Why Warm Your Soil?
Plants react adversely when either the air or soil temperature drops below certain levels. However, with a warm soil plants will be much more capable of standing low air temperatures.

For this reason, the use of soil warming equipment is both productive and economical in a greenhouse. It will allow your plants to get off to an early start and will maintain even temperatures which help to avoid and checks to growth.

The use of soil warming equipment is frequently used by amateur gardeners attempting to grow prize-winning huge vegetables. If they use it, you can be sure it is of great use.

SOIL WARMING CABLES - COMMON METHODS

There are two main methods of warming the soil in your greenhouse. The first, rarely used because of the complexity and expense is water pipes laid under the soil which have pumps to circulate warm water round them. This is not a method we would advise for most gardeners.

A much more common method of soil warming is the use of plastic propagating trays which have soil warming cables in their base connected to the standard electricity supply. Normally a thermostat is also built-in to enable the temperature to be varied at will and kept constant.

The application of heat to soil makes very little difference to the surrounding air temperature but it does allow the greenhouse to kept at a lower temperature with no adverse affect on your plants. This really does reduce considerably the cost of using a greenhouse in the colder months.

Ready made units are widely available which incorporate cables and a built in thermostat,  some  also have a clear perspex cover to retain heat but allow light to reach the plants. Our recommended supplier for propagating kits is Harrod Horticultural. They produce top quality equipment at good prices. Click here to view some of their products.

SOIL WARMING CABLES - BUILD YOUR OWN UNIT

It is also entirely possible to build your own propagator to fit the exact space available to you. If you wish to do this follow the instructions below.

Buy good quality equipment and be sure to follow all the manufacturers instructions - electricity and moist soil only go together when the correct procedures are followed and good equipment is used.

Make a wooden frame with sides which are about 4" (10cm) high with a base (like a drawer). You may wish to protect the wood from water damage by covering the base and inner sides with plastic sheeting.

Put a piece of 1" polystyrene covered polythene in the base, lay the soil warming cables on it and cover with approx: 1.5" (3/4cm)of coarse sand. The cables will need to be connected to the electric supply as recommended by the manufacturer. The pots or trays are then simply placed on the sand which will warm them.

To get the best use out of this equipment, connect up a thermostat to the soil warming electric cables as per the instructions and you will have the perfect environment for your plants in the greenhouse. Click here if you wish to buy soil warming cables online from our recommended suppliers.

 

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