Hello everyone! I've been a full time gardener for around 8-9 years now & I feel like I grow nice produce...once it's in the ground! Now on my 4th or 5th of having a greenhouse but I feel like my greenhouse growing skills are subpar at the most. I use new or disinfected pots/trays, use professional growing mediums, use warm water, water when plants look like they need it or when trays are light, use compost tea to fertilize after 3 weeks, good circulation, but my plants are always pretty sad looking :(. The only thing I can think of that is my problem is the temperature extremes; ~40-100. What do you think? Thank you

Welcome to NGA, @Savitskyfarm .

It certainly sounds like you're putting plenty of effort into growing your plants! How large is your greenhouse? What kind of plants are you growing? Do you have any photos of the problems the plants are exhibiting?

Greenhouse is approx. 12x18, arch shaped, north side against garage. - these cabbage are almost a month old. They look a week old to me?

Remember, cabbage is a "cool" weather crop. Cheers!

Very true that all the brassicas are cool-weather crops; but those little cabbage seedlings look nice and healthy to me -- mine normally take a while to get going, although I couldn't really specify a timeline for them. If yours are in regular seed-starting mix they might benefit from a little (weak) fertilizer at this point.

Part of the problem is definitely your temperature swings. 40-100 are hurting your plants. As far as your cold weather vegetables, 40 at night is fine, but no more than 60 during the day.

Are you venting your greenhouse during the day? Doesn't sound like it if the temps are reaching 100. Where are you located?

What are you using for growing medium?