December often tempts gardeners to hang up their tools and retreat indoors. But there’s much to be done if you want to set your garden up for success in the year ahead. Winter gardening may lack the vibrant colour of spring or the abundant harvests of summer, but it offers its own rewards: the crisp air, the quiet satisfaction of a well-tended plot, and the knowledge that you’re giving your plants the best possible start.
From protecting tender specimens against frost to harvesting robust winter vegetables, December is a month of preparation and preservation. Whether you’re nurturing houseplants through their dormant period or taking advantage of bare-root planting season, these ten essential tasks will keep your garden healthy and thriving through the coldest months.
Let’s explore what needs your attention this December.
1. Reduce Watering of Houseplants
As winter sets in and daylight hours dwindle, your houseplants enter a period of dormancy. Growth slows considerably, and their water requirements drop accordingly. Over-watering during this time is one of the most common mistakes gardeners make, leading to root rot and fungal diseases.
Check the soil before watering. Push your finger about two centimetres into the compost—if it feels moist, hold off. Most houseplants will need watering only every two to three weeks during December, though this varies depending on your home’s temperature and humidity levels. Cacti and succulents may not need water at all.
Plants positioned near radiators or in particularly warm rooms may dry out faster, so adjust accordingly. Remember that terracotta pots allow moisture to evaporate more quickly than plastic ones, which means plants in these containers might need slightly more frequent attention.
2. Keep Mice Away from Stored Produce
Root vegetables stored in sheds, garages, or outdoor clamps make tempting targets for hungry rodents seeking winter shelter. Mice can devastate months of careful cultivation in just a few nights, nibbling through potatoes, carrots, and beetroot with remarkable efficiency.
Store your produce in sturdy, lidded containers made of metal or thick plastic that mice cannot gnaw through. Wooden boxes should be lined with fine wire mesh. Inspect your storage areas for entry points—mice can squeeze through gaps as small as a pencil’s width. Block these with steel wool, which they cannot chew, or use expanding foam combined with wire mesh for larger holes.
Traditional mousetraps remain effective, but check them daily to dispose of any casualties humanely. Alternatively, consider natural deterrents such as peppermint oil on cotton wool balls placed near stored produce. Cats, of course, are nature’s original pest control, though not every gardener has access to a feline assistant.
Keep storage areas tidy and free from fallen produce, which attracts mice in the first place. A clean, well-organized space is far less appealing to unwanted visitors.
3. Take Hardwood Cuttings
December is an excellent time to propagate many woody plants through hardwood cuttings. This simple technique allows you to create new plants from mature growth, perfect for roses, currants, gooseberries, willows, dogwoods, and many ornamental shrubs.
Select healthy shoots from this year’s growth, choosing pencil-thick stems about 20 to 30 centimetres long. Make a straight cut just below a bud at the base and an angled cut above a bud at the top—the angle helps you remember which end is up and allows water to run off. Remove any remaining leaves.
Insert your cuttings into a slit trench in a sheltered spot outdoors, burying about two-thirds of each stem. The soil should be well-drained but moisture-retentive. Space multiple cuttings about 15 centimetres apart. You can also root them in deep pots filled with gritty compost, which is useful if your soil is heavy clay.
By next autumn, most cuttings will have developed sufficient roots to transplant to their permanent positions. This method costs nothing and can quickly fill gaps in borders or hedges.
4. Harvest Leeks, Parsnips, Cabbage, Sprouts, and Root Crops
Winter vegetables truly come into their own during December. Cold weather actually improves the flavour of many crops, particularly parsnips and Brussels sprouts, as low temperatures convert starches to sugars.
Leeks can be harvested as needed throughout winter. Use a fork to loosen the soil around the base, then pull gently to avoid breaking the shaft. Harvest from one end of the row to the other rather than taking plants randomly, which makes subsequent harvesting easier.
Parsnips benefit from frost exposure before harvesting—the cold sweetens their flavour considerably. Lift them carefully with a fork to avoid damaging the roots. They can remain in the ground until needed, but if severe frost is forecast or your soil is heavy, lift and store them in boxes of barely moist sand.
Brussels sprouts should be picked from the bottom of the stalk upwards, snapping off individual sprouts when they’re firm and tight, about the size of a walnut. Don’t strip the entire plant at once; harvest over several weeks as the top sprouts continue to mature.
Winter cabbages and root crops like carrots, beetroot, and turnips can be lifted as required. In milder regions, they’ll keep perfectly well in the ground under a thick layer of straw or bracken. In colder areas, store them in boxes of sand in a frost-free shed.
5. Prune Acers, Birches, and Vines Before Christmas
Certain trees and woody plants “bleed” sap profusely if pruned during their active growing season. Acers (Japanese maples), birches, and grapevines must be pruned during their dormant period, ideally before Christmas, to minimize this sap loss.
When sap bleeds from pruning cuts, it weakens the plant and creates entry points for diseases. By pruning in December, you reduce sap flow to a minimum. The wounds will callus over during the dormant season, ready for healthy growth in spring.
For acers, remove any dead, diseased, or crossing branches that might rub against each other. Aim to maintain the tree’s natural shape rather than imposing a formal structure. These elegant trees rarely need heavy pruning—light touch-ups every few years suffice.
Birches require minimal pruning. Remove only damaged or awkwardly placed branches, cutting back to a main branch or the trunk. Never leave stubs, which invite decay.
Grapevines need more substantial pruning to maintain productivity. Cut back the previous season’s growth to two or three buds from the main framework. This encourages the formation of fruiting spurs for next year’s crop.
Always use sharp, clean secateurs to make smooth cuts, and sterilize blades between plants to prevent disease transmission.
6. Prune Open-Grown Apples and Pears
December is perfect for pruning free-standing apple and pear trees, but avoid pruning those trained against walls or fences until summer. The distinction matters because wall-trained trees require different treatment to control their vigorous growth and maintain their restricted form.
Open-grown trees benefit from winter pruning while dormant. This allows you to see the tree’s structure clearly without foliage obscuring your view. Start by removing the “three Ds”: dead, diseased & damaged. Then thin out congested areas to improve air circulation and light penetration. Take out any crossing branches. These actions will reduces disease and improves fruit quality.
For established trees, aim to create an open, goblet-shaped structure with a clear centre. Remove any shoots growing into the middle of the tree or directly upwards. Cut back vigorous vertical shoots (water shoots) to their base—these rarely produce fruit and sap energy from productive wood.
Make cuts just above outward-facing buds to encourage growth away from the tree’s centre. Angle cuts slightly to shed water, and use sharp tools to avoid leaving ragged edges that heal slowly.
Wall-trained trees (espaliers, cordons, and fans) are pruned in summer instead because winter pruning would stimulate excessive leafy growth at the expense of fruit. Summer pruning restricts growth and encourages the formation of fruiting spurs.
7. Insulate Outdoor Taps and Prevent Ponds from Freezing
Water features and outdoor plumbing need protection as temperatures drop. A frozen tap can burst, causing expensive damage and leaving you without water when you need it most.
Insulate outdoor taps with purpose-made insulation sleeves or improvise with layers of bubble wrap secured with waterproof tape. If possible, turn off the water supply to outside taps at the stopcock and drain the pipes. This eliminates the risk entirely.
Garden ponds require attention too. If ice covers the surface for extended periods, toxic gases from decomposing organic matter become trapped beneath, potentially harming fish and other aquatic life. Never smash ice with a hammer—the shockwaves can injure fish. Instead, place a pan of hot water on the surface to melt a hole gently.
Floating a tennis ball or rubber ball on the pond’s surface helps prevent complete freezing by absorbing some of the ice’s expansion pressure. For more reliable protection, invest in a pond heater designed to keep a small area ice-free, allowing gas exchange to continue.
Remove dead leaves and debris from the pond regularly. Stretched netting over the surface in autumn prevents most leaves from entering, reducing maintenance later.
8. Sort Out Greenhouse Heating
Your greenhouse protects tender plants from winter weather, but many specimens need additional warmth to survive the coldest nights. December is the time to ensure your heating system is functioning properly before a sudden cold snap causes disaster.
Electric heaters with thermostatic controls offer the most precise temperature regulation. Position them centrally for even heat distribution, and keep them away from water sources. Check that electrical connections are secure and cables undamaged. Test the thermostat by adjusting settings and confirming the heater responds correctly.
Paraffin heaters provide a budget-friendly alternative but require more attention. Ensure adequate ventilation to prevent harmful fumes accumulating, and keep wicks trimmed for efficient burning. Refill regularly—running out of fuel overnight could prove fatal to your plants.
Insulating the greenhouse reduces heating costs significantly. Bubble wrap attached to the inside of glass panels traps air while still admitting light. Secure it with special clips designed for the purpose, leaving ventilation points clear. For even better insulation, use horticultural bubble wrap with larger bubbles than standard packaging material.
Close vents and doors at dusk to retain daytime warmth, but open them during mild spells to prevent humidity buildup, which encourages fungal diseases.
9. Put in Place Winter Protection on Structures
Garden structures face battering from winter storms and frost damage if left unprotected. Taking preventative action now saves costly repairs later.
Clean and treat wooden structures such as pergolas, arches, and fences. Remove algae and moss with a stiff brush, allow surfaces to dry, then apply a wood preservative or weather-resistant stain. This protects against moisture penetration and rot. Check for loose fixings and replace damaged sections before strong winds exploit weaknesses.
Empty terracotta pots and move them under cover if possible—porous clay absorbs water, which expands when frozen and cracks the pot. If pots must remain outside, raise them on pot feet to improve drainage and reduce frost damage. Wrap valuable containers in bubble wrap or hessian.
Secure loose items that could become projectiles in high winds. Store garden furniture cushions indoors, or at minimum, in weatherproof storage boxes. Check that shed roofs are sound and gutters are clear of debris that could cause blockages and leaks.
Inspect supports for climbing plants. Ties can rot and break during winter storms, leaving plants damaged. Replace worn ties and check that trellis panels are firmly attached.
10. Plant and Transplant Trees and Shrubs
“Plant bare-root when the ground is bare” goes the old gardening saying, and December offers ideal conditions for establishing woody plants. Bare-root trees and shrubs, lifted from nursery fields and sold without pots, are cheaper than container-grown specimens and often establish more successfully.
The dormant season allows plants to develop root systems before spring growth begins. Soil remains workable unless frozen solid, and winter rainfall helps settle roots without requiring constant attention from the gardener.
Choose a mild day when the soil is neither frozen nor waterlogged. Dig a generous planting hole, breaking up compacted soil at the bottom to aid drainage. The hole should be wide enough to spread roots comfortably but no deeper than the soil mark visible on the stem—planting too deep encourages rot.
Mix excavated soil with well-rotted organic matter if your ground is poor. Position the plant, backfill gradually, and firm gently with your heel to eliminate air pockets. Water thoroughly even in winter—this settles soil around roots and is crucial for establishment.
Stake trees loosely, allowing some movement that encourages strong root development. Use a tree tie with a buffer that prevents bark damage. Apply a mulch layer around the base, keeping it clear of the stem itself, to suppress weeds and conserve moisture.
Transplanting established shrubs also works well during December dormancy. Prepare the new planting site before lifting the shrub. Dig around the root ball, keeping as much soil attached as possible, and replant immediately. Water well and mulch. Most deciduous shrubs move successfully during winter, though evergreens may struggle.
FAQ
Can I do any of these jobs if the ground is frozen?
Avoid working the soil when frozen solid, as walking on it damages structure. However, tasks like pruning, protecting structures, and checking greenhouse heating can proceed regardless. Wait for a thaw before planting, transplanting, or harvesting root crops.
How do I know if I’m overwatering my houseplants?
Yellow, drooping leaves and soft, mushy stems indicate overwatering. Healthy roots are white or cream; rotted roots turn brown and smell unpleasant. If in doubt, let the compost dry out slightly between waterings.
What if I miss the December deadline for pruning vines or acers?
They can be pruned cautiously in January, though sap flow increases as the season progresses. Avoid pruning after February when bleeding becomes excessive. If you must make emergency cuts later, seal wounds with pruning paint, though this isn’t generally recommended for most pruning.
Can I harvest vegetables after a hard frost?
Some crops like parsnips improve after frost, but leafy vegetables may be damaged. Harvest on a mild day when foliage has thawed completely. Cutting frozen leaves causes severe damage.
Your Garden’s Winter Foundation
December gardening may lack the glamour of summer’s abundance, but the work you do now lays the groundwork for a thriving garden throughout the coming year. These ten essential tasks protect your plants through harsh weather, maintain healthy growth cycles, and ensure you have the fresh produce and beautiful specimens you’ve worked so hard to cultivate.
Winter gardening offers its own quiet pleasures—the satisfaction of a properly mulched bed, the promise held in a bundle of hardwood cuttings, the assurance that your pond fish will survive the freeze. Step outside on a crisp December morning, and you’ll find that the garden still needs you, even in its dormancy.
So pull on your warmest coat, gather your tools, and give your garden the winter care it deserves. Come spring, you’ll reap the rewards of these cold December days.
Further Reading: Mast Years: Why They Happen and Their Impact, RHS December Garden Jobs, RHS How to Plan a Border
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