Don't know what went wrong. I always have the opposite results. Try to get seedlings into greenhouse as soon as possible as I get much better growth with natural sunlight. Is your greenhouse shaded? I use no additional lights in greenhouse. What temp is your greenhouse at night?

Marv-Montezuma, IA

Here is a link that might be useful: Photo Albums

i keep it about 52 f at night,and during the day the sun warmed it to at least 80F (this was in winter).

Did you use the same brand of potting soil?

I bought cheap potting soil once. Turned out to be acidic. Plants that did grow grew very slowly.

And I know it was the soil as my local greenhouse owner had started the plants for me. And her plants were twice as tall.

If you are growing annuals, the night temp is low for seedlings.

I tried winter sowing this year in my unheated greenhouse, and my plants are definitely smaller, but the last 2 days it has warmed up and they seem to be growing now. THey say they will catch up eventually.

Sterling