I'm envious! I'd love a little greenhouse! What is the nighttime temp in the greenhouse? Seeds are sensitive to soil temperature, e.g. peppers like it hot, about 80 F or higher. They will not germinate if the soil is too cold, so they are probably waiting for warmer weather.

Don't go just by air temps during the day. You can measure the nighttime temps by getting a min/max thermometer.

Also, have you tried starting the seeds in the house and then moving them to the greenhouse?

It's about 90-100 outside. I have a thermometer inside, night time temps were anywhere from 86-72. It would be around 84 in the greenhouse. I know my dad has gobs of luck inside his house! He has an abundance of vegetables! This year I've been saving my coffee and tea grounds (caffeinated) I wonder if that would help?

What was the temperature/ month when you started the seeds? Peppers are a warm season crop, while onions and cilantro like cooler weather and can be planted even in the fall for spring harvest.

How did you fertilize your plants?

Coffee and tea grounds will not help -- if you are growing plants in containers, they need to be fertilized properly. You can buy organic fertilizer (like fish/kelp emulsion) or use synthetic ferts (like Miracle Grow for Vegetables and Herbs).

It was last year's temps. Mid July in Southern Kentucky. This is my first time lol I just use the miracle grow with fertilizer already in it.

I suggest you start with something easy this spring, like annual flowers: zinnia, marigold, nasturtium, sweet alyssum, etc. Basil also works great!

Plant the seeds when nighttime temps inside the greenhouse stay above 60F. Follow the instructions on the seed packets. Planting depth matters. Do not overwater (always check if the potting mix is getting dry). Start fertilizing with diluted fish emulsion when the second set of leaves starts to emerge (again, follow the instructions on the bottle).

Check here with us along the way, and let us know how you're doing!

This exercise will give you some confidence and prepare you for starting cool season plans in the fall (like chives, lettuce, arugula, Swiss chard, parsley).

One thing that strikes me in your OP is that the thing that grew was sunflowers, which have a much larger seed than most of the others. Is it possible that you planted the smaller seeds as deep as sunflower seeds, so they were not able to reach the surface before running out of stored energy and material? Seeds should be planted only about 2 or 3 times their own diameter deep.

If your nighttime temps are 86-72 with the inside at 84.... what are the daytime temps inside if its 90-100 degrees out? While that 70's-80's degree range can be great for seed starting, once you get up around 90+ you are starting to cook the seeds.

You don't say what the framing or glazing material is, but it sounds like you could use a ventilation system. You should be able to retrofit these into just about any greenhouse. You put an exhaust fan up high in one gable end, a motorized intake shutter down low in the opposite end, and wire them both to the same thermostat. The fan and shutter will open at the same time allowing fresh air to flow through the greenhouse cooling it. If you don't have electricity there are solar systems available. Here is a short 1 minute video showing how to place these components. For your size greenhouse you would need a 12" exhaust fan with one 12" intake shutter. Tammy

https://youtu.be/etp9aqtPPac

Thank you so much @Advance Greenhouses ! My greenhouse is like a polycarbon I think. I'll try to post a picture of it!

Meanwhile here it is! Except my dementions are different!

https://www.harborfreight.com/6-ft-x-8-ft-greenhouse-47712.html?cid=paid_google|PLA+-+Top+SKUs+-+All+%28Main%29||47712&utm_source=google&utm_medium=cpc&utm_campaign=PLA+-+Top+SKUs+-+All+%28Main%29&utm_content=&gclid=Cj0KCQiA7NKBBhDBARIsAHbXCB5A75Jk1nTyKPFaoea1asnd49lB35Dm5X2wCHhmRHq3s5zPJYQQb2EaAlxxEALw_wcB

i would never use a media with fert in it for seed starter.. and i would never use it otherwise ...either ...

We have a similar greenhouse. I had thought I was going to use it for seed starting, but after a couple of years we have switched course.

Our son did a science experiment two years ago. He thought he was going to prove how much better the seedings we grew in the greenhouse were, but he ended up proving the opposite. In every measurable way, the control group (grown at the same time with the same medium on our uncovered patio table), out performed seeds started in the greenhouse. I think they were getting too hot and we were cooking them.

We are now in the process of adding large raised beds inside the greenhouse. We will use them for peppers, tomato, pineapple and ginger. We hope to grow these year round and they need more warmth than we could give them without the greenhouse. Our door will stay open 11 months of the year to add to the airflow and keep them from getting too hot. I am hopeful, we can turn this back into a productive space.

I suspect you are having a similar issue with your greenhouse getting too hot.

I appreciate everyone's input!

Now about seeds?

We had a nice thaw here over the past couple of days, and I'm looking forward to buying some seeds. Their relavitly cheap here, and I have a ton of flower seeds that I planted around my koi pond last year. What kind of seeds would yall recommend me getting? I think we might be having a false spring (Im in Russellville KY.) Zone 5 I believe, we're right on the line with Clarksville Tennessee, and I think their zone 5/6) I have those little plastic carts that restaurants use to haul dishes around in. My sister can grow anything! She can literally throw seeds outside her door and she's got an abundance of vegetables and flowers! Of course she has chickens that fertilize her yard!