While a greenhouse will stay warm during the day, the temperature will drop at night. How much it drops depends on what material you put in it to keep it warm. Having a thermostat in the greenhouse will help you know when you need to start warming it up.
Here is a list of ideas to help keep your greenhouse warm.
- Insulate using bubble wrap
- Water in plastic containers – (this is where hydroponics and aquaponics come to mind…)
- Use horticultural fleece
- Invest in a heating system
- Space heaters
Here is a video with more ideas from Living The Good Life on You Tube.