Far from being the ultimate new central heating fuel, what I’m suggesting is something last used by Victorian head gardeners: a hotbed. You can use it as an eco-friendly heated propagator for raising seedlings or as underfloor heating for “forcing” early veg and best of all it’s free.
First find your manure. Horse is best. What you want is the freshest you can get. It must not be well rotted.
Now you need a cold frame and a sheltered sunny spot with welldrained soil. Dig a hole 6in deep and about 1ft larger all round than the floor area of your cold frame. Spread a little gritty sand in the base for drainage then sort the straw from the pure manure and pile it into the hole so it makes a rectangular heap about 2ft high, with slightly sloping sides.
Press it well down all over with a spade, like a big mud pie, so the whole thing stays firm.
Pile the strawy stuff over the outside for insulation, give it a final firming and sit your cold frame squarely on top. Then spread a 6in layer of good topsoil or potting compost inside the frame and close the lid.
If you happen to have a greenhouse or a walk-in polytunnel, make a hotbed inside that on top of the soil border but there’s no need to use a cold frame since the structure itself acts as a cover.
Leave your bed of manure to sit and stew for two weeks. It should start to heat up. You’ll know by the steam. Now you need a soil thermometer. Stick it in to the hotbed in several places so you have a good idea of average temperatures inside and check it every few days.
To start with the heat builds up fast then it slowly drops and when it gets down to 75F (24C), a week or so later, you can start sowing seeds in the compost.
Victorian gardeners used their hotbeds to raise young vegetable plants and sow salads, leeks and early brassicas from late February to give them an early start.
They also sowed half-hardy veg such as French beans, courgettes and bedding plants in March, though today I’d play safe and raise those on warm windowsills indoors and then plant early veg plants or stand trays of bedding on your hotbed to grow when the outdoor weather has improved.
The free underfloor heating generated by the manure warms the roots in just the same way as an electric propagator and keeps the contents of the frame several degrees warmer than the outside air, then as the manure breaks down plants have all that natural nourishment to tap into.
Can I see you shaking your head at all the effort needed to save a few bob? Ah, but what price feeling virtuous?
FLOWER POWER FOR A COLD CONSERVATORY
IF YOU don’t heat your conservatory you might be forgiven for thinking you have to miss out on all the spectacular flowers that people who’ve taken a more Kew Gardens approach will be enjoying at this time of year.
But you can still have some out-of-season colour and glamour if you bring in certain “star” hardy plants grown in pots.
They’ll flower far earlier than usual and what’s more you’ll enjoy them close to and in perfect condition since under cover delicate blooms are kept safe from wind and rain.
The first to flower right now is florist’s mimosa (Acacia dealbata). Its fine ferny foliage makes this a most attractive tree for a tub on the patio for the rest of the year but brought inside now it’ll soon be a mass of fluffy yellow balls of bloom and the fragrance is wonderful.
Growing it in a pot helps to curb its large size by acting as a “corset” on the roots but you can also prune it after flowering to keep it small. The camellia makes another attractive shrub to enjoy indoors but it pays to bring it in now before the buds are too big, since a change of ambient conditions once they’ve formed fully can stress the plant and result in bud drop.
Keep the temperature and moisture level in the compost as steady as you can for the same reason. But with a little care you should see your plant in full flower weeks earlier than it would be outdoors.
The other big star to bring into the conservatory is tree peony. Again, they’ll flower weeks earlier than usual in the warmth and the fragile flowers are incredibly showy.
And if you have pans of spring bulbs coming on in a cold frame, greenhouse or a sheltered place outdoors, bring those into an unheated conservatory as soon as the buds start to show their first hint of colour and stand them up on a table.
You’ll see them at their very best, giving a brilliant display.
For more information on gardening and other subjects go to Alan Titchmarsh’s website: www.alantitchmarsh.com