Winter sowing
Tomatoes and peppers, both sweet
and chilli ones, need a long growing season to produce ripe fruit and a
temperature of between 15 and 20° C to germinate. This means sowing them
in a seed tray (space the seeds widely, sowing twice as many seeds as
you’ll finally need) and growing them with artificial heat to maintain
the correct temperature night and day. Start sowing from the middle of
February.
If you have a greenhouse with an electricity supply an electric
propagator is the simplest solution. It will have a thermostat to keep
it at the temperature you select and your tomatoes or peppers will get
off to a good start.
Their cotyledon leaves are elliptical, with a distinct point and a
groove down the middle, the true leaves look like miniature versions of
the big plant. When they have four true leaves you will have to get them
out of the seed tray and pot them on and that is where the problems
start. It will still be cold and they will still need heat, but your
propagator will be jammed with deserving cases. Unless your greenhouse
is heated they will suffer when there is a hard frost, tomato leaves
take on a purple tinge to let you know they are struggling.
Put a layer of bubble wrap on the bench or staging and put on it a deep
tray (baker’s tray type) filled with earth or sand. Set the pots with
the baby tomato and pepper plants on this and have a cloche of more
bubble wrap to put over them at night. It really does need to be taken
off during the day as they need lots of light and would get too hot on a
sunny day. Keep them well watered, watering in the mornings if you can.
Plants sitting in wet compost cope less well with a night-time drop in
temperature.
You can do all this on a windowsill, though it is difficult to give the
plants enough light to stop them becoming leggy. If you are turning
plants round to expose different sides to the light remember not to
always turn them in the same direction: they can twist themselves off
their stems as they grow to follow the light!
A January sowing of sugar peas, in root trainers or short lengths of
guttering, will ensure a welcome crop of sugar peas in May. Calabrese
and cauliflowers can also be down in January, potted on and planted out
for an early summer crop.