To prevent losses, have some horticultural fleece handy to protect the frost-sensitive wall shrubs such as camellias, passionflowers and solanums from Jack Frost’s icy fingers. To protect these and other vulnerable wall shrubs, simply fix a batten to the wall above the plant and suspend fleece or netting from it to hang down like a drape over the plant. Fixing a batten to the bottom of the drape will allow the covering to be rolled up in mild weather.
Camellias will loose their spring flower flowers and buds if planted on an east wall where the rising sun causes the dewy buds to freeze and drop off and the petals to turn brown
Wrap up with fleece
If you are only expecting a light freeze, you may be able to protect plants simply by covering them with a blanket of fleece – you can stop this blowing away by using clothes pegs to secure it to the leaves or branches. This acts like insulation, keeping warm air from the ground around the plant. The warmth may be enough to keep a plant from freezing during a short cold snap.
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Be sure to remove the fleece first thing in the morning after an overnight cold snap. If you don’t, condensation can build up and freeze again under the covering, which will damage the plant.
When wrapping plants for longer spells with fleece, make sure that the covers reach all the way to the root zone. Stake or tie it in place but resist the urge to bind the fleece tightly around the plant as doing this this can cause damage to the stems and foliage.
Protect frost-tender plants like bananas by surrounding plants, which have already had the frosted leaves cut back, with a cage made from chicken wire packed with straw or bracken then cover it with fleece to keep out wind. A hood of polystyrene can help keep rain out of the crown. Tree ferns can be similarly treated. Tie the fronds upright with straw or bracken packing at the centre, then wrap whole bundle in a double layer of horticultural fleece. The root area can be mulched to protect the roots from frost. Unwrap plants by May.
Fleece can also be double-layered for extra frost protection, and can be used beaneath cloches and in cold frames and greenhouses for extra insulation.
Mulch to protect roots
One of the easiest and most effective ways to protect sensitive border plants is by mulching. Organic mulches, which eventually decompose and release nutrients to the earth, are best. Put a deep layer of bark or well-rotted garden compost over the soil around the plants, spreading it out towards the drip line to protect surface roots. Always leave a 13mm space around the plant’s stem to allow air circulation and prevent rot.
Snow will insulate lavender plants but only if the ground hasn’t been frozen before the snow fall. The excessive weight of snow can damage plants and freeze the essential oil within the stem causing them die back. When snow and ice melts and soil becomes waterlogged this is when the trouble begins as these sensitive plants will inevitably die unless the soil is well draining
A layer of gravel around the crowns of silver-leaved plants such as lavender will help these vulnerable plants survive in cold, wet soil. You can also use twigs to make an open weave basket to cover and protect the crowns of vulnerable perennials such as penstemons and stuff the basket with dry straw or leaves. Alternatively use an empty wire hanging baskets held down with metal tent pegs to keep the plants snug in sub-zero temperatures.
Tricks and tips
Cordylines often die because their centres fill with water and become frozen. Protect these plants by drawing up the leaves and loosely tying them into an upright “column” with soft string. In severe weather wrap the sheaf of leaves with fleece, removing it as soon as conditions improve.
Use twine to tie up tall conifers too. Bring the limbs in closer to the trunk, so they don’t splay and break if snow builds up on them. Use stakes to prop up horizontal limbs on evergreen shrubs that might break if snow makes them too heavy. It’s advisable to go around the garden after a heavy snow fall with a long garden cane to tap the laden branches and ease their burden. Take note for the future, that pruning hedges so that they taper at the top will minimise snow damage.
Wrap the pots of container plants with bubble polythene and in freezing weather, temporarily cover the top growth with garden fleece. Better still, stand potted plants on trollies, so you can wheel them to a sheltered location or indoors when temperatures drop. Alternatively plunge (bury with the rim just showing) the pots into the ground.
Surrounded larger shrubs with an insulation jacket, which is made with a 5-7.5cm layer of bracken or straw sandwiched between sheets of wire netting. A detachable lid can be placed on top in very severe conditions. Alternatively, erect a wigwam of bamboo canes around the plant and pack around it with bracken or straw. Covering it with netting will keep everything in place.
Where possible, avoid walking on very wet soil, as it will harm the structure, which affects drainage and subsequently plant health as roots may drown or die through lack of oxygen. Repeatedly walking across a frozen lawn will leave black footprints when the ground eventually thaws.
One final thought, it might be good idea to water the veg plot (not the leaves or stems of the plants) before a big freeze beckons as it’s well known that wet soils prevent freeze injury to most plant roots! This is because it holds more heat than dry soil.
You will see on plant care labels there is a hardiness rating given for the plant. Take note of this before buying any outdoor plant, as this will give you a clear indication as to whether it will survive in your location. Some plants produce special hormones that keep them from freezing, and these plants have a lower hardiness rating (meaning they can survive colder weather) than plants which produce less of this hormone.
The RHS have devised the hardiness rating, which is divided into seven main categories ranging from H1 for glasshouse plants to H7 for plants that are fully hardy. Plants that are rated H5 are hardy in most areas of the UK even in the severest of winters. Plants that are growing in more exposed areas, and containerized plants however, may require protection and some evergreens may suffer foliage damage.
When buying new plants, find vulnerable ones a sheltered spot. Your garden will have warm spots, such as at the base of a south-facing wall, and cold or wet spots that are usually on the north side of the house. Site early flowering plants such camellias so that they are not exposed to the morning sun, as rapid thawing of frozen buds can result in blackening and bud drop.
Received wisdom says that pond owners should break a hole in the ice or float a large inflated ball in the water to allow oxygen to reach the water. However, research by conservation charity Pond Conservation has shown the opposite is true and oxygen levels can actually rise in a frozen-over pond, benefiting the animals and plants living beneath
Hanging a string of outdoor net lights over vulnerable shrubs can help keep them snug when temperatures take a nose dive.
When wind hits a solid barrier such as a brick wall or fence it tends to deflect upwards only to descend with greater turbulence on the other side. It’s a good idea therefore, to replace solid boundaries with ones that are permeable such as woven hurdles to avoid gusting winds and turbulence from damaging plants. Hedges, which are a magnet to wildlife, are a good alternative to fences as they deflect the wind upwards and over your garden, allowing less hardy plants to flourish in its lee. Living willow screens can also help to filter the wind, while creating an ornamental feature at the same time.