UNIVERSITY OF B.C LIBBARY DUPL

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THE LIBRARY

THE UNIVERSITY OF BRITISH COLUMBIA

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FLOWERING TREES AND SHRUBS: A

Handbook for Gardeners

Digitized by tine Internet Arcinive

in 2010 witii funding from

University of Britisin Columbia Library

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Romneva Coulteri.

A HANDBOOK OF FLOWERING TREES

:: AND SHRUBS ::

FOR GARDENERS

BY R. C. NOTCUTT. EDITED BY THE LATE W. R. DYKES

LONDON: MARTIN HOPKINSON ^ COMPANY LTD : 14 HENRIETTA STREET, CO VENT GARDEN, W.C. 1926

Printed in Great Britain,

PREFACE

In the following pages I have endeavoured to describe some of the best known families of the hardy flowering shrubs, which are attracting so much attention from gardeners that they may well claim to be the most popular of all branches of gardening at the present time. I am sorry that owing to space I have had to omit many beautiful families, in particular the genera of Spiraea, Weigelia, Rhus, Philadelphus, and Lilac.

It is not surprising that the flowering shrub section of the garden should have this popularity, for it has the great advantage of being economical in labour and of providing an interest spread over the greater part of the year, firstly wdth the flowers, later on with the berries and fruit, and lastly in the gorgeous autumn colouring of the foliage.

In order that amateurs who are taking up this branch of horticulture may find my descriptions and notes helpful, I have considered the needs of the practical gardener as far as possible and have avoided the use of difficult botanical terms.

In all cases of naming I have followed the Kew Hand List. I have also often referred for guidance to Mr. W. J. Bean's " Trees and Shrubs, hardy in the British Isles," the most valuable book ever written on this class of plants and one which has done much to en- courage the culture of these shrubs and trees.

vi PREFACE

The names of certain shrubs have unfortunately been much confused, the same plant being known under two or more names, which is very misleading to the be- ginner. Take for example the common Lilac- Syringa vulgaris this is often ordered by the uninitiated with the idea of receiving, not a Lilac, but the old fashioned, sweet-scented Syringa (Philadelphus coronaria). I hope this book will help to prevent disappointment due to such mistakes.

Considerable space is devoted to the description and cultivation of plants that will thrive on the sea coast. This is a section of gardening in which a good deal of care (and experience) is necessary. There are many shrubs that grow and flourish inland which will be found entirely unsuitable for a seaside garden where they are exposed to strong salt winds from the sea. However, experience has shown that there are many beautiful shrubs that will resist these winds and indeed thrive better on the coast than further inland, where they are subjected to a mild, damp air during summer and autumn and far sharper frost in mid-winter and spring. This is largely accounted for by the plants forming hard, short growths which are fully ripened by the autumn sunshine thus enabling them to stand the cold of winter far better than more softly grown plants in districts inland.

Nothing is more disappointing than to spend time and money on plants only to find, after the first cold spring and when a whole year has been lost, that they are quite unsuitable for the place in which they have been planted.

PREFACE vii

I am greatly indebted to Mr. Collingwood Ingram for his chapter on Japanese Cherries, a group of plants which he has so carefully studied and cultivated. He is now looked to as the best authority on these delight- ful spring-flowering shrubs. I am also much indebted to Mr. Osbom of Kew, Mr. Gould of Wisley, and to my nursery foreman, Mr. E. Thatcher, all of whom, with their long practical experience, have been of the greatest help. Lastly I am deeply grateful to the late Mr. W. R. Dykes, whose tragic death occurred as a result of a motor accident just as we were completing the last few pages. I shall always bear a debt of gratitude to his memory as without his help I should never have attempted this work.

R. C. NOTCUTT.

WOODBRIDGE,

May, 1926.

CONTENTS

PAGE

Chapter I.

Introduction .

I

II.

Berberis

21

, III.

BUDDLEIAS

51

, IV.

Ceanothus

57

V.

CiSTUS AND HeLIANTHEMUMS

65

, VI.

COTONEASTERS .

82

, VII.

Cytisus and Genista .

102

, VIII.

Prunus .

124

, IX.

Flowering Cherries .

135

X.

Pyracantha

156

, XL

Pyrus . . . .

161

, XII.

Viburnums

172

, XIII.

Seaside Plants

192

Ini

DEX

.

243

LIST OF ILLUSTRATIONS

I.

2.

3- 4- 5- 6.

7- 8.

9-

10.

II.

12.

13-

14.

15- 16.

17-

18. 19. 20. 21. 22.

23-

24.

Romneya Coulteri

Berberis polyantha

Berberis pniinosa

Berberis nibrostilla

Buddleia altemifolia

Buddleia variabilis magnifica

Ceanothus papillosus

Helianthemum algarvense

Cotoneaster frigida in flower

Cotoneaster frigida in berry

Spartium junceum

Pninus cerasifera Blireiana

Prunus persica, var. Clara Meyer

Prunus serrulata " Ojochin," syn. Senriko

Prunus spinosa, var. purpurea

Prunus subhirtella autumnalis

Pyrus Eleyi in fruit .

Viburnum Carlesii

Viburnum rhytidophyllum

Viburnum plicatum

Abutilon vitifolium

Cupressus macrocarpa :

Tree twenty years after planting .

Hedge three seasons after planting Escallonia Donard seedling Senecio Greyi ....

Frontispiece

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235

Flowering Shrubs

PLANTING, PRUNING, GENERAL TREATMENT AND PROPAGATING.

Within the last fifty years the planting of our gardens has undergone many changes. During the period from 1830 to 1880 the gardener's choice of shrubs was limited to such evergreens as Laurels, Aucubas and Holhes, mostly clipped into tight balls and thus losing all their natural grace. Conifers were also very popular and these with neat rows of scarlet Geraniums, yellow Calceolarias and blue Lobelias made the perfect garden of the mid- Victorian era.

With the increase of gardening periodicals and the publication in 1883 of W. Robinson's book, " The English Flower Garden," a change began. The first result was that much more interest was taken in her- baceous plants, and roses became more popular. It became fashionable to have beds of roses, each of one variety, and such beds became more and more usual at the expense of carpet and formal bedding. Towards the end of the nineteenth century and at the beginning of the twentieth, flowering shrubs also began to gain in popularity, and since the war this has been still more

2 FLOWERING SHRUBS

marked. It may be explained by two facts. In the first place they are both beautiful and interesting and secondly they are easy to cultivate. Once shrubs have been properly planted the cost of upkeep is small com- pared with that of plants which must be housed in the winter in heated greenhouses. In fact, a garden of flowering shrubs goes a long way towards solving the labour difficulty. Moreover in recent years there has been an immense increase in the number of new kinds of flowering shrubs available and the majority of them have been introduced as the result of the journeys of E. H. Wilson, George Forrest, and the late Reginald Farrer. These collectors have penetrated into vast unknown regions in China, Japan and Tibet, where the winters are as cold as our own, so that the majority of these new comers have quickly adapted themselves to our fickle climate, though some would doubtless flower better than they do if our summers were as hot as those which ripen their growth in their native homes.

Some of these recent introductions are already so well known that it is difficult to realize that some fifteen or twenty years ago the beautiful Viburnum Carlesii, with its fragrant white blossom, and the majestic purple spikes of the Buddleias were unknown. Perhaps the finest of all are the members of the new race of deciduous Berberis, gorgeous with their brilliant autumn foliage and sprays of coral-red fruit. In the Royal Horticultural Society's gardens at Wisley they are to be seen growing to perfection in the light, sandy soil and the masses of berries provide a wealth of colour in autumn, unsurpassed by any other genus.

GENERAL TREATMENT 3

Recent years have also seen many additions to the list of Brooms. The showy Cytisus Andreanus was rarely seen before 1870 and this has since been followed by Cytisus kewensis, with its cascades of creamy white flowers and still more recently by the delightful Cornish seedling, known as Cornish Cream.

Fortunately it is not only shrubs that flower in spring and summer that have been introduced recently to our gardens but such good things as Viburnum fragrans with its sweet-scented blossoms in mid-winter and Prunus subhirtella autumnalis, which sends forth its little, blush-white, scented flowers in profusion throughout November and December.

After these come the early spring flowering shrubs such as the double pink Cherries of Japan, with their bronzy foliage adding to the delight of the flowers and the form of Purple Plum, Prunus Blirieana, similar in its bronze foliage to P. cerasifera var. Pissardii, which is covered in spring with the most attractive salmon- pink blossoms. Such flowers are always doubly wel- come, coming as they do when the bleak, dreary days of winter are past and when there is a promise of better days to come. Among the Crab Apples (Pyrus) there have been in recent years many acquisitions, Pyrus Eleyi being the most striking of all, for, in addition to the deep red flowers and dark foliage, the red Cherry- like fruits are most attractive in early autumn.

These can be grown in bush form, but are most effective as standards. These Cherries and Crabs seldom become really large trees, but, if grouped amongst flowering bushes, or grown as single specimens

4 FLOWERING SHRUBS

they are seen to great advantage, especially if they are so planted that their flowers are seen against a dark background.

Another interesting family of Chinese plants com- prises the many species of Cotoneaster, which deserve to be even more widely planted than they are. Many are brilliant with scarlet berries in autumn and, if sprayed with quassia, to make them distasteful to birds, will continue to give a blaze of colour far into the winter.

While explorers of the borders of China and Tibet have been busily introducing to our gardens some of the seemingly inexhaustible botanical treasure of that region, hybridizers have not been idle. Foremost among them we must place Lemoine of Nancy, who will always be remembered for the many varieties of Lilac, Philadelphus and Weigelia, which he has intro- duced into commerce. All are hardy and the majority of them are easy to cultivate, while those in whose garden the soil is free from lime have also at their disposal the innumerable Rhododendron species and hybrids, which have been either introduced from China or raised from crosses made in this country.

Preparation of the Ground and Planting.

As flowering shrubs should be permanent when once planted, it is most essential that the ground should be properly prepared beforehand.

Time and money spent in proper preparation are true economy in the long run. The shrubs grow more vigorously and the colour of their foliage is richer when

GENERAL TREATMENT 5

they are planted on deeply cultivated soil than when they are forced into small holes in hard ground. It is frequently found that under a few inches of top culti- vated soil there exists a pan or hard layer, often only a few inches in thickness, but occasionally as much as a foot or more. Below this pan the ground generally becomes soft again but, imtil this hard layer is thor- oughly broken up, no trees will grow freely. The best possible preparation is to have all the ground intended for planting double-dug to the depth of 18 or 24 inches by the process known as " bastard trenching." This is cheaper in labour and on poor land often preferable to trenching. Bastard trenching is carried out in the following way. The piece of ground is first divided lengthwise into two and a trench two or three feet wide and one spit deep is opened across the end of one half. The soil removed is placed at the end of the other half as this is much less laborious than wheeling it away to the far end of the piece of ground. The bottom of the trench is then thoroughly dug and deeply broken up, after which it is covered by the soil thrown out of the next trench. The work proceeds up one side of the piece of ground and down the other side to the end at which it started, where the last trench is filled in with the soil thrown out of the first.

Each trench should be of the same width and it is best to mark them out with a line so as to keep the work straight and regular. If the ground is covered with grass, the sods should be skimmed off about tw^o inches thick and placed upside down on the lower spit in each trench before the top spit is thrown upon them.

6 FLOWERING SHRUBS

Ground thus treated allows surface water to drain away more readily and at the same time retains more moisture in dry weather than hard ground. Plants are thus enabled to withstand drought far better than when planted in unbroken ground or in soil of which only the top few inches have been dug.

In dealing with poor, or perhaps with almost any land it is most desirable that some form of stable or good farmyard manure should be added, and well mixed in while the digging is in progress. This is cer- tainly the best time for manuring, for, although manure can be dug in after planting with good results, there is never quite the same opportunity as during the process of digging.

Again, this manure has a double purpose ; it forms a store of food and nourishment for the plant and also holds a store of moisture, which is the salvation of many freshly-planted shrubs, through a spell of drought in the early summer.

In the same way a light mulch of stable manure on the surface close round the young shrubs is an immense help. The winter rains wash in the goodness of the manure, which also tends to prevent severe frost from penetrating down to the roots, and to keep the roots moist during a dry spell. Unfortunately in these days it is becoming increasingly difficult to obtain good manure at a reasonable price.

In dealing with heavy clay land, leaf mould, not too much decayed, is very valuable. It is also an admirable mulch but on light, dry soil nothing realty takes the place of farmyard manure.

GENERAL TREATMENT 7

Chemical manures are sometimes recommended, but they should be applied cautiously when dealing with transplanted shrubs and should never be used in hot, dry weather. Bone meal or flour is one of the best forms and gives good results. It acts slowly but the tree feels the benefit for a long time.

Deep planting should be avoided. It is usually quite easy to see the mark on the stems of the trees and shrubs which shows the depth at which they have previously been planted and this mark should be at the ground level when the trees are replanted. When trees are planted too deeply, with the mistaken idea of avoiding the trouble of staking, the obvious effect is that the roots fail to get the requisite air and warmth. They remain in the cold subsoil in the spring, whereas, if planted at the right depth, they get a certain amount of warmth from the sun which encourages good root action.

All shrubs should be firmly planted, the ground being well trodden down round the stem. If the plants are tall and likely to blow about in a high wind, it is neces- sary to stake them. In staking, always tie firmly so that the shrub and stake rock together without chafing. In many cases stakes are only required for a few months. If it is found necessary to leave them longer, the string should be cut and re-tied, at least once a year. Soft tarred cord, about as thick as a pencil, is the best tying material, with a piece of sacking wrapped firmly round the stem of the tree so as to avoid cutting into the bark. Nothing is worse than allowing freshly planted trees to sway about in the wind, thus forming a hoUow in the

8 FLOWERING SHRUBS

earth around the stem, which prevents the plant from forming fresh roots as quickly as it otherwise would. If a space should be noticed round the stem, the soil should at once be filled in and made firm.

Time for Transplanting.

Speaking generally, deciduous trees and shrubs may be safely moved at any time between the middle of October and the middle of March preferably during November and the first half of December. In average seasons there is a danger of severe frost and snow from Christmas till the middle of February. Trees and shrubs should not be transplanted when the ground is excessively wet and cold. If they arrive from a nursery when the ground is frozen, the bundles should not be opened so as to expose the roots to the frost. The best plan is to lay the roots in soil in a shed or in some sheltered place until the ground has thawed and planting is once more possible.

In the case of Evergreens, the transplanting season is longer, although mid-winter should be even more strictly avoided than in the case of deciduous plants. The period from the beginning of October to the middle of November is an excellent time for the work and so is April when the ground is warmer. In some instances the time may be extended to the middle of May.

It is now becoming a general practice in most nur- series to keep in pots many plants that are difficult to transplant. All varieties of Ceanothus and Cistus, and the Brooms should always be obtained in this way. In dealing with pot plants it is most essential that they

GROUPING 9

should not be dry when planted out. This particu- larly applies to plants that have been received from a distance. If the plants are dry when they are received, soak them in a pail of water before placing them in the ground. If planted with the roots really dry, no amount of watering afterwards will penetrate the ball. This is often the cause of failure, and the nurseryman is blamed, though the fault is the planter's.

Grouping.

There are many ways of planting flowering shrubs. Grouped in a broad border, five or seven being placed together and with a fair amount of room left for de- velopment, they display themselves well, and a few flowering standards placed singly here and there will produce a pleasing effect. This massing is more ad- vantageous than the old way of using single plants, one here and another of the same variety a little further on. Even rows should also be avoided. It is a difficult matter to give a regular distance for planting apart, but six feet is a fair average, while the small groups in the front should not be more than four feet from plant to plant, that is, when dealing with the smaller Berberis, Brooms, Cistus, etc. Again, a strong plant like a Buddleia will soon cover an area 8 or lo feet in diameter. When shrubs are planted to form a screen it is always well to use a fair proportion of evergreens, though the result will be less dull or monotonous if some of the more brilliant deciduous species are placed among them.

Many plants seem to thrive best when planted some-

10 FLOWERING SHRUBS

what thickly, but they require watching, and thinning must not be delayed too long. It is an excellent plan when arranging plants to have a bundle of cheap plants like Oval Leaf Privet, Berberis, Cotoneaster Simonsi, etc., which may be used as nurses, just to fill up the spaces between the choicer shrubs and to be cut out when the choicer specimens require more room.

Treatment after Planting.

Once the shrubs are planted and staked, where necessary, the after cultivation is comparatively simple. The main point is to keep the land stirred and free from all weeds either by hoeing or by occasional light forking. In this way the air penetrates into the soil and enables the young trees to withstand drought and greatly encourages growth.

If two pieces of ground were planted in the same way, one being left without weeding or hoeing and the other kept clean and the soil stirred, the difference in growth at the end of two years would be astonishing.

During the winter the land occupied by shrubs should be carefully forked over so as not to damage the small fibrous roots by digging too closely to the stems. This is all that is necessary until the surface begins to dry in the spring, when the hoe must again be brought into use.

Watering.

This is a vexed question, many successful cultivators of shrubs declaring it to be quite unnecessary, if the ground is properly cultivated. However, in some soils

WATERING II

and in some seasons watering is sometimes necessar^^ It is quite true that once shrubs are well established watering is seldom required. With freshly planted shrubs and particularly with evergreens, however, a good soaking or two in early summer often saves the life of a valuable plant. In late spring watering is most essential if the weather should set in hot and dry, and again when the plants have been turned out of pots, an occasional watering is most desirable.

It is always better to give a good soaking once a week than a little water each day. Make a slightly raised ring of soil about a foot or two from the stem of the plant so as to form a basin holding several gallons and the effect of the watering will last for days, es- pecially if the surface of the soil is kept loose and not allowed to form a hard crust. An excellent practice, particularly with evergreens, is to syringe or sprinkle overhead from a watering pot with a fine rose each afternoon an hour or two before sunset. This has the effect of freshening up the foliage after a hot, dry day and helps to encourage growth. Where possible rain water which has stood in the open air should be used in preference to that from underground mains, which is usually much colder than the atmosphere.

Pruning.

Some shrubs need little pruning and others need practically no pruning at all and yet sooner or later if they are to be kept within bounds and if they are not to become mere tangles of dead and living branches, the time will come when some pruning has to be done.

12 FLOWERING SHRUBS

An understanding of the principles of pruning is therefore a necessity if a collection of flowering shrubs is to be maintained in the best possible condition.

One of the worst offenders against all the rules of pruning is probably the jobbing gardener, whose one idea is to take a pair of garden shears and clip all shrubs back indiscriminately at sometime during the winter into tight spheres or square blocks. Imagine the result on the beautiful Pyrus (purpurea), which flowers from spurs on the old wood but more freely all along the slender branches of the new wood. A shear- ing in winter will remove practically all the flowering wood and a little observation and thought would show that this tree must be pruned immediately after the flowers fade, so that it has time during the rest of the year to produce and mature new growths which will flower in the following season.

Successful pruning is, in fact, largely a matter of observation and common sense. It will be found, however, that most flowering shrubs fall into one or other of the three following classes :

1. Those that flower early, in April and May, on the growths formed during the previous year. These should be pruned hard back immediately they have finished flowering and they will then produce and mature flowering branches for the following year. Examples of this class are Ribes, Cytisus, some Spiraeas, Berberis stenophylla, Ceanothus dentatus, C. Veit- chianus, C. papillosus, Pyrus floribunda, etc.

2. Those that flower a little later in May and June on the growth formed during the previous year. If

PRUNING 13

the pruning of these shrubs is postponed till the flowering is over, it will probably be found that if an attempt is made to cut out the old wood much young growth will be removed with it. If, on the other hand, these shrubs are left unpruned, they will be found to make more growth than will ripen and flower to ad- vantage and the best treatment is therefore to cut out the oldest shoots from the base in early spring. Then strong new shoots will develop and bear flowers in the following year. It might be thought that the priming of shrubs of this class should be carried out by re- moving all the oldest shoots immediately they have flowered. Some may, with advantage, be removed then, but if the pruning is very drastic and dry, hot weather follows little new growth may be formed for the next year. It is better therefore to leave most of the pruning until the spring. Examples of this class are Deutzias, Weigelias, Philadelphus, and such Berberis as B. Wilsonae, B. aggregata and others, which are specially valuable for their berries in the autumn.

3. Those that flower in summer or early autumn, generally at the tips of the young shoots produced during the current season. These should be pruned hard back during March, the growths of the previous season being cut back to within an inch or two of the old wood. The pruning must not go beyond this point, for it is dangerous to the life of the shrub to cut it back into the old hard wood unless there is a promising shoot or bud below the cut. To this class belong the Gloire de Versailles group of Ceanothus, Cytisus nigri-

14 FLOWERING SHRUBS

cans, Hydrangea paniculata, as well as many of the Buddleias and Spiraeas.

It follows, therefore, that the greatest care must be taken to ascertain and remember which shrubs flower on the wood of the previous year and which from the tips of the current season's growth. It must be re- membered too that all the species of a genus do not necessarily behave in the same way. Thus Tamarix hispida flowers in August and, if it is cut back hard in March, it produces fine panicles of flowers in the summer. Tamarix tetrandra, however, flowers during early June on the wood of the previous season and should therefore be pruned according to the directions given for dealing with shrubs belonging to the second group.

Again, Ceanothus Veitchianus and its allies should be pruned immediately after flowering at the end of May, whereas C. azureus and the other members of its group which flower from July onwards at the tips of the new growths, should be pruned in March.

Young standard trees need careful treatment in their early years but, once a shapely frame-work has been obtained, little pruning will be required except to cut away any thin, weakly branches and those which crowd the centre of the tree by growing across it.

Propagation.

There are four ways of propagating shrubs, by cuttings, by seeds, by layering, and by grafting or budding ; of these four systems the first two are by far the simplest.

PROPAGATION 15

The method of increasing plants by cuttings has been practised from the very earhest times. The ancient Greeks, indeed, seem to have been fully alive to this method of increasing plants, for the following is a note quoted from the " Legacy of Greece," the work of a Greek writer about 380 B.C. :

" As regards plants generated from cuttings . . .

that part of a branch where it was cut from a tree

is placed in the earth and there rootlets are sent

out. This is how it happens. The part of the

plant within the soil draws up juices, swells, and

developes a pneuma. The pneuma and the juices

concentrate the power of the plant below so that

it becomes denser. Then the lower end erupts

and gives forth tender roots."

Until quite recent times propagating by cuttings

seems to have gone on much as the old Greek describes.

Of late years, however, owing to the very careful and

thorough work at the Botanic Gardens, Edinburgh,

many new ways have been most successfully worked

out.

For the actual striking of the cuttings the most approved method is in a frame or greenhouse with slight bottom heat. The great secret of successful propagation is a close, saturated atmosphere which prevents excessive loss of moisture in a greenhouse, the best method is to erect inside it some small frames which can be kept closed.

In some cases it will be found that a swelling or callus forms at the base of the cutting but that no roots are emitted. It was found at Edinburgh that, if the callus

i6 FLOWERING SHRUBS

was pared away with a sharp knife, roots then began to grow. In some cases it was even necessar}^ to pare away the callus a second time in order to induce the cutting to root.

At Edinburgh cuttings are most successfully rooted in a practically cold frame in saturated sand, the cuttings being simply pressed into the sand without even the use of a dibber. Once rooted they must be removed to a light, sandy soil and no harm is apparently done, if they are frequently examined, so that they may be potted as soon as roots are being freely formed. The same method should be equally successful in the South, though there seems to be something in the northern climate which is eminently suitable for propagating.

Preparing the Cuttings.

Generally speaking small cuttings about two or three inches long are the best. In the majorit}^ of cases these should be made of the young shoots of the current year. Those made of half-ripe wood from mid-summer onwards should be cut off immediately below a leaf, or pair of leaves, so that the leaf -joint or node forms the base of the cutting, avoiding sappy or soft growths. At Edinburgh cuttings are taken under a joint or node (except in the case of Clematis) and all the leaves are left on the shoot, contrary to the usual wa}^ of pulling off the first two pairs. The idea which underlies this practice is that the plant will throw off the leaves at the base when it has no more use for them, and that, imtil it is ready to throw them off, they can help in the life of the plant.

PROPAGATION 17

Another excellent plan is to detach the cutting from the parent plant with a thin layer of old wood forming the base or heel. This particularty applies to Brooms, Ceanothus, and hard wooded plants. The cuttings should then be dibbled into the frame itself, boxes or pots. They root quicker when placed close to the edge of the pots. There is an advantage in pots as they can be lifted out of the frame immediately the cuttings are rooted.

Soil.

The soil in which cuttings are to be struck should be light and should contain a large percentage of sharp sand and have a further layer of sand on the surface. In the case of many of the hard wooded plants, sand alone, without any soil, may be used with good results.

If pots are used fill them one-third full of crocks, then add the soil, pressing it down gently but not too hard.

When only a cloche or hand-light is available the same sandy soil is desirable and it is astonishing what can be rooted in this simple way. They should be kept absolutely close no air admitted— for the first month or two. When signs of growth are seen admit air gradually until the cuttings will stand it without flagging. They wiU soon stand without any covering and after a time can be potted up or planted out in a sheltered bed.

Layering.

This is a simple way of propagating that rarely fails, though the time which is required varies a good deal from one to three years.

i8 FLOWERING SHRUBS

It is useful where only a small number of plants are wanted. The actual layering consists in fixing a branch firmly in the ground with a peg, covering the portion of the stem where the roots are wanted with three or four inches of soil. It is important that the flow of sap should be checked in the branch to be layered. This ma}^ be done in several ways, by cutting a slanting cut or a notch on the underside of the branch, by twisting the stem so that the bark splits, or by binding a piece of wire tightly round it. These are all methods which have proved satisfactory and it is found that roots tend to form more rapidly at the point where the flow of the sap is checked.

It is advisable to use some light soil containing sand or grit for covering the layers for this encourages the emission of roots. They should also be staked so as to keep them firm until they are rooted. This is all that is necessary till the branch begins to grow when it may be cut off from the parent plant.

Budding and Grafting.

This is such a technical process that it is not proposed to go into it in any detail. Nearly all flowering shrubs are far better when they can be obtained and grown on their own roots.

Grafting is carried out in the spring while budding must be done in the summer. The latter is the easier method and takes less time than the former.

Many of the choice Brooms, which do not come true from seed, must be grafted in the spring, in gentle heat, using either common Broom or Laburnum for the

PROPAGATION 19

stock. The choicer kinds of flowering trees and shrubs, such as many Cherries, and varieties of Pyrus and Prunus are generally either grafted or budded. The finer varieties of Lilac are often budded on the common Lilac, which is a far better stock than the Privet, but even then a careful watch must be kept for suckers.

Seed.

Raising plants from seed is perhaps the most satis- factory method of propagation. A great advantage of this method is that the plants are generally more vigorous. It has also been the method by which many new species have been raised in this country from seeds sent home from China, Tibet, and other parts of Asia. Owing to the length of the journey and to extreme climatic changes it is almost impossible to import living plants. Even if this were possible, seeds are so much more easily transported that they would be preferred.

Except perhaps in dealing with important seeds of wild species, there is always the chance that in raising seedlings we may find among them hybrids or unex- pected variations and herein lies one of the fascinations of seed raising.

When sowing seeds of shrubs it is preferable to use pots, pans, or boxes rather than to attempt to raise them in the open. The early spring is the best time for sowing seeds of shrubs but on no account should they be kept longer than is necessary before sowing, and, if they appear ripe in early autumn, they are best in the ground.

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The following points may be of some assistance in obtaining satisfactory germination. Seeds can be raised more quickly with slight bottom heat, 60° F to 70° F being a suitable temperature. Secondly they must be kept moist for moisture is needed by the seed in one of the first processes of germination, during which the absorption of water by the seed causes it to swell. Then activity occurs in the root tip, which is the first part of the seed to emerge out of its coat. Thirdly the soil should be similar to that recommended for cuttings but with not quite so much sand. Good drainage is equally necessary and the pots should be filled to one third or half their depth with crocks. Above this should come a layer of fibrous soil and finally finely sifted soil, slightly pressed down so that it is fairly firm. Large seeds may be covered to their own depth with sand or fine soil, but smaller seed need a thinner covering till finally with the smallest of all, such as Rhododendrons it is best to sow on the surface. Some growers find it better to sow large seeds in rather coarse loose soil containing a good pro- portion of sifted leaf soil. This has the advantage that the soil is well aerated a condition which tends to assist germination. When the surface is covered with very fine soil, it must be kept constantly moist or it will soon dry into a hard crust.

II.

BERBERIS (BARBERRY).

Among the many groups of hardy shrubs few can claim as many attractive quahties as the genus Berberis. Few genera include, as does that of the Berberis, both deciduous and evergreen species, valuable in spring for their flowers and in autumn for their tinted foliage, and, in many cases, for the wealth of brilliant fruits ranging in colour from the bluish-white of B. pruinosa through all the shades of pink, scarlet and crimson to rich purplish-black. This genus includes about one hundred and fifty species, many of them variable, and a great number of extremely beautiful hybrids which, while bewildering to the botanist, cannot fail to be a source of pleasure to the garden lover.

The many species of Berberis in cultivation have come to us from Europe, America, N. Africa, and Asia. Moreover, seeds recently collected in China have fur- nished us with many more good garden plants, which, although as yet not widely grown, are rapidly gaining a well-merited popularity.

Botanically the Barberries are not without interest. They are, for the most part, spiny shrubs remarkable for their yellow wood, the colouring matter of which has been used as a dye. Their flowers are yellow, with their parts in threes and consist of six or nine sepals.

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six petals, each of which usually bears two small glands at the base, and six stamens. The small greenish ovary ripens into an oval or rounded berry containing one or several seeds. The stamens possess a peculiar irrita- bility. In the newly-opened flower they lie within the concave petals ; but if the base of one of the filaments be touched with the point of a pin the stamen moves forward to the centre of the flower, striking its anther on the stigma. It is probable that this power of move- ment helps to ensure cross-pollination, for an insect visiting the honey-secreting glands at the base of the petals can hardly attain its goal without disturbing the stamens which close inwards and leave on its body pollen to be carried to another flower.

The spines of the Barberry are modified leaves, as their position on the shoot indicates and the tufts of leaves borne in their axils are in reality very short lateral branches, on which the flowers are borne.

Several species formerly included in the genus Berberis are now generally considered as a separate genus Mahonia and are characterised by their spineless branches and large compound leaves, which may carry as many as twenty leaflets. The best known of these is the common Mahonia, B. Aquifolium, a shrub much