Gardeners can utilise coldframes to protect plants from the cooler temperatures of early autumn. Coldframes are distinct from mini-greenhouses as they are not heated and do not offer protection from ground temperature.
These structures are useful for safeguarding hardy seedlings and can be an alternative for those without a greenhouse or sufficient windowsill space. Seedlings placed in a sunny coldframe benefit from direct sunlight while being protected from animals and the worst of the chill.
Coldframes are suitable for growing hardy annuals such as poppies and cornflowers, and for starting sweet peas. They can also be used to house pelargonium cuttings until the weather becomes properly frosty, with bubble wrap suggested for additional thermal protection.
For those on a budget, an upturned large plastic tub can be an effective alternative to a flatpack coldframe with plastic panels.