Cold frames (low) and mini-greenhouses (tall) are used to raise, grow on and harden off plants from seed or cuttings. They're useful on their own, or as overflow space for the greenhouse during spring.

Traditional cold frames are permanent structures of brick with a removable glass cover (referred to as a light) - you can see these in traditional kitchen gardens of stately homes.

Modern versions come in all sorts of shapes, sizes and materials, with plastic or twin-walled polycarbonate replacing the glass, and tall narrow versions that fit in smaller spaces to grow taller plants where there's not the space or budget for a greenhouse.

But be warned - we were surprised at how hot they can become on a sunny day, even in February, so someone needs to be around to adjust the ventilation during the day unless you can fit automatic openers, which are only suitable for rigid structures. Automatic irrigation is an option for most designs, and heating too, which opens up a whole range of growing possibilities.