Growing In An Unheated Greenhouse

This is an excerpt from 'Greenhouse Growing and Construction: How We Do It.

If a deep freeze is forecast, then a plastic sheet or cover can be put over the plantings in the greenhouse for extra protection.  We also use plastic coverings in the fall for some plants when night time temperatures fall below 25 degrees or so regularly.

We left a plastic cover over some spinach plants in our unheated greenhouse.  With protection of the greenhouse, and  the added protection of the plastic cover inside, these spinach plants were able to survive an outside temperature of 22 degrees below zero last Wednesday February 5th.

Spinach survived 22 below zero.