Gardening month by month: December

December in the Garden

 The nights are drawing in, the shortest day is coming up, and the Yule celebrations are on most people's minds now. So there's no gardening to be done at this time of year... right?

Wrong! Whilst the seed packets might be tucked up in their biscuit tins for the winter, there's still plenty that can be done in, and for, the garden in December.

Sowing

Garlic and autumn onion sets can still be sneaked in this month before the New Year. Cover these with twigs, netting or cotton to deter birds from pulling the cloves back out of the ground.

Planting out

For one thing, the middle of winter is an ideal time to plant and prune some bare rooted top fruit trees such as apples and pears. The trees are dormant at this time of year, which means that the shock of transplanting or pruning is much reduced. Planting a tree is a fairly simple affair - you basically dig a hole big enough for the roots to sit in, put the tree in the hole and then backfill the soil into the hole, making sure to firm it round with your boot. Ensure that the soil comes up to the same mark on the trunk as it was originally. If you cannot see where this mark is on a bare rooted tree, look for the grafting joint between the rootstock and the top part of the tree (known as the ‘scion'). The soil should be around 2"/5cm below this point. A top dressing of an inch or two of compost or well rotted manure can be laid around the tree now - this will serve double duty at keeping competing weed growth down and also slowly being pulled down by earthworms to feed the tree gradually as it bursts back into life later in the spring.

A wooden stake can be used to support the young tree. Traditionally this was put in vertically next to the trunk and tied to it at two or three places. However modern thinking is that putting the stake in at 45 degrees offers a number of advantages. First, the stake will not be passing through the root ball but rather to one side, so that it is less likely to damage smaller roots whilst it is being driven into the ground. It is also less likely to rub on the trunk as it is fixed to the stake at only one point. The stake can be angled in such a way as to provide the maximum support for the sapling against the prevailing wind, which is also useful on a windy, exposed site. The attachment between the tree and the stake should be made using flexible material that is not likely to cut into the growing trunk. Suitable ties can be purchased from garden centres or, in keeping with our recycling ethos, old nylon tights or stockings can be used. The stake and tie will need to stay in place for a couple of years, until the trunk has matured, so it is important to check the ties every so often and loosen them if they appear to be too tight.

Pruning fruit trees is a subject that whole books have been written about and there are many techniques for training trees in particular ways. However for a simple upright tree, the basic pruning is relatively simple. Most trees that are purchased are already over a year old, so for the first three to four years of ownership the branches should simply have a third of their length cut off, preferably just above an outward facing bud. Any damaged or diseased branches should also be pruned back to good wood. Once over five or six years old the tree is mature and pruning is then aimed at keeping the centre of the tree clear, preventing branches rubbing on one another and removing damaged and diseased boughs. If you inherit an old, unkempt tree, you can also do some winter pruning to help rejuvenate it. The aim is much the same as with pruning a mature tree, but you might want to spread the pruning of large numbers of branches over a couple of years so that it doesn't come as too much of a shock to the plant. Remove diseased, damaged and overlapping branches first and then in the subsequent years remove branches that cross through the centre of the tree, with the aim of eventually giving the branches an open ‘bowl' shape. One last thing to note is that whilst apples and pears are happiest being pruned in midwinter, pruning of plums and damsons is best left until the middle of summer, as they are susceptible to being infected by a disease called silverleaf which finds it easier to take hold during the winter period.

Harvesting

Jerusalem artichokes should be lurking underground waiting to be harvested.

Brussel sprouts should be just about right now - but please don't just boil them to death and give ‘em to the kids with Christmas lunch. No point putting them off for life!

Spinach or spinach beet should be OK still - just harvest the leaves as required.

Swedes and turnips can be lifted if they haven't already been brought in - you can keep them in boxes of sand or straw in a garage, shed or outbuilding.

Salsify and scorzonera can be harvested from this month.

If you've any marrows still growing, cut them and get them inside now.

The leek season starts this month - lift them as you need them.

Seakale/beet may have a few last harvestable crops this month.

Other jobs

OK, what else can be done aside from playing with fruit trees? Well, if you are lucky enough to have a greenhouse or polytunnel and have not yet got round to cleaning it, the next few months will be your last opportunity before it starts filling up again in the early spring. Clear out any debris and old plants left over from the previous growing season and wash down the staging. If you grow in beds in the ground (rather than in pots or growbags) you might also want to consider changing the soil over now to minimise the chances of overwintering pests and diseases from last year's crops spreading to next year's new plants. This is especially important if you tend to grow the same types of plants in the same place every year.

Even if you don't have the benefits of a greenhouse or polytunnel there's plenty of tidying up that can be done, including some things that can be done indoors on the long, dark, cold winter nights. Pot plants that are dead or too old can be turned out into the compost bin and the pots that have been used in the last year brushed clean and then washed. To save water the pots can be washed in used washing up water or bath water. Having a stack of clean pots ready to start sowing and planting can be a real boon come the busy times in April and May!

Don't forget the local wildlife in your garden. An organic gardener feeds the soil first, but they should also be feeding and housing potential allies in the war against pests. If you have mulches down over the ground you might want to move them to one side every so often and give the ground a bit of a rake over. This will expose grubs, slugs and snails that the birds can feast on for a day or so before the mulch is moved back over the ground. An area of rough ground with some wood and/or leaves piled up can give insects and small predators somewhere to hole up during the cold weather. This ground can be round the back of the shed or underneath a hedge - far enough away from growing areas for pests to find it unattractive but unlikely to be disturbed.

The last thing to do over the winter is to sit back, quaff a mug of tea and plan out what you are going to do next year. Look at what worked for you this year, and also what didn't. Work out what construction jobs you need to do before the next season and have a browse through seed catalogues. If you want to order particular varieties of seed potatoes many horticultural suppliers will only guarantee deliveries if the orders are placed before the New Year - getting your orders in can ensure that you get what you want rather than what's plentiful next year. That new growing season is getting closer by the day!

Jim'll

Photographs (c) Sabrina Willekens 2008