Willeke,
You will find it much "safer" if you want to call it that, to keep them inside the greenhouse.
You have a door that can stay open allowing air flow for both circulation and reducing heat if it should get too hot inside it. This should not be the case.
If you do not have a large number and can put them out on a bench of sorts outside of greenhouse if you will be there to move in out of rain. This is what I do with some of mine.
I prefer to manage any water my trees get, whether it straight water or fertilizer mix. This way I do not miss any watering with fertilizer during growing season. I mist my trees on hot days in the A.M., then the water has evaporated before days hot sun is upon them.
The misting helps to also create a less desirable environment for mites.
I have juice jugs painted shiny black. Fill them with water and let the days hot sun heat them. This helps to keep night temps. higher. Works like a charm.
Your brick wall behind greenhouse will definitely help with added warmth at night.
