I’m also keeping the temperature low to about 50 degrees nighttime and around 70 degrees daytime. My plants are about two weeks old at present.

Is there a solution or other trick I could employ to ensure stouter hardier plants?

Sunlight in greenhouses are less than those in open fields. I think onions need full sunlight in open fields, not the partial shade in green houses. Maybe you should have them grown in pots outside the greenhouse.

It may be that your plants are not getting enough of the proper wavelengths of light. If you are in North America, it is winter still and the angle of incident radiation does block out certain wavelengths. Anyway, the solution is a grow light. I bought one for about 20 dollars at a local gardening place called Dig This.