Plant Protectors – How to Protect Plants From Frost and Snow
How to Protect Plants from Frost
Several decorative shrubs and perennials, while not hardy enough to withstand severe weather outdoors during the winter months unprotected, can be grown successfully if they are sheltered from extreme cold. Freezing or very cold winds cause the most damage.
The ideal situation for protecting plants — tender ones that is, and when you want to protect plants from frost — is on the south side of a wall or fence 1.8m (6ft) or more high. A dense evergreen hedge can also provide enough shelter. Plants that tolerate shade will usually be protected from the worst winds if planted among trees.
Shelter is not enough, however, during severe weather — further protection will be necessary. During a very cold spell, protect bushy shrubs by wrapping straw around the branches, binding it in place with sheets of hessian sacking, tied with twine.
You can protect plants from frost, such as wall shrubs and climbers, by mats made of straw sandwiched between two sheets of fine chicken wire. Simply squeeze a 10-12cm (4-5in) layer of material between two pieces of chicken wire, then join the edges by twisting the wires together. Hang the ‘mats’ in front of the plants in bad weather.
Free-standing shrubs — newly planted evergreens are especially at risk — can be protected during the winter by using a strip of the same construction. Stand it on end around the plant like a collar. During the coldest weather a lid of similar material can be put on top.
Bamboo canes and a polythene bag with the bottom slit open will also give a fair amount of protection. Insert four canes around the plant in a square. Lower the bag over the canes to cover the plant.
Protecting plants which produce new shoots from the base each year — tender herbaceous perennials, and certain shrubs such as—should have the crowns protected. Put a 15-23cm (6-9in) layer of mulch such as straw, weathered ashes, coarse sand or forest bark around and over the crown of the plants in late autumn Anchor this material with a few rocks or pieces of rubble if necessary. Clear away this layer in early spring.
An alternative for protecting plants is to use bamboo canes and straw. Form a wigwam of canes by inserting about six at equal distances around the plant and tying them together at the top. Also loop string halfway down each cane, all around the wigwam. Stuff straw or even crumpled newspaper into this framework and, if necessary, tie it with more string. Another method is to tie hessian around the wigwam.
For protecting plants in cold or exposed areas, do not cut down the dead top-growth of herbaceous perennials in the autumn Instead leave this tidying-up job until the spring — the old stems will afford some winter protection for the delicate dormant shoots in the crown. It is also a good idea to leave the dead-heading of susceptible shrubs such as hydrangeas until the spring, since the broad clusters of deadform a useful insulation layer and a sort of ‘umbrella’ against snow.
The best frost protection of all is to move tender plants under glass — into a greenhouse or cold frame. Plants which cannot be moved can be protected in situ by placing a glass or plastic cloche over them. Leave some ventilation and do not remove the cover too quickly when the weather turns milder — instead, increase the ventilation steadily over a few days to harden off the plants.
Often, the damaging effects of frosts are not so much caused by the low temperature as by the speed at which the frost melts when early morning sun strikes it. Camellias are notoriously susceptible to petal scorch within the unfurling flower buds in late winter when planted in a spot where morning sun falls on them. The best solution is to plant such species either in full shade or continuous dappled shade, or against a west-facing wall, where the rate of melting will be slower.
Surprisingly, a layer of ice over new shoots actually protects them against extreme cold, so if you find a prized tender shrub covered in thick white frost, a gentle spray with cold water before the sun strikes will reduce the chance of permanent damage. Never spray with warm or hot water, however.
If shrubs, trees or evergreen perennials do become damaged by cold or other weather conditions in winter, leave them alone until the spring when new growth starts to appear. Pruning in winter will often promote the premature emergence of tender growth which can then be damaged further by a late frost. If the plant looks dead right down to the ground, don’t despair — wait until the summer before you grub it out, since new growth may appear from ground level given time. The so-called hardy fuchsias, for instance, in’ variably die down to the ground every winter, but vigorous shoots burst out from the crown in spring. Trim off the dead wood as soon as new shoots appear.
Protection Against Snow
As with ice, snow can actually insulate tender plants against extreme cold — that is why many alpine plants are able to survive on even the coldest mountains. However, a heavy load of snow can cause physical damage to plants. The branches of evergreen trees and shrubs can be broken under the weight. Those branches which are weighed down but do not break may not resume their original position when the snow melts — this can ruin the shape of a compact, formal plant such as a dwarf or prostrate conifer.
If heavy snow is expected, bind the branches of evergreens with garden string or rope until all danger is past. If branches get weighed down before you have a chance to bind them, shake or brush loose snow away immediately and tie in the branches if further snow is expected or if the branches don’t fall back into place.
Gently brush snow off cloches, cold frames or greenhouse roofs, since a prolonged covering will reduce the light levels inside quite dramatically.