Gardeners with a penchant for tender plants have been reasonably lucky for the last few years. A succession of mild winters with little if any snow have meant that most tender plants have sailed through the cold season unscathed. Yet there’s always the risk that frost can bite when you least expect it.
1 Keep alpines dry
Growing at altitude in the wild, hardy alpine plants can shrug off frost and use a blanket of snow for insulation. Their real enemy in winter is heavy rain and boggy soil, which can make them rot. To keep them alive, protect them from rain by ensuring they’re planted in a well drained gritty soil and build them a small perspex shelter supported on columns of bricks, or use a plastic cloche with open ends so they can stay ventillated without getting their crowns wet.
2 Lift tender tubers
Plants such as dahlias, eucomis, begonias and gladioli have tender bulbs, tubers and corms that benefit from a deep mulch of compost topped with a layer of chipped bark in winter. In colder parts of the country it’s better to lift them before the frosts, shaking off any soil, cutting off the stems to 10cm (4in) and leaving them to dry for a couple of weeks. Then, store them in a frost-free place in a suitable plastic tray filled with compost.
3 Add a layer of fleece
Tender plants, rooted cuttings and young autumn crops can all be protected from frost, wind and hail by swaddling them with horticultural-grade fleece. This light weight and porous fabric allows the plants to receive the light, warmth and moisture they need to grow, but without making plants overheat or increasing humidity. Hold it in place using heavy stones or bricks, without dragging the plant down. Make a tent over taller plants using garden canes and pegs or clips.
4 Wrap up tender exotics
Tender exotic plants such as banana plants and tree ferns will die if exposed to freezing temperatures, so if you can’t pot them up and move them into a frost-free greenhouse or conservatory, it’s best to wrap them in a layer of fleece or hessian, with straw or polystyrene packed inside to protect their crowns. It’s best to get this protective layer in place by late autumn. During long period of warm weather the ‘duvet’ should be removed to prevent the plant from sweating and possibly rotting.
5 Protect patio pots with bubblewrap
Plants in containers are specially vulnerable to frost damage as their roots don’t enjoy as much insulation as they would if planted in the ground. Wrap the pots in a duvet of bubblewrap and hide it with a layer of hessian and twine for a more aesthetically pleasing look on the patio. Don’t forget that terracotta pots are porous, so ensure they stay well drained by setting them on pot feet.
6. Lay a mulch
Adding a thick 10cm (4in) mulch around the bottom of a shrub, or over the top of a dormant perennial plant underground, can insulate the soil and keep its roots, tubers, bulbs or corms from freezing. Useful organic mulches (which will rot down in time, adding nutrients to the soil) include bark, garden shreddings, compost, well-rotted manure, grass clippings, newspaper, leafmould and straw.
• Don’t feed plants with nitrogen-rich fertilisers late in the season as this encourages them to put on frost-vulnerable sappy growth
• Work out where your warm and sheltered spots are in the garden and group container plants in these positions over winter
• Plant early-flowering magnolias and camellias in a north or west-facing site so they’re protected from early morning sun on frosty days
• Invest in cloches and fleece for nights when frost or snow are forecast - all small plants will appreciate the extra insulation
• Knock snow off shrubs and hedges as the extra weight can snap branches