best product to use for insulation in greenhouse

I am looking into purchasing a greenhouse and was looking at different types of insulation. as u would expect a lot of pros and cons for each one. so was hoping someone could tell me from experience what they use and how good it works.

 

Welcome to Gardeners Corner

I think @Tropical_Gaz mentioned the other day that it's cheaper to provide artificial light & heat in a building than it is to heat and light a greenhouse over winter.

 

Greenhouses tend to have lots of gaps and drafts, plus hort glass (or safety) is pretty poor at insulating. we do use bubble wrap on the 2 greenhouses we have but it takes a lot of energy to keep them warm.

We also have an insulated outbuilding - wooden built, plastered internal walls with insulation in the roof and walls. We provide just a small amount of heat over night on the colder days and have used a grow light on a timer. This is a much lower use of electricity and so costs a lot less. However if you had to build the outbuilding first then a greenhouse is still going to be cheaper.

But if you have the choice use somewhere with better insulation - a cellar, insulated shed even a garage and dont worry about it being dark but use growlights.

If you can provide natural light on warmer days - eg open a shed/garage door then thats even better.

Our shed does have windows and the plants get some natural light as well but its not what you would call bright.

Clearly you need to consider the plants you over winter this way as some are more accustomed to gloomy conditions. Anything that needs a lot of light would be better somewhere else. But by planning ahead you dont have to spend a fortune heating a greenhouse!

 

With the greenhouses, we do provide some heat, but work on frost free, rather than keeping "warm". on the darker sides and at the bottom we use offcuts of kingspan foam insulation and then big-bubble bubble-wrap.

Use a heater with a thermostat and manually turn it off when you know temps will be ok.