There are steel greenhouses as well as plastic, aluminium and wood. My recommendation would be for one of the latter two, they are both excellent but each one have different merits. I find the wooden ones, particularly if made from cedar wood, to have a very warm feel about them whilst the aluminium types will never need any maintenance on them.
Home - Greenhouses – Types, Suitability, Cleaning, Heating and Lighting
Medwyn Williams
Hello. I'm Medwyn Williams – eleven times Gold medal winner at the Chelsea Flower Show, Past Chairman of the Royal Horticultural Society Fruit Vegetable and Herb Committee and President of the National Vegetable Society.