Agree. Fungus gnats are a symptom of over-watering, overly wet potting mix, and easily eliminated. Rather than Saran wrap simple curtain pieces cut from one of the inexpensive rolls of the clear plastic sold for a few dollars as painter drop cloths works fine. Plus they can be easily tied open to prevent over-heating and allow for the needed air circulation. As jack said, a 50 degree sunny day will result in temps of 90-100+ inside a sealed plastic unit and quickly cook the seedlings to death.

As long as they don't freeze, seedling will tolerate cool temps much better than hot ones.

Dave

Thank you both very much for your input. I will try the clear plastic, which actually will make it much easier to access the shelves. Now I'm wondering if I should use my thermostat to power a fan instead of a heater and circulate cool air if it gets above 75 in there.

" Now I'm wondering if I should use my thermostat to power a fan instead of a heater and circulate cool air if it gets above 75 in there."

Very likely although often it is enough just to open up the plastic so a breeze can move through. If the heat is trapped inside then all a fan will do it circulate the over-heated air, it won;t lower the temp.

Dave

So based on the advice I received here I decided to use clear plastic from 55 gallon trash bags cut in half draped around the cart instead of saran wrap. I placed the cart outside one day and the temp quickly started to rise above 78, so I decided to keep the whole thing in the garage instead of putting it outside.

To control temperature, I purchased a Inkbird Itc-308 temperature controller which I hooked up to a small space heater inside the cart. Turns on at 68, turns off at 72, that has worked very well thus far. Also have 3 48" shop lights providing light. So far so good.

My tomatoes have germinated about a week ago and the first real leaves are starting to now grow. Is it time to give them fertilizer? They are growing in mostly peat moss so I can't imagine there's much nutrients for them. I have on hand:

• Urea 46-0-0
• Ammonium sulfate 21-0-0
• Triple super phosphate 0-45-0
• Potassium sulfate 0-0-60
• Ferrous sulphate
• Magnesium sulfate

What should I give them and how much?

No need to feed until they develop their second set of leaves and when you do use something liquid and well diluted in their water to no more than 1/2 strength (1/4 strength is normal recommendation). Rather than fertilizers, everything you have on your list is far too strong to use on young seedlings plus they are all soil amendments intended to be mixed in well into a lot of garden soils.

Urea and ammonium sulfate are extremely strong sources of nitrogen and can easily kill even well established plants if used at full strength. Tomato fertilizers run in the range of 3-2-2 NPK or less so most any of those listed would have to be diluted down to about 1/32 or less in strength. Instead look for one of the many water soluble fully balanced plant fertilizer mixes that can be well diluted in water.

Dave