Usually December means hard frosts and it’s time to harvest winter cabbages and cauliflowers. The Brussels sprouts should be starting.
Leeks should be about ready, just take what you need and leave the rest to stand until required.
Lift celery, parsnips and swedes although parsnips and swedes are very hardy and may be left if the ground is not needed.
It’s worth checking any vegetables you have in store and removing anything that has started to rot before it spreads. Potatoes especially need to be checked and watch out for slugs that have emerged from a potato to go and damage another one.
Other crops you may have for harvest:
Perpetual spinach, celeriac, chicory (non-forcing and forcing varieties), endive, kale, kohl rabi, lettuce, winter radish, spinach, turnips.
General Jobs in the Garden
Digging can continue, when weather allows. Particularly with clay soils, digging when the soil is wet and sticky can do more harm than good.
As with October & November, as ground becomes vacant, you can dig it over and spread manure over the surface. Leave the soil roughly dug in large clumps and the worms will break these up as they get the manure. The freezing and thawing of water in the soil will cause the soil to break up finely so becoming easier to handle in the spring.
Winter is a good time to undertake double digging, incorporating manure into the bottom of the trench and deepening your topsoil.
Ensure compost bins are covered to prevent excess rain leaching the nutrients and to keep some of the heat of decomposition in.
Try and keep things tidy to avoid providing winter homes for pests waiting for the spring.
Take hardwood cuttings of soft fruit. Gooseberries, red, white and black currants, worcesterberries, jostaberries and vines can all be propagated by cuttings inserted in the open ground now. Choose sturdy well ripened shoots of this year’s growth cutting them just below a bud and trimming to just above a bud. For black currants take them about 8-10 inches (200-250 mm) long, 12-15 inches (300-380 mm) for the other fruits. Insert them into the soil to about half their length.
Sowing, Planting and Cultivating
You can still plant your garlic cloves now. They actually benefit from a period of cold, which prompts growth later.
You can plant bare rooted fruit trees and bushes in December and prune apple and pear trees. Now is a good time to plant rhubarb crowns which will benefit from being left out to be frosted before planting.
Check any young trees are well supported with stakes and ties. Stakes can tend to work loose, which means they won’t be doing their job of preventing wind rock loosening the roots.
You can prune your apple and pear trees now.
December is the traditional month to go through the seed catalogues, decide what you want to grow and make a list.