Nothing, that is, except a lot of ingenuity and tender loving care. Gillespie has worked on perfecting his present greenhouse for about six years. He has developed so many good ideas that he now has a consulting business for building greenhouses and cold frames. An easy alternative While Gillespie has graduated to greenhouses himself, he believes in the value of cold frames for those who aren't ready to take the big plunge. A cold frame, he said, allows gardeners to start plants outside as early as March.
Cold frames can vary as much as their owners.
Frames can be either extremely simple, like stacked bales of hay or straw covered by an old windowpane, or more complex and permanent. They can be built with new materials or recycled ones. A very effective, but simple, cold frame can be constructed by hinging a window frame onto a south-facing outbuilding, then enclosing the sides. One advantage of a cold frame is that it's portable. The gardener can place the frame over a section of the garden until the danger of frost is past, then move it aside.