Sowing
You can still sow onions in small pots indoors to have them ready for planting out in spring.
Sow radish in modules ready to plant out in spring.
Continue with salad leaves and beets, even on the coldest weeks.
You can still sow broad beans.
In the south you can sow peas later in the month, in sheltered positions. Use a cloche for best results.
Growing
Shallots should be planted on the shortest day and harvested on the longest, and just try one pickled shallot from last year with some mature cheddar – just to remind you why you are doing it!
Put well rotted manure and then straw on rhubarb crowns – around 30cm deep to give them an extra boost.
Early in the month check your new potatoes growing indoors for Christmas, make sure the tubers are well covered so they don’t green up.
Forcing rhubarb – you can dig up clumps of rhubarb and put them in a decent pot, preferably ceramic. Cover the pot in a stout box that cuts out the light and trigger the plant’s growth by warming it up in a shed or greenhouse.
Maintenance
A spade dug in December is worth three in March. Dig and incorporate as much organic material as you can – some manure, some compost.
Your brassica patch would do well with a really good application of lime, a spade-full per square metre. This will help control clubroot.
Clean up the garden by collecting fallen leaves, old plants, fallen crops, old cabbages and sprouts. Remove anything that is rotting and have a look out for anything that might introduce disease.
Remember to lag and protect any outside water pipes against the cold.
Make sure you think about wildlife – leave some ‘untidy’ bits, piles of sticks, and don’t forget to feed the birds!
Pests
You still get over-wintering insect pests – look out for whitefly, especially on sprouts when you pick them on Christmas Morning! You will see a lot of chafer grubs when you are digging. As a rule of thumb, a healthy soil has both carnivores and herbivores. You don’t have to kill every insect you see in the soil, they will eat each other over the coming months.
What to do in your garden in December
December is more than just Christmas, so take some time out for the garden because there is lots to do!