December is realistically not the most popular month for gardening. Frost, rainfall – perhaps even snow – and dull, short days hardly encourage one to go outside for too long.
The sharp frost a couple of weeks ago certainly put an end to many of the autumn flowers and reminded us why we move some of our tender perennials, such as Cannas and Dahlias, under cover. Even some fully hardy plants, such as Hydrangeas, had their foliage blackened, although we know these will bounce back in the spring.
So what do gardeners do in December – apart from armchair gardening, that is?
Firstly, greenhouses need a regular visit. Dead or dying foliage needs to be removed before it has chance to rot and spread diseases such as Botrytis (grey mould) to other plants. If you do heat your greenhouse, keep an eye on heaters as it only takes one cold night to chill those plants.
If you do not heat, frost protection fleece can be very handy for keeping tender plants snug over winter. Even more important is to keep your plants as dry as you feel possible, as they can withstand much lower temperatures this way.
Ventilation is often overlooked in greenhouses during winter. The doors or main vents may be opened on all but the coldest of days as humidity can soon build up which will also encourage disease. I like to keep the low level louvre vents open all the time to ensure good air flow.
There are also jobs that can be done in the garden – on the nicer days! I generally like to leave border plants alone until the spring; the old foliage give protection to both the plant and to overwintering insects and can often look quite attractive when covered in frost.
However we do cut the leaves off the Lenten Roses, Helleborus hybrids, to enable the flowers to be nicely displayed in the spring without the old leaves in the way. We do not do this to the Christmas Roses, however, which are already looking great!
Pruning of fruit trees and bushes, as well as many other deciduous trees and shrubs, can be done anytime over the next few weeks. However some, such as Acers, Birches and Vines, should be pruned sooner rather than later as they can bleed if left until spring.
Many prunings may be used for my favourite pastime – propagation. Winter may not be the most obvious time for taking cuttings, but hardwood cuttings are very easy and undemanding! For most plants, a piece of the current season’s wood, around pencil thickness and length, is ideal. Cut with a slant above the top bud, straight below a bottom bud, and insert around two-thirds of its length (the right way up!) in either a deep pot, or into a prepared bed. Water in, then practically forget about them until next summer when you will see new growth. What can be easier!
This is a great way of growing new specimens of Buddleja, Forsythia, Cornus (Dogwoods), species Roses, climbers such as Vines, Honeysuckle and Jasmine – in fact, almost any deciduous shrub and many trees.
- Manea School of Gardening (RHS approved centre)