Greenhouse and Orangery size ought to depend on the amount of available space in your garden. If you only want to grow a limited amount of crops, so you may be able to compromise. But if you have more ambition or if you are a couple who want to work or reside in the house you should strongly consider getting a bigger house.
Juliana range in greenhouses and orange pieces ranging from 0.85 m2 for basic growth of crops such as cucumbers and tomatoes and up to 72 m2 where the sky and your imagination is the only limit.
Choosing a polygonal house will allow for a garden table to stand in the middle and plants along the sides. In these cases you can settle for about 7 m2.