Shrub and Tree Garden Jobs for Early Spring

Jobs to do

Preparing the soil for planting

It is still not too late to plant the various kinds of shrubs and trees which would have been better put in during late autumn or early winter. If you are expecting an order to arrive from a nursery, have bought container-grown plants from a garden centre or have some plants heeled-in waiting for better weather, the soil can be prepared for these any time up to within a day or two of planting. Heavy soils may still be too wet for digging comfortably and any soil may be frozen, so always wait until it is possible to get a fork or a spade into it. If you find the soil difficult to penetrate, the plant roots will not find it easy either.

Planting

Once the dormant buds on woody plants begin to pop open and sprout stems and leaves, it is really too late for totally successful planting. As this will start happening shortly, you should plant roses, the hardy deciduous shrubs, including hedges and climbers, trees, vines and other fruit, as soon as possible. Towards the end of early spring is the time to plant many evergreens and a few of the hardiest grey-leaved shrubs, such as santolina and Senecio greyi. However, if there is some risk of a dry spring with strong cold winds, it would be better to wait until mid-spring or even early autumn, before planting these evergreens and evergreys.

Pruning

The groups of plants which need pruning at this season are the large-flowered and cluster-flowered (hybrid tea and floribunda) and climbing roses, the late-summer-flowering shrubs and winter-flowering shrubs and trees. If the fruit and summer-flowering clematis have not been finished (or even started), their pruning should be completed as soon in early spring as possible, particularly as clematis may already have new shoots up to 30cm (12in) long.

Roses

Early spring is generally accepted as the time to prune the most popular group of roses: the large-flowered and cluster-flowered modern bush types. Some gardeners start doing it in mid- or late winter because they maintain that flowering starts earlier as a result. However, as the tips of the shoots, pruned or unpruned, are likely to be damaged or killed by cold, later pruning, when one can see any damage, may mean less damage and only one lot of pruning.

Rose buds generally start to sprout towards the end of early spring, so pruning should be started at the beginning of the season. Large-flowered kinds need moderately hard cutting back to stimulate as many and as strong new shoots as possible. Weak, spindly shoots should be cut back flush with their parent stem; shoots growing into the centre or across the bush should also be removed, together with dead shoots.

The remaining healthy and vigorous shoots should then be pruned to remove about half to two-thirds their length; try to place each cut so that the bud immediately below it points outwards and the one below that, too, if possible. It is often the case that the dormant bud you assumed would sprout and grow outwards to form a perfect, goblet-shaped bush either dies, gets attacked, knocked off or otherwise assaulted and the one below it grows beautifully, straight into the centre.

The majority of large-flowered roses produce a good display and plenty of blooms for the house if pruned like this, but the tall-growing, vigorous kinds such as Queen Elizabeth and Peace need lighter cutting, otherwise they get taller at the expense of flowers. For best results only one-third of the main stem is cut off and lesser stems are merely tipped. Occasionally, one of the old main stems can be cut down to ground level to encourage new wood.

Cluster-flowered rose pruning is not so simple; with some varieties the recommendation to remove last year’s flowered stems can mean that virtually no growth is left above ground level. In order to produce the best show possible, pruning should ensure that the main stems are cut back to markedly differing lengths. For instance, those stems which are ‘middle-aged’ can be cut back moderately, to half to two-thirds their length, as the large-flowered kinds are. Any of last year’s shoots produced at or close to ground level should have only about one-third of their length removed and the oldest stems, perhaps one, two or three of them, should be pruned hard to leave 7.5 or 10cm (3 or 4in) only. Besides this, there is the routine pruning to remove weak, diseased, crowded or crossing shoots, if any remain.

By treating each main stem individually like this, and pruning to different lengths, it is possible to maintain a renewal of growth each year throughout the bush so that strong new shoots are constantly being encouraged, while older ones which are still capable of flowering are retained to ensure as good a display as possible. For the details of pruning climbing roses, see Late Winter.

The winter-flowering shrubs and trees include autumn-flowering cherry (Primus subhirtella autumnalis), Garrya elliptica, heather (Erica carnea in variety), laurustinus (Viburnum tinus), Mahonia Charity, sarcococca, Viburnum Dawn and V. faireri, winter sweet (Chimonanthus praecox) and witch hazel (Hamamelis mollis). All of these except the ericas need only a little pruning. Quite often you need not do any pruning at all if they are growing naturally into an attractive shape, and they will still flower perfectly well.

However, most shrubs have some dead shoots, broken branches, thin, spindly shoots shorter than the rest, or crowded together and crossing over. Cutting away this sort of growth, even if you do nothing else, will always ensure that the shrub grows more healthily and has better flowers and leaves. At the same time you can deal with the odd long stem which protrudes far beyond the main body of the bush; if it is as strong as that it will not flower well in any case, so it is better removed altogether, back to its point of origin. You can also cut back some of the oldest shoots, once the shrubs have been planted a few years, to just above a new or strong younger shoot.

A general rule when pruning flowering shrubs is to cut off the shoots which have had flowers on them, with the object of inducing the shrub to produce new shoots to take their place and flower the coming season. However, winter-flowering shrubs on the whole are rather slow-growing and such cutting-back is more likely to mutilate their appearance and discourage growth, rather than encourage it. So, on the whole, the rule is not to cut off old flowering growth unless it comes into any of the categories that have just been mentioned above.

Viburnum farreri and V. Dawn tend to be awkwardly shaped and often do need to have their figures improved; laurustinus turns itself into a nicely rounded bush without help. The autumn-flowering cherry may stick a stem straight up out of the otherwise weeping head; don’t hesitate to cut it right away, or the tree’s head will become more and more grossly unbalanced.

The mahonia will probably produce new shoots at or near ground level as the central stem extends; if the latter becomes too tall, it can be cut right down and the younger shoots allowed to grow into its place.

Erica carnea and its varieties are pruned quite differently; as soon as flowering is really finished, but before new growth starts, they may be not so much pruned as sheared. Trim them straight across with shears to cut off the dead flowers and shoots; this need only be done in alternate years.

Garrya elliptica can be pruned in this season; the remaining winter-flowering plants need not be pruned, except in occasional years in a general way.

The late-summer-flowering shrubs are generally considered to include those which flower in mid-summer, late summer and through early autumn into mid-autumn and pruning can be done towards the end of early spring or the beginning of mid-spring.

These shrubs generally flower on shoots produced earlier in the same season, ie., a new shoot which starts to grow in early or mid-spring will bear flowers some time during the later part of summer or in autumn of the same year. As it is a principle of growth that the removal of shoots from a plant results in the plant replacing them with new shoots, so pruning in spring will — or should — automatically ensure that it will have a new crop of blossom later on. Therefore, if you do not have time to prune this type of shrub in the early part of spring and decide to make up for lost time by doing it in early summer, you will remove most of the new growth and flowering display. Not only that: the plant will try to make good the loss by developing a new batch of shoots, but too late for them to ripen by the time winter comes, so that tips will be killed, the shoots die back and disease infect the dead growth. The result is a weakly growing, poorly flowering shrub which may never recover.

Cutting back hard

Old deciduous hedges which have got rather gaunt and bare at the base can still be cut back hard in early spring, down to half or even less, of their height. Sometimes better results are obtained doing it just before new growth starts, rather than at the beginning of the dormancy period. Furthermore, you can remove growth killed by the winter’s cold at the same time. Dormant buds, low down, will sprout as a result of the hard cutting.

If evergreen hedges are to be treated, early or, preferably, mid-spring is the time to cut them, but very hard cutting back is generally not advisable. The cypresses and brooms in particular object to this treatment and may die as a result. It is quite enough to remove about half the height of a hardy evergreen hedge and only about one-third of the sensitive ones. If the hedge has got too broad, as well as too high, wait until the second spring before cutting the sides, so that the vertical growth has a chance to grow and keep the hedge going while the sides recover from drastic trimming.

Informal flowering hedges which bloom from mid-summer onwards should be cut back now before growth really gets going. Cut last year’s flowered shoots off to leave stubs a few centimetres (inches) long, on which there are dormant buds. Slow-growing hedges of this kind need not be trimmed except to cut back long straggling shoots now.

Individual shrub specimens which have grown tall or rather old can be rejuvenated by hard cutting at this time; Buddleia davidii and varieties and the tall hypericums can be pruned to leave stubs at ground level late in early spring. Doing this every few years is an alternative to moderate pruning every year. Hippophae, too, can be cut down to about 90cm (36in). The older and hardier rhododendron hybrids and varieties will tolerate cutting back to about 60-90cm (24-36in).

There is another reason for hard cutting back in spring, if the shrubs concerned have attractively coloured bark. There are varieties of dogwood (cornus) and willow (salix) which have brilliantly red, orange or yellow bark on the young shoots. If such plants are cut down hard to leave about 15cm (6in) of stem, they will produce a great number of these young shoots; all or about half of last year’s shoots can be pruned, depending on how ruthless you feel.

Feeding

Roses can be given their first feed of the growing season as soon as pruning is finished. You can use one of the proprietary compound fertilizers, or a general one which is high in potash, to help with flowering. Summer-flowering shrubs and the later summer-flowering clematis can also be fed with similar fertilizers. If you still have shrubs or trees to put in, dress the site with bonemeal about a week before planting, forking it in evenly at about 120g per sq m (4oz per sq yd). Give hedges and shrubs which have been hard-pruned a dressing of a general compound fertilizer, forking or hoeing it in if practicable, or watering it in.

Pollinating

The only blossom likely to be out at this time of the year is that of peaches, nectarines and apricots. Such fruits are natives of much warmer climates than the temperate zone and so flower earlier, with the certainty of being pollinated by insects which also come out of their winter hibernation much earlier. Pollinators from temperate climates do not appear in large quantities until mid-spring, so you must help the process of fertilization with a child’s paint-brush, doing it preferably in the middle of a sunny day.

Protecting

The fruit and the shrubs which have had cover on them all winter to guard against bullfinches, sparrows and other birds nipping out the flower or fruit buds should be gone over carefully, as the birds can do a lot of damage now, at the end of winter. The forsythia and flowering cherry displays can be non-existent as a result of bud pecking, and sprays and protective webbing may need renewing.

Apricots, peaches and nectarines growing with wall protection may already be in flower, or just coming up to it, and if you want to be certain of a crop, you should insulate against frost and cold winds. A polythene net dropped in front of them from battens on the wall will do the job, or you can have a more elaborate arrangement with clear plastic sheeting. Remove it as soon as the temperature goes up, otherwise any pollinating insects about cannot do their work.

Treating pests and diseases

In early spring there is little more to do to woody plants than examine them to discover how they are. New growth will only just be starting to appear, so pests and diseases will not yet be visible in large quantities. Greenfly, of course, may start to hatch from their over-wintering eggs, in town gardens and others where the district is mild or the season an early one. The opening buds of roses, apples and pears are likely to be their main targets.

The fungus disease, scab, on apples and pears (a different strain on the latter) may start to infect leaves as they unfold, if temperature and humidity are high enough, but mid-spring is usually the season when it becomes really dangerous. Mildew may attack the new growth of roses, especially if it were present the previous year. Fruit can be infected by mildew and there are different mildews according to which fruit is being infected. However, they can all be treated with the same chemicals. If mildew does appear, it is worth removing the ailing growth now, cutting off the shoot well below the infection, even if it does mean removing apparently healthy growth.

The fungus disease on azaleas which makes the leaves become thick and curled up, with grey bloom on the surface, is called azalea gall; cutting off the affected parts is usually all that need be done. Gall does not appear on outdoor azaleas very much; the indoor potted types are more likely to get gall as it thrives in close, humid conditions.

General work

If it has not been done before, taking a good look round the plants is advisable, to discover broken branches, stakes which have been blown askew, loosened ties, trees which have been wind-rocked (so that a hollow full of water has formed round the base of the trunk), and freshly planted trees and shrubs which have been lifted out of the soil as a result of the action of frost. Any of these troubles left unrepaired will at best result in a damaged and weakened plant and at worst a dead one. Wind-rocking causes some of the most serious trouble, because the collected water starts a rot of the bark of the trunk. Once the bark has been killed all the way round, it is only a matter of time before the tree dies.

Check that protective coverings and barriers against cold are still intact and in place; although this is the beginning of the spring some of the coldest weather of the winter can occur during the next four or five weeks.

The main stems of grape vines, which were loosened and allowed partially to hang down in mid winter can now be tied back in position again.

Increasing

Early spring is the recommended season for grafting fruit trees. The grafting the gardener will most likely want to do will be the kind that changes the variety of a mature tree and this is most frequently done with apples and pears. By now the sap has begun to run again and the chance of the grafts ‘taking’ is much more certain than at any other season.

For grafting you will need a really sharp, straight-bladed, grafting knife (not an ordinary penknife and not one with a curved blade), grafting wax (proprietary hot and cold waxes can be bought from garden shops) and a brush; a rag always seems to be useful, too.

On a mature tree with a cup-shaped arrangement of main branches, the latter should be left to almost their complete length, so that the growth at the end of each is not less than two years old. The side-shoots and side branches should be cut back to about 20cm (8in) long.

The pattern of grafting should be herring-bone, so that the new branches come out alternately on each side of a main branch; any original side branches which do not fit into this pattern should be removed completely. So, too, should any main branches growing into the centre of the tree or straight upwards; if any are too close, now is the time to remove one here and there.

The secret of successful grafting is to get what are known as the cambium layers matching. The cambium is a layer of tissue composed of cells which divide and create new woody cells, just below the bark; in most plants the cambium is bright green, The sloping cuts made in both scion and stock expose as much of this layer as possible and so increase the chances of the graft being successful.

The scion is the new variety to be grafted on to the parent tree, or stock, and for the average bush apple or pear on dwarfing stock, about a hundred scions will be required. You should have already obtained them and they can now be cut so that they are about 10 buds long. For a stub graft, the end of the scion should be cut to form a short wedge. The side branch or side-shoot to be grafted has a sloping cut made partially through its upper side; this cut is pulled open and the scion pushed into it, matching the cut surfaces. Once the scion is in, the stub can be cut back to just above the graft and grafting wax painted completely over the whole stub and cut so that there are no gaps at all.

If there is no stub in a suitable position, a side-cleft grafting may be used instead. Cut the branch to be grafted to lift a tongue of bark and wood, cut the tip of the tongue off and push the scion in with the cut surfaces facing and matching. The end of the scion for this type of graft should have a single flat, tapered surface; finish by waxing, as before. The ends of the main branches should be stub grafted.

After grafting, as the tree begins to grow, sucker shoots will appear from trunk and main branches; these suckers should be removed while still only a few centimetres (inches) long.

Clematis can still be layered, but mid-spring will be too late so do it early in the season.

30. August 2011 by admin
Categories: Shrub and Tree Garden | Tags: , , , | Comments Off on Shrub and Tree Garden Jobs for Early Spring

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