Crocus care tips for February
How to save winter-damaged plants
Don’t be in a hurry to discard winter-damaged plants, says Alan Titchmarsh, as he explains how to give them emergency care
After such a dry and frosty winter, gardeners have a little extra to think about. Winter losses due to excessive wet will be reduced, but the biting northerly winds that seem to have lasted throughout February will have taken their toll on inadequately protected plants. In my new Hampshire garden, the soil is considerably lighter than it was at Barleywood, and so the problems of plants rotting in winter wet will hopefully be much less of an issue. This year, my main worry will be water shortage, so I’m ordering extra mulch and taking steps to save water wherever I can.
Although severe cold is often blamed for the loss of plants in winter, the culprit is usually the combination of low temperatures coupled with chilling winds, especially with evergreens. Deciduous plants are at their most vulnerable during early winter before they are fully dormant, or after an unseasonably mild spell when they can be fooled into breaking dormancy too early. Excessively long periods of severe weather can also be very damaging. However, if you know what symptoms to look for and you spot the damage early, you can take remedial action to minimize the problem.
We’ve all experienced severe storms in recent years and are fully aware of the massive destruction they can cause. Only last month, my garden was blasted by storm-force gales which resulted in one or two evergreen shrubs leaning over at a precarious angle.
When high winds wreak havoc across the garden, it’s the new trees and shrubs that haven’t had sufficient time to take root that are the most vulnerable to damage. Unless securely staked and tied, they are easily rocked loose or even completely uprooted. Some trees and shrubs are vulnerable to strong winds even when well established. For example, poplars and willows tend to become top-heavy with a large framework of branches that acts like a sail in high winds, while birch trees can be weak at the base of the trunk and can be toppled in a severe storm. Some types of tree are also prone to damage where large limbs join the trunk. Any tree or shrub that has been weakened by a previous storms or pest and disease attack is even more susceptible.
Garden structures can also be damaged by high winds, so it is worth checking over fences, trellis, arches, pergolas and garden buildings to make sure they are secure. Consider fitting ground anchors and wind braces to greenhouses and sheds in exposed positions.
Uprooted trees and shrubs
Specimens uprooted by strong winds should be replanted immediately. If you can, erect a temporary windbreak made from special windbreak fabric held taut on stout posts firmly knocked into the ground. Plants that have been loosened by wind rock need to be refirmed into the soil and pruned back to reduce wind resistance or protected with a windbreak. Re-stake trees and secure them with good-quality tree ties, or provide added stability using guy ropes attached to the main branches and pegged into the ground on all sides.
Cut off broken branches neatly using a suitable sharp, clean-bladed tool. Always use the right tools: tackle stems up to 1cm thick (1/2in) with good-quality secateurs; 1-3cm (1/2-1 1/4in) using long-handled loppers; and stems over 3cm (1 1/4in) using a pruning saw. Always make sure the blades are sharp to make cuts without crushing or bruising the stems. If the branches are large or are not within easy reach, get professional help from a qualified tree surgeon.
All evergreens continue to lose water through their leaves throughout the winter. Wind increases this rate of transpiration, resulting in scorched foliage if the plant cannot take up sufficient water through its roots. This is particularly a problem when the ground is frozen, which prevents the plants from drawing moisture from the soil. In normal circumstances, evergreens exhibit various strategies to counter the problem, such as dropping needles or drooping leaves. However, in severe conditions this may not be sufficient. If possible, put up a windbreak to protect vulnerable plants or wrap them with fine-mesh netting during prolonged cold and windy spells. In spring, trim off brown foliage - cutting back to a fresh green leaf.
Frost can look beautiful in the winter garden, but may prove deadly to vulnerable plants. Non-hardy plants should always be protected during the coldest months either by moving them somewhere frost-free, or by protecting them in situ using blankets of leaves, garden fleece or other insulating material. Even fully hardy plants can be damaged by frost if followed by a rapid thaw, such as when exposed to early morning sun. Early flowering plants like camellias, magnolias, pieris and hydrangeas, as well as the blossoms on fruit trees, are particularly prone to damage. Where sub-zero temperatures are prolonged or very severe, even large well-established specimens can be adversely affected. Frost can lift the soil and loosen the roots, cause exposed stems to die back and even split the bark on the limbs and trunks of trees.
Remove damaged buds and flowers by hand or using secateurs to tidy the display. Next year, protect with garden fleece if a cold snap is forecast or consider moving the plant to a less exposed position. With new plantings, avoid east-facing walls. Those plants that are foolish enough to flower in winter can have their displays cut short by severe cold. Cut stems of scented witch hazel to enjoy indoors if a severe cold-snap is forecast when the blooms are opening. And cover the blooms of low-growing Christmas rose (Helleborus niger) and Algerian iris (Iris unguicularis) with a cloche to protect them from mud-splash in heavy rain.
Re-firm the soil around the roots of plants lifted by frost as soon as the ground has thawed. New additions are most likely to be affected, but it is worth casting your eye over all your plants once in a while. For example, in my garden turf that was laid a few weeks ago was lifted clear of the soil and may have dried out had we not trampled it back into place.
The bark on established fruit trees and some evergreen flowering shrubs, such as rhododendrons, are prone to splitting during rapid freezing and thawing. If you notice a specimen in your garden has been damaged in this way, don’t panic. The plant should heal naturally in time, but in the meantime you might like to help protect it during the coldest weather by wrapping the affected stem or trunk. It’s also worth painting wound sealant on cracked plum and cherry bark as well as new deep cracks found on other trees.
Many plants will show signs of dieback after a severe winter. The easiest time to check is in spring when new growth starts. However, some plants break into growth later than others, so to make sure the stem is really dead before you cut it back - scratch the bark off with your thumbnail. If the stem underneath is greenish it’s OK, if brown it’s a candidate for the chop. This is a particularly useful technique when pruning back the exuberant growth of climbers. The stems of deciduous plants, such as hardy fuchsias, may die back completely. But don’t be in a hurry to discard the plant, since it should re-grow from healthy buds lying protected underground. In future, ensure these buds do survive by making sure the roots are well insulated with a layer of leaves or compost in autumn.
Late frosts in spring can also be a problem with new growth. Evergreen climbers, such as the climbing hydrangea (Hydrangea petiolaris), can be vulnerable to scorching when they start to shoot again in spring. Protect with garden fleece if a cold snap threatens.
Rain and snow
Excessive rain and snow can both be a threat to the winter garden. Plants will literally ‘drown’ if the ground is flooded or waterlogged for a long period of time, and heavy snow will weigh down evergreens and other plants – breaking branches and destroying their natural shape. Although a common sight during my youth in Yorkshire, now that I live further south heavy snowfall has been a problem only a couple of times in the last ten years.
Most plants can cope for short spells in waterlogged soils, but roots will die if the wet conditions persist. Plants that need a well-drained spot, such as alpines, will turn brown and soggy in no time at all. If your garden is wet all year, grow plants that can thrive in these conditions, but if waterlogging is an occasional problem, consider growing the more susceptible plants in containers so they can be moved to safety in wet weather, or create raised beds in problem areas. The only long-term solution is to improve the drainage or move house!
Snow for a day or two is great for the kids and the plants don’t mind it too much. But heavy falls will pull plants out of shape and may accumulate in sufficient quantities to cause permanent damage. Plants with tiered branches or horizontal growth, such as cedars, are particularly at risk. Likewise, evergreens pruned into flat-topped hedges or other decorative shapes that tend to collect snow. I know it looks pretty, but the moment you’ve taken the snaps with your camera, carefully knock snow from the boughs of evergreens. Once the thaw comes the snow increases in weight, and that’s when the damage is done. The solution is simple, just shake vulnerable plants periodically or tap them with a stick to dislodge accumulations. You can also wrap upright conifers with fine mesh netting to prevent them being forced out of shape. Also bear in mind that heavy snow can damage fruit cages and other net structures unless you remove the top net each winter.
But don’t let all this talk of bad weather put you off. It’s always worth trying the odd experiment in the garden - taking a chance with a star plant that may, on the face of it, struggle to survive. After all, that odd exotic climber or tropical border plant may be the magical ingredient that turns your ordinary border into something special.