Guide to Caring for Trees and Shrubs in Early Summer

Jobs to do

Trimming

The quick-growing, formal hedges should be clipped in early summer, if not done in late spring; they provide good, thick hedges, especially the evergreen ones, but they do need quite a lot of attention to maintain their precise shape.

The informal hedges which have finished flowering can now be trimmed also. However, trimming these is much more like pruning, in that flowered shoots are removed and the new growth thinned a little, if very crowded. If any of these hedges are formed of slow-growing plants, there is no need even to do this, simply cut off dead flower-heads.

Pinching

The removal of the tips of new shoots to just above the first leaf or pair of leaves is called ‘pinching’. It is done when the shoots are still young and soft and the tips can literally be pinched between the thumb and first finger nipping them off finally with the nails. It restricts the size of the plant and results in the growth of more side-shoots on the treated stem, so producing more flowers and leaves. Small, quick-growing shrubs, such as rock roses (cistus species), fuchsia, Jerusalem sage (Phlomis fruticosa) and young tree lupins benefit from this treatment. Pinching will also be required for wall-grown vines, removing the tip of a flowerless shoot just above the fourth leaf, and that of a sub-side-shoot above the first leaf. If a shoot has a flower cluster on it, stop it above the second leaf beyond the flowers.

Disbudding

Continue to disbud peaches, nectarines and vines.

If you are growing large-flowered or cluster-flowered roses for exhibition, the buds should be thinned during the next two or three weeks to leave only the central one at the end of each main stem.

Tying-in

Continue to tie-in the new shoots of fan-trained Morello cherries as they grow.

Deadheading

As in late spring, rhododendrons and azaleas can be dead-headed and tree lupins will exhaust themselves more quickly if allowed to form seed-pods. Kalmia and tree peony can be similarly treated.

Removal of unwanted shoots

This is not standard pruning, as it refers to the elimination of very specific growth. In the case of grafted or budded roses, it is the sucker growth from the rootstock which, if left on the plants, will rapidly and easily overcome the named variety. Suckers nearly always come up from soil level, near to a plant, and if the soil is dug away, it will be found growing from a root, usually close to the soil surface.

It should, ideally, be pulled off, to make sure that its point of origin is removed. You can cut it, but because its ‘roots’ remain, other suckers will sprout from the same point. Some rose stocks sucker particularly badly; those that are least troublesome are the Laxa stocks, said to be hybrid between Rosa alba and R. canina.

Don’t forget that standard roses are budded at the top of the main stem, so that the main stem is in fact stock and any buds on that which sprout, as well as any coming from the roots, are suckers and should be taken off. The leaflets on suckers are generally different in colour and size to those of the true variety.

Suckers on frame-work grafted fruit trees should also be removed; they will be any shoots not growing from the grafts and similarly may result in the tree returning to the original and now unwanted variety. Suckers from the roots of cherries, plums, peaches and all fruits associated with them, should also be dealt with.

Another kind of unwanted shoot is that which has plain green leaves, growing on a shrub or tree with variegated leaves. Sometimes shoots or branches will revert in this way, to the original species; they grow very strongly because they contain much more chlorophyll than the cream- or yellow-variegated form, and eventually take over the plant. Variegated forms are thought to be mutations in some cases, and are not always completely stable, but taking out these rogue shoots as soon as seen is usually sufficient.

Thinning

The wall fruits such as peaches, nectarines and apricots, and vine flower clusters may still need a little thinning if they are late varieties or if the season is cold. Vine fruits may already need thinning, if early. Apples and pears can be thinned, if they have set heavily, near the middle of early summer, before the ‘June drop’ takes place. Thin to leave about three or four fruits to a cluster, removing the centre or ‘king’ fruit first and then any which are small, damaged or misshapen. After the natural fall, remove any fruits in excess of one or two per cluster.

Watering

Continue to supply all wall-grown plants with water, especially fruit and remember, too, that wisteria and clematis are thirsty plants. If the weather is droughty, newly planted specimens of all kinds will be vulnerable and may even need their top growth sprayed every day as well, if they are evergreen.

Planning

Early summer is a good time to take stock of your rose display and decide whether, and if so where, it needs re-designing and improving. As the large-flowered and cluster-flowered climbers and old shrub roses come into flower, you will be able to see the best ‘doers’, the colour clashes and the weak or badly flowering varieties. By now, you will also be able to pick out the disease-prone kinds; unless you are very partial to them, they are not worth keeping, as they serve as centres of infection.

It is the best time, too, to visit rose nurseries and see how well their stocks are doing in the open, rather than on the bench at a show, where only the best will appear. A visit to your national rose society gardens during the next few weeks could be of great help in obtaining detailed cultural advice, ideas on design of rose gardens and use of roses in a garden, as well as information on new and particularly good varieties.

Increasing

From now until the end of summer it will be possible to take ‘soft’ tip cuttings of shrubs and climbers. Subjects which can be rooted from such cuttings include: deutzia, fuchsia, hydrangea, Jerusalem sage (phlomis), lavender, lavender cotton (santolina), rock rose (cistus), southernwood (artemisia) and spiraea. Rooting will be quicker if you can give them a little bottom heat, keeping the compost warm in some way. All can be rooted later in the summer from half-ripe cuttings.

All tip cuttings should be of the end 7.5cm (3in) or so of new shoots, without flower buds (otherwise they will not root), cut just above a leaf or pair of leaves. Two or three cuttings, stripped of their lowest leaves, are put into 9cm (3-1/2-in) pots, to half their length. Firm in and lightly water, then cover with blown-up polythene bags or put into a closed frame and keep warm and shaded until they root.

Many shrubs, trees and climbers which have flowered and set seed can be grown from seed sown now, in an outdoor nursery bed; some will need stratifying first. Once the seed has got to the stage when it can easily be detached from the plant, it is ready for sowing.

Grafts which were made in early spring may now have grown and taken so well that the wax is acting as a constriction. If it has not cracked, it would be best to remove it.

Treating pests and diseases

In addition to the troubles listed in Late Spring, there may be an infestation of codling moth caterpillars, which feed on the pips and the flesh at the centre of apples. Damage can be considerable and the only real answer is to spray; the birds do not seem to be able to get at the small caterpillars before they go into the fruit and other predatory insects appear to be non-existent.

Roses can still be infected by such plagues as black spot, mildew, greenfly, leaf-rolling sawfly grubs, leaf-cutting bees and chafer beetles. Scab, mildew, aphis, particularly woolly aphis (American blight) and canker, as well as codling moth, can infest fruit.

General work

The tasks are much what they were in the latter parts of spring. Continue to mow orchard swards, weed, blue hydrangeas, build the compost heap and support climbers as required.

30. August 2011 by admin
Categories: Trees and Shrubs | Tags: , | Comments Off on Guide to Caring for Trees and Shrubs in Early Summer

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