Oliver Pemberton
Read the forecast, then work backwards
British winters are rarely uniform. A sheltered Cornish garden may sail through until January without a hard frost, while an exposed spot in the Scottish Borders or the Yorkshire Dales can be caught out in late October. The trick is not to guess, but to watch your local forecast for that first clear, still night after a mild spell — the one where temperatures drop sharply under a cloudless sky and the windscreen needs scraping at seven in the morning.
Your soil, happily, is on your side. Ground that has been warmed all summer holds a surprising amount of heat, and it releases that warmth slowly through the first cold snaps. That means there is a window of a few weeks after growth stops but before the ground freezes when everything you do in the garden will have the greatest effect. Aim to have the main jobs finished by the end of November in most parts of the UK.
Mulch your borders properly
Mulching is the single most useful thing you can do for a mixed border before winter. A generous layer — around 5 to 7 centimetres of well-rotted manure, garden compost or bark chippings — acts as a blanket over the root zone, moderating the freeze-thaw cycle that heaves shallow-rooted plants out of the ground. It also feeds the soil life beneath, so worms and microbes keep working through the colder months.
The detail that matters most is where you stop. Pull the mulch back so it sits clear of stems, trunks and the crowns of herbaceous perennials. Piling it against the collar of a shrub traps damp against the bark and invites rot, which does far more damage than cold alone. A few rules of thumb:
- Mulch when the soil is damp but not waterlogged, and never over frozen ground.
- Leave a bare ring of soil around alpines, lavender, rosemary and other Mediterranean plants, which hate winter wet more than they hate cold.
- Keep mulch clear of the base of fruit trees and roses to avoid collar rot.
- Top up around newly planted hedging, but firm the plants in first if the frost has lifted them.
Wrap and shelter tender shrubs
Borderline plants are the ones that will let you down: tree ferns, cordylines, phormiums, olives, bay, citrus in pots. The aim is to keep the worst of the cold and, just as importantly, the wet off the growing points without sealing the plant into a sweaty plastic bag.
- Gather and tie the fronds of cordylines and phormiums upwards so water runs off the crown rather than sitting in it.
- Pack the crown of a tree fern with dry straw, then tie the fronds over the top like a tent.
- Wrap trunks and pots in hessian or horticultural fleece rather than plastic sheeting, which traps condensation and causes rot.
- Move pots of tender plants against a house wall, group them together for mutual shelter, and stand them on pot feet so drainage holes do not block.
- Lift dahlias after the first light frost blackens the foliage, dry the tubers upside down for a fortnight, then store them in barely damp compost in a frost-free shed.
Check wrappings every few weeks. If a mild, damp spell arrives, loosen things off for a day or two so air can circulate.
Look after containers, greenhouses and cold frames
Compost in a pot freezes far faster than soil in the ground, and when it freezes it expands — which is why terracotta cracks and why roots in small pots die. Reduce watering from October onwards, but do not let containers dry out completely, as parched roots are more vulnerable to cold. Raise pots onto feet or bricks to keep drainage holes clear of standing water.
Inside the greenhouse, bubble wrap insulation clipped to the glazing makes a real difference to overnight temperatures. Ventilate for an hour or two on mild, bright days to keep mould and damping-off at bay, and water sparingly in the morning rather than the evening. Cold frames should be closed at night and opened during the day, with a layer of fleece over anything delicate inside.
Clean, sharpen and store your tools
This is the job most of us skip, and it is the one that pays you back in spring. A winter's neglect is what turns a good pair of secateurs into a rusty, sticky mess.
- Scrape soil and sap off blades and handles, then dry everything thoroughly.
- Wipe metal parts with an oily rag or a little light oil to keep rust at bay.
- Sharpen secateurs, loppers, spades and hoes. Clean cuts heal faster and spread less disease.
- Sand wooden handles lightly and treat them with linseed oil.
- Store tools hanging, dry and off the floor, ideally in a shed with some ventilation.
While you are in the shed, drain hoses, lag outdoor taps and insulate water butts. A cracked tap in January is a miserable thing to discover.
Smallholding extras before the cold bites
If you keep a few acres, animals or an orchard, add these to the list. Bare-root trees, hedging whips and soft fruit can all go in now while they are dormant, giving roots time to settle before spring. Clear fallen leaves from around fruit trees to reduce the carry-over of disease, and mulch around the base without touching the trunk. Check water troughs daily once hard frosts start and break the ice morning and evening — livestock drink less in cold weather but still need a steady supply, and icy troughs are a common cause of trouble. Finally, make sure feed stores are dry and rodent-proof, and turn over any stored produce so a single rotting apple does not spoil the whole crate. A few focused days now, and you will walk into spring with healthy plants, sound tools and a garden already half a step ahead.
