PLANTING TREES AND SHRUBS

New Zealand Journal of Agriculture, Volume 78, Issue 5, 16 May 1949, Page 513

PLANTING TREES AND SHRUBS

TAESPITE the onset of winter, in most districts the soil is comparatively warm and in a fit state for the planting of shrubs and trees. The selection of subjects, planting technique, and the propagation of shrubs and trees from seeds . and cuttings form the principal theme of these monthly notes for the flower gardener by M. J. Barnett, Director of Reserves to the Christchurch City Council. z .

'T’HE first objective in planting trees and shrubs is to ~~ select subjects suitable for the soil and situation where they are to be planted and which may be expected to thrive in the climate of the district. For instance, certain shrubs, such as the rhododendrons, the azaleas which are now classed as rhododendrons, and the heaths generally dislike lime and therefore should be planted in a limefree soil. Also, though they prefer a reasonably welldrained soil, they , will not tolerate hot or dry conditions and should be given positions which are cool and do not become parched during dry weather. On the other hand, many shrubs will succeed in almost any type of soil and are excellent for dry positions and light soils. Foremost among these are all the species and varieties of Cistus, the rosemary, the lavender, all the hybrid brooms (.Cytisus) , the Spanish broom (Spartium junceum), the genistas, Caryopteris mastacanthus, the rock roses or helianthemums, the yuccas, and many New Zealand shrubs, such as Senecio compacta and Notospartium carmichaeliae. All of these are good flowering plants, and in poor soils and dry conditions it is much better to rely on them than to attempt the cultivation of more exacting subjects, which unless given special attention will only exist, whereas the others will thrive. However, such a wealth of material is available that no difficulty will be found in selecting trees and shrubs specially adapted for any soil and situation in the Dominion. A study of nurserymen’s catalogues and of gardening publications specially devoted to the cultivation of trees and shrubs will supply much of the information required. Not only must the subject chosen be one that will thrive under the conditions in which it is planted, but it must remain in keeping with the general surroundings. In its infancy or adolescence, so to speak, a shrub or tree may be all that is desired, but when it reaches maturity it may be much too large for its position or out of proportion with the rest of the garden. a Briefly, the following should be the determining factors when making a choice: The plants should be sufficiently hardy to succeed in the normal climate of the district. They should be of such a type that they will thrive in the soil and situation given them. They should be of such a character that they form part of the general garden composition. ' When they have attained adult form they should not be . too large or out of keeping with their environment., Preparation of the Soil With a selection made, and the supply of the required numbers and kinds arranged, the next step is to prepare the soil in readiness for planting. Trees and shrubs are the permanent features of the garden, and too much care cannot be lavished on the preparation of the soil in which the plants are to have their being for years to come.

Where possible the ground should be trenched or cultivated to a depth of at least 2ft. If it is not of sufficient fertility, liberal quantities of organic manure should be worked into the soil, but at a sufficient depth to ensure that when trees or shrubs are planted the roots do not come into direct contact with the manure. Poor,

sandy, or light soils may be enriched by incorporating with them liberal dressings of leaf mould or decayed compost. These materials are better applied after the initial trenching has been completed, when they may be spread over the surface, dug in, and worked evenly into the soil with a strong garden fork. This operation' also serves to break up lumps and reduce the soil to an even texture. The eradication from the soil of all persistent weeds such as convolvulus, sorrel, twitch and couch grass, and Canadian thistle is imperative before any planting is done. Once such weeds become established among shrubs their eradication is most difficult and in some cases almost impossible. The setting out of plants immediately after the ground has been trenched is not advisable. It-is better to allow the soil to settle to an even consistency, which may take several weeks, after which it should be turned over with a fork as described and reduced to a uniform grade or level in readiness for planting.

Planting Precautions

When the package of plants arrives from the nurseryman it should be opened immediately and the plants carefully removed and separated. If the roots have become dry in transit, they should be steeped in a bucket of water until they are thoroughly moistened and have had time to absorb some moisture; the stems and foliage should be sprayed. If immediate planting is inconvenient, the plants should be heeled in in a sheltered part of the garden. Heeling in consists of opening a trench to a sufficient depth to accommodate the roots comfortably, placing the soil immediately at the back of the trench, laying the plants with their roots in the trench and the stems at an angle of about 45 degrees, and covering the roots with soil, which is formed by pressing it down with the heel of the foot. ' ' ....... ...

The holes or pits to receive the roots should have been prepared in advance. In the case of a border of shrubs the exact spot that each specimen will occupy should have been marked with a peg, consideration being given to the growth dimensions of each and their relative positions as individual specimens and as units in the general composition and effect aimed at. Each hole should be sufficiently deep and wide to take the' whole of the root system without having to force the roots into it. It should be Ift. greater in diameter than the width of the roots when spread out to their fullest extent, allowing a space of 6in. , all round between the outer tips of the roots and the sides of the hole. The planting of trees and shrubs even a few feet high is a 2-man job. One holds the specimen upright and in the correct position in the hole, while the other, after having spread out the roots in all directions, carefully fills in the soil, which should not be dry and lumpy nor yet wet and sticky.

A too-common practice when planting is to fill in all the soil in one operation after the roots have been placed in position. Though sufficient for compact, fibrous-rooting subjects like rhododendrons, that method will not suffice for other plants, particularly many of the trees, on which the lateral or secondary roots radiate at varying heights from the central axis or main taproot. Therefore, to en-

sure successful planting the method is first to cover the lower layer of roots, firm the soil, then spread out the roots immediately above, cover these, and so on until all the roots have been adequately covered with soil. The soil must be worked evenly among the roots throughout; the per-

son holding the specimen can assist with this work. Should the soil be on the dry side at the time of planting, each plant should be given a good watering. If there is any fear that wind will loosen upright plants, each one should be supported with a stake fastened securely to the main stem but in such a manner as not to injure it.

Points ;to ■ observe when planting trees and shrubs are: v Remove with a . sharp knife all broken and badly-damaged branches and roots, but retain as much of the rooting system as possible, and especially all fibrous roots. Never allow the roots to become dry; those on plants that are not to be set out immediately should be kept covered with moist soil or a wet sack. Plants to be taken from pots should have the crocks removed, the topsoil carefully scraped away, and the outer roots freed from the ball of earth. . When heeling in or planting be careful that the boot does not’ scrape or otherwise injure the bark of the stem or roots. Do not plant too shallowly, so that when the soil settles the surface roots are exposed, or too deeply; usually a soil mark on the stem shows the depth at which it was planted in the nursery, and 1 or 2in. below this is sufficient.

Above all, treat each plant as a vital, living organism and not as a mere inanimate object. Propagation from Seed Seeds of such trees as the oaks, the . beech, the pink and white horse chestnuts, and the sweet chestnut may be : sown now. These seeds, though comparatively large, do not hold their power of germination for long and should be sown shortly after they have fallen from the trees. They may be sown directly into prepared seed-beds in- a sheltered part of the garden or, if that is inconvenient at the time, they should be stored in damp sand or leaf mould until late winter or early spring, when they will just be starting to show signs of germinating. The seeds must not be stored dry as is the practice with most kinds. If only a few plants are required, a limited number of seeds may be sown in pots ■or in seed trays and allowed to grow there until they are sufficiently large to be transplanted to the open ground.

\ Seed of most berried plants, such as the holly, the hawthorn and other species of thorn (.Crataegus), and the cotoneasters may also be sown. In such cases the seeds are stratified—that is, they are placed in layers in a container of damp sand, kept in a cool

place for at least 4 months, and then sown, sand and seeds, in drills in a prepared seed-bed. Some, such as the holly, may be left in the stratified state for 12 months. , Hard-coated seeds of such plants as kowhai and wattle germinate more readily if the horny outer seed coat is softened. Boiling water poured over them has proved effective in hastening germination. Seeds of roses, rose species, and the Pyrus or crab apples germinate more readily if they are submitted to a few degrees of frost. The usual method adopted is to sow them in pots after the seeds have been cleaned by rubbing them through' sharp sand and then plunge the pots in sawdust, or coke breeze outside where they will be exposed to the winter weather. Propagation from Cuttings Many shrubs and some trees may now be propagated successfully from hard-wood cuttings. The following list gives some indication of the plants that can be raised in this manner: Privet, flowering currant, forsythia, philadelphus, spiraeas, senecios, olearias, broad-leaved laurel, Prunus pissardi and its varieties, Prunus pollard!, Platanus orientals, tamarisk, veronicas, poplars, and willows. For the cuttings, firm, well-ripened growths of the previous season should be selected; weak, spindly, and soft unripened wood should not be used. The cuttings are cut into lengths of about 12in. and are made by cutting the base square across the stem with a sharp knife about jin. below a joint or node and removing the top or unwanted portion immediately above a

joint. Some cuttings take root better with a heel to them; a heel is a small portion or slice of the old wood attached to the base of the younger wood. / When the cuttings have been prepared they should be inserted in neatly-prepared trenches in the open ground, preferably in a well-sheltered position where the soil is always moderately moist. The cuttings should be buried to half or two-thirds of their length, and to provide a more suitable rooting medium a layer of sand should be placed at the bottom of the trench. The soil should be well heeled or made firm so that the cuttings do not become loosened by wind or frost. Once planted, the cuttings should not be disturbed for 12 months, by which time they will have rooted and z be ready for transplanting. Plants to be Pruned The pruning of rambler roses, as advised last month, may be continued. Such shrubs as the golden-leaved elderberry, the tamarisks, and Buddleia variabilis and its variety He de France may be pruned now. As all of these are robust growers and produce both better foliage and better flower heads from the young growths that will develop later, they should be pruned hard back to within a few inches of the old wood. Spring-flowering and early sum-mer-flowering shrubs, such as the forsythia and the flowering currant, should not be pruned until after flowering.

Plants Recommended by the District Council of the Royal New Zealand Institute of Horticulture for Planting in the Waikato

Native Trees Deciduous Exotic Trees Houhere (Hoheria populnea) Beech (Fagus sylvatica, ordinary Kawaka (Libocedrus plumosa) and purple-leaved forms) Kowhai (Sophora (Edwardsia) Birch (Betula papyrifera and B. tetraptera) alba) Puiple ake-ake (Dodonaea Horse chestnut (Aesculus carnea, viscosa purpurea) the red horse chestnut) Red beech (Nothofagus fusca) desia polycarpa (preferably Tanekaha (Phyllocladus both sexes) trichonianoides) Japanese cherry (Primus - serrulata, var. J. 11. Veitch ch...ho Laburnum vulgar e txonc tsnruus Liquidambar styraciflua 'Andromeda (Pieris) japonic a Maidenhair tree (Ginkgo biloba) Azalea indicum Splendens ln oak <&™rcus palustns) Camellia sasanqua . . . . Primus mume and P. cerasifera Chimonanthus fragraws (allspice) • 1, rnosert fl. pl. . ■ Daphne odora Tulip tree (Liriodendron . J Erica melanthera tulipifera) Feijoa sellowiana (bears edible : fruit) - , Kalmia latifolia Native Shrubs Kolkwitzia amabilis , ,r, • Leucospermum reflexum Kumar ano u (Pomaderns Lilac (Syringa vulgaris and vars. elliptic a) buffoon, Marechai Lannes, and Mairehau (Phlebalium nudum) ■ x Souvenir de Louis Spath) Pink manuka' (Leptospermum Magnolia soulangeana scoparium var. martini and Rhododendron, various var. keatleyi) Rose species (Rosa moyesii, R. Pomifera, and R. rugosa) _' ' ■ _ ' ' Smoke bush (Rhus cotina atro- Evergreen Exotic Trees purpurea) ■ , L Viburnum, opulus and V. earlesii Acacia bailey ana and A. leprosa Waratah (Telopea specio sissima) Magnolia gtandiflora

Climbers Bulbs and Bulbous Plants Abutilon megapotamicum (syn. Anemone, various /I. Freesia (hybrids and F. Akebta quinata i; - burtonii) ■ Celastrus scandens (both sexes , . needed) • Gladiolus, various Jasminum primulinum Iris (Spanish, English, Dutch, Kennedya comptoniana and I. reticulata) Lathyrus tomentosus (Argentine Lilium auratum, L. croceum, L. , , P ea . • ’ , henryi, L. longiflorum, L. Mandewtlla suaveolens marhan, L. form'o sum,' L. Oxypetalum caeruleum regale, L. testaceum, and L. Rose, various . . ■ tigrinum. Fit is mconstans lowi XT . - , •,, XT o i -i Wistaria, various Narcissus (especially N. Soled dor) Herbaceous Plants - Nerine (N. bowdenii, N. fotherAster (Michaelmas daisy, , gillii major, and N. especially A. frikarti) sarmensis) Astilbe (Spiraea), . various Delphinium,*°various Plants for lhe Rock Garden Gerbera jamesoni (needs drain- ..... age and a sunny aspect) Aubrietia, various Gypsophila paniculata (Bristol Freesia, various Fairy) Helianthemum (rock rose), Hehanthus quertifohus (Autumn various Ir£ 10 bearded Primula (Wanda and P. Lupins, various malacoides) Pentstemon, various New Zealand, rock lily Phlox, various (Arthropodium cirrhatum) Polyanthus, various > Lit hasp mum prostratum Kniphofia, various . , . ... - . . , Rudheckia, especially var. Herb- Irls > various dwarf species stone Veronica, various

In districts where severe frosts are experienced the pruning of evergreen shrubs should be delayed until later.' Now is a good time to attend to the pruning ana removal of unwanted branches of all 'deciduous-trees.

Overhaul of Rock Garden

. . A general overhaul of the rock gar-. den, if it has not been attended to already, should be proceeded with at once. All strong and rampant-growing subjects which tend to grow beyond their allotted space and to crowd out smaller but more treasured plants should be restricted to their proper confines. Replanting may require attention, and, if required, the pockets and interstices should be topdressed with a good compost of friable loam, leaf mould, and sharp sand. Closegrowing alpines that tend to suffer from rot because of their foliage com-

ing into close contact with the cold, moist soil should be protected by a thin layer of coarse sand or |in. quarry grit nlaced between the basal leaves and the soil. A sharp look-out should be kent for slugs, which find the rock garden a safe and convenient harbourage for the winter months. Care of Plants under Glass Schizanthus which has been growing under glass for early flowering will require potting on and staking. To induce a bushy habit the tips of the leading shoots should be pinched out. If they are forward enough, calceolarias should be potted on into 6in. pots, in which they will flower later. Pots or bowls of hyacinths, tulips, narcissi, lachenalias, and freesias should be placed under glass for forcing into early bloom as required. Winter-flowering Plants Two good, perfectly-hardy, winterflowering herbaceous perennials are Helleborus niger (the winter rose) and Iris stylosa. Both are of such easy culture that too frequently little attention is given to them.

Though it will succeed in a variety of situations, the hellebore gives of its best when planted in a soil that is rich in organic matter and cool and moist 'at all seasons. Dryness at the root it does not like, especially during its growing season, which begins immediately after the flowering period and continues until early autumn. Open but sheltered spaces between bushes of rhododendrons or underneath the protecting canopy of foliage of such shrubs as the Japanese maples suits them admirably. A light mulching of fallen leaves in ' autumn not only protects the flowers from mud stains splashed up by raindrops . but also causes an elongation of the flower stem, a valuable asset when cut flowers are required. The fresh young foliage develops with the advent of spring, and from then onward the plants should not be neglected. Copious waterings should be given during periods of dry weather, and as an aid to conserving moisture in the soil as well as to supply material for surface feeding a good mulching with compost or half-decayed farmyard manure should be spread among, the plants during November. Unlike the hellebore, Iris stylosa prefers a warm situation and a welldrained soil. Some gardeners believe that it will succeed in the poorest of

soils and for this reason it is too frequently given but casual attention. Though it would exist where many another plant would fail, it will respond to good treatment. When the plants are starved the flowers are fewer, . of shorter stalks, of paler colour, and lacking in substance. It is an evergreen, producing fresh foliage each season, but the old foliage will persist for years, gradually dying and remaining mixed through the greener leaves, giving the plant an untidy and bedraggled appearance. To prevent such a state the old foliage may be cut over entirely a few inches above ground in spring as soon as the flowers are over. -• The young growth will follow immediately and remain fresh and green until the. following year, when the' process may be repeated. Experience over many years’ has proved that this practice injures neither the vigour of the plant nor its propensity for flowering. - The delicately-textured flowers are so easily bruised and injured that when they are required for cut blooms they should be cut just before the petals unfold, and - placed .in water; within a few hours they will open out to their full beauty. Autumn-flowering Plants /-• Escallonia montevidensis is a lateflowering evergreen shrub or small tree which is perfectly hardy and will succeed even in relatively-poor soils. The specimen illustrated at the head of this article is growing in a poor, sandy soil. ' ' , ■, Amaryllis belladonna (the belladonna lily) is one of the most popular of autumn-flowering bulbous plants. It thrives best in a position fully exposed to the sun . and in a soil that is perfectly drained and contains a considerable amount of gritty substance, such as rock fragments or coarse sharp sand. The bulbs should .be planted just below the surface of , the soil. Once established, they should remain undisturbed for years.

Plants Recommended by the District Council of the Royal New Zealand Institute of Horticulture for Planting in South Canterbury /

Native Trees Native Shrubs Herbaceous Plants . Annuals or Biennials Pittosporum eugenioides r ' , , . A . -p-. ... Sophora tetraptera Leptospermum scopanum Aster King George Lavatera Loveliness Dodonaea viscosa atropurpurea keatleyi tsngeron Elsie xr; r <> Hoheria lyallii Clianthus pwniceus Lychnis vise ana fl. pl. Stock Beauty of Nice Metrosideros lucida . Notospartium carmichaeliae pink Nemesia strumosa Suttoni ' ■' Evergreen Bx.«. Trees t re,. “hgi Beauty Marigold Harmony Magnolia grandiflora Gypsophila Bristol Fairy Phlox drummondi. Cedrus deodara . ' Exotic Shrubs Scabiosa caucasica Blue Cryptomeria japonic a ana C. . . . Mountain ' elegans Pieris japonic Helenium Moorhein Beauty ■■ ' Plants for the Rock Garden Arbutus unedo Camellia sasanqua Hiryu rianis iui me nuvn. uaiuc.. Acacia baileyana ‘ Chimonanthus fragrans ■ ■ Hydrangea Heinrich Seidal Bulbous Plants Lithospermum Grace Ward Deciduous Exotic Trees Rhododendron fragrantissimum Cyclamen neapolitanum Quercus palustris Azalea mollis Koster s Brilliant T.iltum regale t . . Prunus pissardi nigra Cotoneaster Conspicua Narcissus Soleil d’or Gentiana sino-ornata Pyms (Malus) atropurpurea Erica \melanthera Gladiolus Picardy Pulmonaria angustifolia Prunus serrulata J. H. Veitch Magnolia st ell at a Nenne bowdeni '7 Betula papyrifera -:'A . • Spartium junceum Iris Wedgwood Erica carnea Praecox Rubra

HEELING IN PLANTS

THE RIGHT AND WRONG METHODS OF PLANTING

WORK IN THE FLOWER GARDEN