Continue last month's pruning of roses whenever the weather is pleasant enough to work outdoors. Remove long straggly branches that can get blown about and damaged in a strong wind. In mild winters, you may even find the odd flower bud on recurrent roses, which are a treat to pick and take indoors.
Roses that suffered from black spot in the past can be sprayed with a suitable fungicide this month. Prevention is often the best cure and keeping the ground beneath roses free of all dead leaves or other debris is as important as spraying, as fungal spores tend to collect and over winter there.
Earthworms can also be a problem, although they do not damage the grass, the casts they leave on the surface of the lawn are a nuisance and can cause weeds and moss to take hold. Therefore it is best to sweep them off the lawn as soon as they appear.
Planting of new roses can continue through December, as long as the soil is workable. Check any roses planted last month, to see that they haven't been lifted by frost. Firm them back into the soil, if necessary.
Container-grown and root-wrapped or bare-rooted hedging plants, trees and shrubs can all be planted now, provided that the weather is mild and the soil is in good shape. All tree stakes should be checked and replaced if necessary. Most trees will be self-supporting after three or four years, and there is seldom any point in having a stake beyond that time. Ties should also be examined and slackened off if at all tight.
Check your defences against frost, adjusting screening or protective coverings if they have come adrift.
If the weather is harsh for long periods, watch out for rodents, rabbits and deer eating the bark of young shrubs, because their usual source of food may be unavailable. If you live in an area that is susceptible to attack from such animals, use purpose-made, perforated plastic tree guards or similar protection. The height of protection needed depends on the animal involved and there is very little you can do if deer take, a fancy to your shrubs and low tree branches but young standards, half standards and bush trees should have their entire trunk protected.
Pot, container and tub planted ornamental trees and shrubs will still need watering, if the weather has been warm and sunny. If it has been wet and windy then also check for wind rock. The latter occurs when a plant takes the full force of the wind, and a hollow forms in the soil or compost round the base of the stem or stems. Newly planted trees and shrubs are particularly vulnerable, as their roots have not yet had time to become established.
You can start pruning Clematis 'Jackmanii' and other late flowering clematis now, or you can leave it until later in winter, depending on the weather.
Root cuttings can be taken from shrubs this month; the method is the same as for root cuttings of herbaceous plants. See our section on Propagation from Cuttings.
Next page >> What to do in the Vegetable garden in December >>
For coloured stems and bark see November
Deciduous trees and shrubs for winter colour:
Hamamelis (witch hazel)
Viburnum (Farreri and Bondnantense)
Winter honeysuckle (Lonicera fragrantissima and purpusii)
Evergreen trees and shrubs for winter colour:
Erica (many cultivars)
Hippophae rhamnoides (sea buckthorn)
Laurustinus (Viburnum tinus)
Winter flowering jasmine (Jasminum nudiflorum)