<P> This can be in the form of a clear enclosed bin sitting over a hotpad, or even a portable heater pointed at the bin . The key is to keep the moisture in the clear bin, while keeping lighting over the top of it, usually . </P> <P> An electric seed - propagation mat is a heated rubber mat covered by a metal cage which is used in gardening . The mats are made so that planters containing seedlings can be placed on top of the metal cage without the risk of starting a fire . In extreme cold, gardeners place a loose plastic cover over the planters / mats which creates a sort of miniature greenhouse . The constant and predictable heat allows people to garden in the winter months when the weather is generally too cold for seedlings to survive naturally . When combined with a lighting system, many plants can be grown indoors using these mats . </P>

Examples of plant species that are propagated by the methods