Garden Notes for December 2020.
What a wonderful autumn display of colours by the trees in November! Better than any firework display, in my view. Of course it is all down to the weather we have had previously. Now the plants have their winter ‘sleep’, and it is probably best to let them lie in peace. However there are a number of things you can do, as ever – a Gardener’s work is never done.
Large flowered clematis, like Clematis jackmanii and the many hybrids from it, should be pruned towards the end of the month. They can be cut back quite severely. Prune back to good, well developed buds.
Seeds of helleborus, hosta and primula can be sown in December and January. Use John Innes No.1 compost (or similar) covering the seed with a thin layer of compost. After watering them in, place the seed container against a North wall or in a cold frame making sure that they are protected from mice. Leave them there until the spring. Then bring them into a greenhouse, on a well lit, but not sunny place, and germination should then take place.
If you are planning to sow hardy annuals in the spring, they will benefit from giving the soil in the place they will go to an early preparation. So long as the soil is in reasonably good heart it is best not to put any fertiliser, since annuals do best in a soil that is not too rich.
When picking Brussels sprouts keep the tops, and only use the best when all the sprouts have been harvested. Some of the winter broccoli may be starting to form their curds. Turn in the leaves to protect the curd from frost, and cut regularly as once they have reached their full development the curds soon begin to open and will spoil.
In order to have some early shoots of mint, now is the time to lift a few roots and put them in a fairly deep seed box and cover with potting soil. Put it in a frame or the greenhouse, and you will have nice shoots in a few weeks, when everything else is still asleep in the garden.
If you are lucky enough to have a greenhouse vine, they should be pruned towards the end of the month. All side-growths should be cut back to two buds. The spurs carrying these shortened growths should be well spaced apart, at least 40 to 50 cm apart on the main rod so that overcrowding in summer is minimised.