What to do in December
Down at the allotment the big dig has started! Preparing the soil for next year’s crops. If you add your well rotted manure now and you are gardening on chalky or sandy soil it is a good idea to cover it over – if not, over the winter time, you will find that the rains will wash out a lot of the nutrients that manure provides. Black polythene can be used for this, and it will also keep down the weeds at the same time so be sure to pull them out as you dig.
Clean out and wash all your seed trays, pots and other containers – it really is worth doing, it will save you lots of frustration when spring comes. I think the best way to do it is to soak all your pots etc in a tub trug to loosen the soil and then use a washing up brush to get into the corners.
If you still have root crops, such as carrots, beetroot, and turnips then lift and store these before the weather gets worse. You can leave parsnips in the ground and then lift them when needed.
If you have a greenhouse then do spend time now, if you haven’t already done so, insulating it. It is easy to get bubble wrap free and it really does make quite a difference, a couple of degrees warmer and of course, with your horticultural fleece to hand, if there is a frost, you may well save some of your plants.
Alpines can be sown from seed in December. They need a period of cold to break the seed dormancy. (Wake the seeds up). A sheet of glass can be put over the sown seeds to protect them from excessive wet. Alternatively, the seeds can be stratified (that means kidding them they have gone through a winter) in the fridge, for sowing next spring.
Keep cutting back herbaceous perennials when they have died and add them to the compost heap.
In mild areas, and during dry spells, you can still lift and divide herbaceous perennials. This will increase stocks, and revive tired or poorly flowering clumps. Simply dig up your clump of plants, e.g.: Geraniums, Hostas, and using a spade, or two forks back to back or for really tough jobs use a pruning saw, and divide the plant into three or five clumps, discard the middle woody part as it is not like to flower very well. Replant the divisions and give some away to your allotment neighbours.
Check on tender plants outdoors to ensure winter protection is still in place, especially after storms.
Finish the autumn tidy-up of leaves from beds and borders if you have not already done so. It is especially important to clear leaves and debris, as plants will die off if covered in damp for any length of time. Keep tubs and containers tidy too, cutting back and removing debris regularly. They can be mulched with compost.
Improve the drainage of heavy clay soils by working in plenty of bulky organic matter, such as composted bark.
If you have large terracotta pots that are at risk of cracking in the frost cover with bubblewrap, hessian or fleece, to insulate them over the winter.
Tender plants and pots can be brought into the greenhouse. Even in mild areas, the winter usually gets much harder after December.
Look out for Botrytis (grey mould) on dying herbaceous plants, and remove affected growth. Otherwise there is a risk that fungal problems could spread to healthy plants.
Sometimes daffodils can come up very early, even before Christmas. Enjoy them, but be aware that they too can succumb to fungal problems, such as narcissus leaf scorch.
Remember that many diseases will overwinter in the soil, or on plant debris. So now is a good time to have a tidy up.
It’s easy to grow grapevines on an allotment, but unless you have a glass house, you’ll be limited to growing wine grape varieties, as dessert grapes need more warmth.
They need as much warmth as is possible to grow and for the fruit to ripen. Don’t plant them in a frost as a single frost in the last spring will destroy the emerging shoots and flowers. You can train them over an arch or the best and simples way of training them is to grow them vertically on a post and prune them once they are dormant – if not it can lead to severe bleeding which will weaken the wine and can kill it. This years side shoots should be hard pruned to one or two buds. The buds are where there is a ‘protrudence’ on the stem –leaf buds tend to be flat and fruit buds are fatter. You can identify this years shoots as they will be paler in colour than the older wood.
If you have free standing apple and pear trees, now is a good time to prune them, but not cordons, espaliers, pyramids or fans, which should be left until summer. Pruning of stone fruits such as plums, apricots and peaches should be left until summer – if not they may suffer from silver leaf, which is a fungal disease, and die.
With apples and pears make sure you plan your pruning –don’t prune for the sake of it. Start off by thinking about the four Ds
Growth that is crossing can rub on other branches and cause pests and diseases.
Branches that are too low can be removed or those that are too tall.
You are aiming or a goblet shape which can allow a bird to fly through the middle. It is not a good idea to remove more than a third of the tree – if not you will find yourself with lots of epicormic growth, (that is unproductive). Use a good pair of loppers or a pruning saw for this job.
If you have red currants and gooseberries they can be pruned now. Prune out the old, very thin and diseased growth. This will invigorate the plant. If you have black currants, cut back a third of the old branches down to the ground, this will allow new shoots to come from the base and fruit for next year. Bullfinches may want to come and eat the flower buds so suspend some fruit netting on flower pots that are balanced on canes to keep them off your fruit bushes.
Asparagus is a great vegetable to grow; now is a good time to prepare a new bed to plant in the spring. They need lots of organic matter and can last up to and beyond 25 years so it is well worth preparing for them well. Make a raised bed as they do need well drained soil.
Finally, have a review of the year on your allotment – if things have been successful then do grow them again, if not do it differently next time – gardening is very forgiving! The weather plays a very important role in how things grow, or maybe you sowed things too early, two close together, or maybe a drought means fewer runner beans and fruit. Now is a good time to check out which cultivars are disease resistant and which one grow in cold or hot weather. Of course considering if you liked the taste of your vegetable and fruit varieties is also an important factor.
Do keep a journal – it really will help you to become a good allotment holder.