So, you've constructed your first hotbed and you've left it for a little while to settle down. Students look at you like your mad as you pull a bamboo cane from the ground and tell them to touch it. It's cold, you know it's cold, you know they will flinch a little from it, from the clay cold feeling of the cane. Then you repeat it, pulling the cane from the hotbed which steams a little when you pull off the lights. They touch the cane, it's a cold day, the cane is warm to the touch and then they realise they are touching the warmth from decaying manure and they flinch again but this is the beauty of hotbeds at play. This is what makes them contemporary for many gardeners and allotment holders who cannot afford or have a greenhouse due to bylaws. Who do not have electricity on the plot. Hotbeds are an old idea becoming very fashionable again if you have access to a lot of fresh manure and we do. Our manure is a mix of horse, pig, goat, sheep, rhea, alpaca and chickens. Our manure heaps at the Hopwood Garden are monstrous, agricultural monstrous, and the heat coming from the first bay, which is now full is wonderful to behold on a cold day. Now the experiment really begins, which method will allow a selection of seeds to grow fastest and fullest? Our seeds are lettuce, radish, spinach and spring onions. A little heat should get them going.
There are some unconventional tools in the sowing of a hotbed. Direct sowing involves making drills in the soil, or casting it in blocks but it always involves bending down, buttocks in the air, waddling along as the robins watch you. The hotbed version is a short plank to keep the drills straight and no bending over. It takes around twenty minutes to sow the hotbed, as each student takes a turn to learn how to sow seed thinly. We show them two techniques, (a) watering the drill before sowing, and; (b) watering it after sowing. We give them the pros and cons from cold soil to washing the seeds away. We show them how to pinch the compost back over the seeds, how to label and place the lights back on.
Then we have to repeat the experiment the modern way. This time there's pots, a water bath to show them how to water seeds in the pot from below rather than above - to avoid washing the seeds to the edges of the pot. There are some thickly sown pots, cries of the seeds being tiny or the seeds being too black to see on the soil. We label. We water. We place the pots in a propagator on a heated bench. For those of you who have never used a heated bench or heated propagator, it gives regular bottom heat making the soil warm and speeding up germination. The seedlings will have to remain on the bench, covered through all stages to avoid frost damage, same goes for the hotbed. Heated benches are used on a massive scale in the commercial growing sector and on a small scale in heated propagators on windowsills across the world. They give a constant heat to growing plants.
Now we wait. Which will win? The hotbed or the heated bench? Place your bets!