I must admit I hate the heat

I love the sunshine but humidity really knocks me flat. I bought all my seedlings on Sunday when it was baking hot so was very relieved to see rain in the evening. I am a complete & utter beginner so I am keeping a watchful eye of my little stash. I'm frightened of over watering them especially as I've planted some in those self watering pots that have a little reservoir in the bottom & I've used that moisture control compost that is supposed to cut back on watering. They are in one of those plastic greenhouses at the mo so I'm praying they'll fare well.