We propagate large amounts of vegetable seedlings in the early spring so need some heat to get them going. Clearly a heated propagator or heat mat isn't really practical as we need such a large area so we use soil warming cables buried in sand to provide the warmth we need for germination. There's a little bit of work in setting up the bench but once it's in place it's simple to use and should last you for years. What's the plan? The idea here is to embed the cable evenly in a box of sand covering the area you want to heat, it's a bit like an electric blanket but sand instead of a blanket. We need to build a box at a convenient height strong enough to hold a decent quantity of damp sand and all your seed trays. Here's the list of stuff your need:
- A base for your bench. Old pallets or crates are handy.
- Sharp builders sand available from your builders merchant.
- Foam insulation board.
- Heavy gauge waterproof polythene.
- 6 inch high planks for the sides
- Timber board for base
- Corner posts
- Screws or nails to hold it all together.