5 December marks the UN’s World Soil Day
- Garlic can still be planted. Place bulbs 1 inch deep (2.5 cm) in well-drained soil.
- Tidy winter brassica beds, weeding and removing any yellow or unhealthy leaves. Stake plants such as brussels sprouts to avoid wind rock. Keep bird netting secure.
- If temperatures drop, move blueberries in containers into a garden shed, or wrap the pot in hessian or straw to protect from frost damage.
- Prune currant and gooseberry bushes.
- Prune grapevines while dormant. (Pruning when sap is running causes wounds to bleed, which can weaken plants and reduce harvests.)
- Prune freestanding apple and pear trees. Remove crossing branches, and any branches that are dead, diseased or damaged. Shorten the previous year’s growth on main branches by about a third. Occasionally if trees are very large they may need periodic, harder renovation pruning.
- In December do NOT prune stone fruit such as cherries and plums until late spring to avoid silver leaf disease. (RHS, The Garden, Dec 2014, p.23).
- If you are lucky enough to have wall-trained peaches & nectarines, take time to erect a rain shelter over them to protect against peach leaf curl diseases. Leave the rain guard in place until mid-May.
- Fig trees can be fleeced to protect branch tips and embryo fruits from frost damage. Wall trained figs can be packed with straw or bracken.
- December is a good time to divide and replant rhubarb if overgrown. For early, tender stems you can ‘force’ rhubarb by covering crowns with a layer of straw. Exclude light with a dark-coloured bucket.
- Continue harvesting winter greens crops (spinach, kale, brussels sprouts, leeks and winter cabbages etc).
- Ventilate greenhouses on mild days to reduce disease and mildews, for plants to be planted out next autumn. Deciduous and evergreen species are suitable. Raise in a well-drained sheltered spot, or in a cold glasshouse.
- Hardwood cuttings can be made from late autumn to midwinter
- Citrus care: Only water citrus when the compost is dry an inch down, and then only water until it exits the drainage. Soak thoroughly rather than watering little and often – which can lead to root loss.
- Fertilise citrus monthly in winter (October to March) with a high-potassium feed with trace elements, such as a tomato fertiliser.
- Lemons etc need a minimum night temperature of 10 degrees Celcius.
- Increase humidity for the plants by placing their pots on trays of damp gravel. Keep water level just below the gravel surface. You can also hand-mist regularly.
- Be careful not to overwater citrus over winter. They should partially dry out between waterings.
Flower / Ornamental Garden
- Ensure outdoor containers do not dry out.
- Prepared potted bulbs planted in autumn can be brought indoors now, into a cool room, ready to flower for Christmas.
- Tidy and deadhead flower beds as needed.
- Apply a ‘dry’ mulch (eg chipped bark) to overwintering dahlias.
- If necessary, prune Japanese maples while they are fully dormant. Remove crossing branches. You can also reduce the overall size by taking long growth back to lower side branches.
- Check climbers tied to supports and trellises to check they are securely tied to prevent winter wind damage.
- December is the traditional time to coppice or pollard trees such as hazel.
- Continue taking hardwood cuttings from deciduous trees, shrubs such as buddleia and climbers.
- Take hardwood cuttings 8 inches long of deciduous shrubs such as Callicarpa, Tamarix and viburnums.
- Cut above a node at the top and below a node at the base.
- Insert cuttings deeply into a prepared cutting bed (outdoor, in ground), so that only a third remains above the soil surface.
- Take root cuttings from perennials like Verbascum, Acanthus and oriental poppies. Insert 2-4 inch cuttings into compost and overwinter in a cold frame – they will be ready to pot-up individually in spring.
- Robin remain active all winter.
- Some birds migrate to Britain during winter, fleeting harsher weather from their breeding grounds further north in Europe, like Iceland and Scandinavia. Birds of this type include: Fieldfares; Redwing (the smallest thrush in the UK); Bramblings, (which feed on the fruit from Beech trees), and, more rarely, Waxwings.
- Hang bird feeders and leave berries on plants and holly trees to provide food for birds in lean winter days.
- Clean birdbaths.
- Be careful when tidying not to disturb hibernating toads, frogs, and ladybirds.
- Frogs, toads and newts seek sheltered placed to hide during winter, such as rotting leaves, logs, compost heaps, etc. Be careful about disturbing wild spaces around the pond area all through winter. In other words, a messy patch is a wildlife friendly patch!
- UK butterflies and moths spend winter as caterpillars or pupae lying dormant at the base of plants or wrapped in loose silk. They can survive most winters, and become active in spring. Peacock butterfly and Small Tortoiseshell butterfly overwinter as adults in dark, sheltered spots like holes in trees and brickwork; they emerge in the first warm spring days to feed on nectar and start mating and laying eggs.