Annual Plants for the Flower Garden

New Zealand Journal of Agriculture, Volume 79, Issue 2, 15 August 1949, Page 177

Annual Plants for the Flower Garden

VvTTTH the advent of Septemher in New Zealand definite signs of spring appear everywhere, the weather becomes warmer, and on every hand is evidence of plant life awakening from its winter sleep into vigorous growth. With these portents every gardener becomes imbued with the urge to be up and doing, to sow seeds and to raise plants for the approaching flowering season. The treatment of annual flowering plants is the main theme of this month’s article for the flower gardener by M. J. Barnett, Director of Reserves to the Christchurch City Council.

"COR creating colourful displays in “ the flower garden plants generally described as “annuals” are among the best. Literally, annuals are those plants which grow from seed, flower, and produce seed within 12 months and die after the seed has ripened. However, some few annuals may be induced to flower in the second season if all the seed heads are removed immediately the flowers have passed their full beauty, and many perennial plants, such as the antirrhinum, flower the first year from seed and are more often than not treated as annuals. There are also some plants, such as the lobelia, which are killed outright by frost and therefore are raised annually from seed, though it is possible to perpetuate them by cuttings from . year to year. For the purpose of this article all plants that can be and are flowered from seed within 12 months will be treated as annuals. Three Classes of Annuals

Annuals may be divided into three classes: First, the hardy annuals such as sweet peas, cornflower, and godetias which can be sown in the open ground and which will bloom within the same season; second, the halfhardy annuals such as French and African marigolds that generally require to be raised in heat under glass in the initial stages of their growth and then transplanted to the open Sound after frosts are over and when e temperatures of the air and soil are. higher and more conducive to their requirements; and, third, the tender annuals such as celosias which are usually grown from seed to flowering in a greenhouse, but which may be transplanted to open ground and flowered with success in districts where cool temperatures are not experienced during summer. Annuals may be used for many purposes in the flower garden. Such plants as petunias, salvias, verbenas, and Phlox drummondi are excellent for bedding purposes, either by themselves or in conjunction with other subjects; for instance, Phlox drummondi makes a colourful display in a bed by itself or it may be used with good effect as a

groundwork in a bed of mixed dahlias. The display in the perennial or mixed flower border can be enhanced by planting or sowing annuals between and among the groups of perennial plants. As examples, a group of African marigold planted through or around a clump of oriental poppy will provide a continuity of bloom after the poppies have passed out of flower and developed that untidy appearance which they present during mid-summer and autumn; salmon-pink clarkia sown among a group of the’ tall, feathery Thalictrum dipterocarpum provides a pleasing contrast with the purple-mauve coloured flowers of the Thalictrum, which are carried well above the pink flowers of the clarkias. A border devoted entirely to annuals can be made one of the dominant features of the flower garden during summer. Many of the less exacting kinds, such as nasturtiums, petunias, and linarias, are excellent for covering up bare spaces that occur in front of a shrubbery. A number of annuals, such as sweet peas, the canary creeper (Tropaeolum peregrinum), nasturtiums (Tropaeolum majus and T. minus), and the several varieties of convolvulus and ipomeas, are also admirably adapted as climbers for covering trellis work or paling fences. The convolvulus and ipomeas, which have brilliant blue and pink flowers and succeed in a warm, sunny, sheltered position, must not be confused with that awful curse the white perennial “convolvulus,” which is not a true convolvulus but Calystegia sepium.

Sowing Methods Most of the hardy annuals may be sown in open ground during September. Some of them will succeed in relatively-poor soils, but the majority prefer a well-cultivated soil rich in organic matter. Practically all of them dislike being transplanted and grow much better when sown in the positions where they are to have their being and produce their flowers. Before they are sown the soil should be thoroughly moist— sodden, wet, or sticky, but in that friable state where it can be broken up readily and reduced to a fine tilth with a garden fork and rake. However, the soil should not be reduced to a dust-fine state which is likely to cohere into a hard crust after the first good rain or to entice sparrows to make a dust bath in it. With the soil prepared, the seed can be sown either in shallow drills or broadcast. If the seed is broadcast, the surface requires to be lightly but efficiently raked over to ensure that it is buried. If the soil is inclined to be loose, it should be firmed with the back of a rake or spade. Provided the soil retains its moisture and the weather is not dry, the seed should germinate within 10 days or a fortnight. To prevent rapid evaporation of moisture from the surface in dry, sunny weather, light branches of birch, manuka, or similar material may be laid over the areas sown down, but these branches should be removed as soon as the seedling plants appear above ground. Shallow drills made with a sharpened stick or the tip of a trowel provide a surer

method of sowing, as every seed sown can be adequately covered with soil. Whichever method is adopted, .the seed should be sown thinly. Most of the hardy annuals require from 4 to 6in. in which to develop, and if the seed is sown too thickly, the plants must be thinned heavily and repeatedly to prevent overcrowding. All of the hardy annuals mentioned in the recommendations which follow may be sown .to advantage in open ground. Characteristics of Annuals Acroclinium roseum has rose and white daisy-like flowers which are excellent for drying for winter use.

Flowers required for such a purpose keep their colour better if picked in the fully-developed bud stage or just when the flowers are fully expanded. This precaution also applies to the other “everlastings” such as helichrysums, rhodanthes, and xeranthemum. The last-named has deep purple and rosy violet flowers. Sweet alyssum forms, neat little bushes not more than a few inches high and literally covered with white flowers. It remains more compact and much more charming in appearance when sown in a comparatively-poor and hard soil exposed to . full light than it does when . given a good soil and a semi-shaded position, where

it grows more loosely and loses its true miniature character. Because of its neat, compact habit it makes an excellent edging plant for beds or borders. The variety Lilac Queen has become very popular for such a purpose of recent years.

Clarkias and larkspurs thrive, best when sown in good soil and when well grown provide cut flowers admirably suited for vases and bowls. Godetias are also first favourites; there are two types, the tall-growing varieties with flowers produced in long, loose sprays very suitable for cut flowers, . and the dwarf er varieties such as Sybil Sherwood which produce the flowers in clusters. .

. Other hardy annuals used extensively for cut flowers are nigella (love-in-a-mist), cornflower, sweet sultan, candytufts, and eschsch’oltzias, more familiarly known as jacky-go-to-beds or Californian poppies. In some localities the wild type of Californian poppy has become a pest on dry riverbeds and railway embankments, but several improved varieties with red, rich pink and rose-coloured semidouble flowers are well worth a place in the garden.

Mignonette will always be welcome in any garden for its sweet fragrance. It prefers a soil that is on the firm side and contains lime. One successful grower advocates giving the soil a dressing of lime before sowing the seed. The night-scented stock (Mathiola bicornis) is another of the best scented flowers. During the day it has little to commend it —in fact, it looks verv drab and inconspicuous—but on a calm evening it fills the air with its fragrance. A few patches of it scattered through the more outstanding subjects in the flower border repay anyone who enjoys a stroll through the garden when the heat of the day is over. The Virginian stock, though only a miniature plant, is more colourful and will grow in almost any soil and situation.

Gardeners who favour blue flowers cannot do better than sow Phacelia campanularia, the flowers of which are large and of a deep gentian blue. It grows freely in any good garden soil and is a most attractive plant when in full bloom; to use a hackneyed phrase, “No garden should be without it.”

Wherever there are gardens there will be nasturtiums. The dwarf types, of which there are many varieties and which do not spread excessively should be . grown more extensively than they are. On poor soils they remain more compact and flower more freely than when planted in good, fertile soils.

A number of other hardy annuals, such as the nemophila, Shirley poppies, viscarias, annual lupins, sunflowers, and the red linum {Linum rub ens), are all worth cultivating, but two more deserve special mention: Limnanthes douglassi, a dwarf plant with fern-like foliage and large butter-cup-like flowers which is very susceptible to dry conditions and should be given a cool, moist situation; and Platystemon californica, which has creamy, almost citron-coloured flowers. Both are miniatures admirably suitable for the front of the border.

In addition to the truly hardy annuals, several of the so-called halfhardy kinds may be grown successfully when sown in open ground in the warmer localities. Among these are nemesias, 10-week stocks, asters, love-lies-bleeding, jacobeas, and dimorphothecas. Many annuals have comparativelyshort flowering periods of only 4 to 6 weeks and therefore cannot be relied on to provide a continuous bedding display throughout the summer, as is expected of dahlias, geraniums, antirrhinums, and petunias. Nevertheless, they have their uses even in bedding displays. For instance, nemesias planted alternately with antirrhinums in a bed, being quicker to produce their flowers, will provide

a wealth of colour before the antirrhinums come into bloom. After the nemesias have passed over and have been removed, the antirrhinums will carry on the display. Experiment with Asters At one time the annual asters were among the most popular of flowers, but of recent years it has not been possible to rely on them as in the past because of the prevalence of disease among them. Experience has proved that asters will thrive on new soil that has not been under cultivation previously; second, that they are more subject to disease when transplanted; and, third, that the disease may be combated if the young plants

are watered at frequent intervals with a weak solution of permanganate of potash (condy’s crystals). The solution should be of a light rose-pink colour. In one establishment in Christchurch the following trials were made with asters on a comparativelylarge scale: An acre or more of ground which had been under cultivation for several years was prepared in readiness for planting. One half of the area was manured with stable manure and compost and the other fertilised with superphosphate. Some of the asters were sown under glass and pricked off into seed-trays in the usual way. Another batch was sown very thinly in seed-trays and allowed to

grow undisturbed until transplanted to the open ground. The third batch was sown in drills in the open ground and, apart from the necessary thinning, weeding, hoeing, and watering, was left undisturbed. Those raised under glass and pricked off into trays made more rapid growth, . but after being planted out had a higher percentage of mortality up to and during the flowering period. Those transplanted to the open directly from the seed-boxes had a smaller percentage of mortality. Those sown in the open ground and not transplanted, though a fortnight later in flowering, showed little evidence of disease and the number of deaths was very low. The photograph on the preceding page was taken when these plants were in full bloom in March of last year. The asters grown in the area manured with compost had a higher percentage of deaths than did those grown in the area fertilised with superphosphate. The soil originally consisted of a poor clay loam not more ' than 6in. deep overlying a clay pan with sand below. It is by no means a first-class garden soil. This experiment has been carried out for 2 years with practically the same result on each occasion. The asters were not grown on the same area each year. Propagation by Layering Many shrubs which are difficult to propagate from cuttings can be raised from layers successfully at this season. The method is as follows: — The spent surface soil around and beneath the bushes to be layered is removed and . replaced with a fine compost composed of a good loamy soil passed through a Jin.-mesh sieve, leaf mould, and plenty of sharp sand. The compost, which should be reasonably moist but not wet, should be made firm and even. A convenient healthy branch is then bent down carefully until it comes into contact with the compost. After it has been ascertained where the branch will meet the soil toward the tip, a wound is made with a sharp knife midway along the part of the stem which will be buried in the soil. The layer is then embedded in the soil and held firmly in position with one or more pegs made from 8-gauge wire. The pegged-down portion is covered with another few inches of compost, which should be given a thorough watering to settle and consolidate it. Apart from weeding and an occasional watering in dry weather, the layers should be left undisturbed for 12 months; indeed some, such as rhododendrons and magnolias, require fully 2 years to develop a sufficiently-good rooting system to warrant the layers being severed from the parent plants.

There are various methods of making the layer. Some plants will root if the portion to be layered is bent down and covered with soil. In most cases, however, a wound such as a tongue or notch is made to arrest the sap flow, thus causing a callus to form and inducing roots to develop at the injured point. To make a tongue the knife is inserted below a joint and the cut made upward toward it. For the notch method a notch is cut out

of the stem on the underside at the point where it is pegged down. . For some subjects with pliable stems the wound is made by giving the stem a twist which is sufficient to rupture the vessels and cells, thus causing rooting to take place at the affected point. Lime trees are frequently propagated in this manner. A tree that has been cut over will send up numerous, suckers around the stump. These suckers, if treated as explained, will root within 12 . months, when they can be cut away from the parent stump and grown on until they are ready for planting out as specimen trees. Sometimes, because of the habit and character of the bushes, bending the lower branches down to ground level for layering is difficult. In such

cases the compost is built up to a convenient height by means of turves as retaining walls so that the branches may be layered into it. In other cases the specimen to be layered is keeled over on to its side. This is effected by digging a trench round the bush and excavating the soil until it is possible to force the subject over carefully until some of the branches come into contact with the soil’s surface. Shrubs which may be readily propagated by layering include rhododendrons, azaleas, magnolias, cydonias (japonicas), Osmanthus delavayi, Rhus cotinus, camellias, corylopsis, enkianthus, viburnums, hamamelis, and garrya. Other Work for the Month Complete the pruning of roses as soon as possible and recondition the beds in which they are planted as described in last month’s “Journal.” Evergreen shrubs such as escallonias, buddleias, euonymus, Garrya eliptica,

and many New Zealand natives should now be pruned where it is necessary to improve their shapeliness. Evergreen climbers such as honeysuckle and ivy should be trimmed back now. Ivy is an excellent subject for covering walls and fences, but if left unchecked, it will become top heavy. To prevent that it should be cut back to the main stems each spring. Fresh foliage will quickly develop, and in a week or two the plant will again be completely covered with glossy green leaves. If necessary, herbaceous perennials such as michaelmas daisies, phloxes, Scabiosa caucasica, and pyrethrums may still be divided and replanted. However, this work must be treated as urgent so that the young growths that are developing rapidly will not receive a check severe enough to impair them for the rest of the season. To provide early supplies of flowers the first of . the gladiolus corms should be planted out into soil that has been well prepared in advance. If not already attended to, the corms required for later planting should be cleaned, placed in trays, and kept in a cool place to prevent their starting into growth too soon. Plant out violas, pansies, and in favourable localities, antirrhinums, and 10-week stocks that are sufficiently hardy after having been grown on under glass during the winter. Plants under Glass All pot plants under glass should • be overhauled and all those re- . quiring repotting should be attended to at once. This applies in particular to what may. be termed the permanent subjects such as palms, ferns, and aspidistras. Fuchsias that have been rested during the winter , will require immediate attention. Prune them where necessary, rub off all superfluous bark (which provides an ideal hiding place for mealy bug), remove the plants from their pots, carefully shake out the old soil, and repot them. To induce the production of fresh growths the plants should be syringed frequently with tepid water. Where plants are being hardened off in frames the lights should be removed on all favourable occasions. Sow seeds of gloxinias, streptocarpus, celosias, and tuberous-rooted begonias. Tubers of gloxinias and begonias that have been rested during the winter may now be started by placing them in trays of light, sandy compost. Do not water them too much at this stage; many of the tubers are saucer shaped, and if moisture collects and remains in the centres of them, decay will set in. Keep the compost moderately moist by light syringings. Cyclamen will now be at the peak of their flowering and, unless required for seed, all blooms should be removed as soon as they are over. As soon as the chrysanthemum cuttings have rooted they should be potted up into 3in. pots. Those established in pots should be placed in a cold frame and given plenty of air and light to prevent their becoming weak and spindly.

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

Evergreen Native Trees Kowhai (Sophora tetraptera) Pohutukawa (Metrosideros tomentosa), coastal Ngaio (Myoporumlaetum), coastal Totara [Podocarpus totara)Rata (Metrosideros robusta) Rewarewa (Knightia excelsa) Rimu (Dacrydium cupressinum) Native Shrubs Kaka beak (Clianthus puniceus) Senecio greyi ■ . Hebe speciosa Kumarahou (Pomaderris el lip tic a) Manuka (Leptospermum scoparium var. martini and ■ . keatleyi) Ake ake . (Dodonaea viscosa) Ramarama (Myrtus bullata)

Evergreen Exotic Trees Eucalyptus ficifolia, coastal Eucalyptus leucoxylon rosea Banksia serrata r . :■ Banksia ericifolia ’ She oak (Casuarina cunninghamiana) Dryandra floribunda . Deciduous Exotic Trees Liquidambar styraciflua Prunus blirieana Malus floribunda Quercus palustris Magnolia kobus var. borealis Betula pendula (syn. B. verrucosa') Ginkgo biloba Annuals Antirrhinums. Iceland poppies Nemesia Marigolds, French Stocks, 10-week

- Exotic Flowering Shrubs Camellia Duchess of York and .. Mathotiana . -■ " Rhododendron ponticum : ~ Forsythia ' intermedia spectabilis Podalyria calyptrata, coastal Protea. neriifolia "■ Prostanthera rotundifolid Ceandthus impressus ■ • Leucospermum reflexum, dry , position Cydonia japonic a Viburnum burkwoodi Herbaceous Plants Iris, bearded Kniphofia hybrids Dahlia Chrysanthemum, decorative . Carnation Phoebe ■ Scabiosa caucasica f Erigeron Elsie Pentstemon hybrids - • ■ Helenium, dwarf section. ',..5.

Bulbous Plants Agapanthus africanus (syn. A, umbellatus) Narcissus Soleil d'Or Freesia burtdni Lilium tigrihum ■ Lilium regale '".".'l.' ' Lachenalia aurea • ■ Gladiolus Picardy Iris xiphium var. Wedgwood and Yellow Queen Rock Plants Aubrietia hybrids Litho s per mum prostratum (L. diffusum) Phlox subulata Alyssum saxatile Erica darleyensis \ Daphne crieorum Nepeta mussini Campanula muralis (C. '■ portenschlagiana) ■ Dianthus. species .

[Reprinted from the "New Zealand Gardener,’- -

official organ of the Royal New Zealand Institute of Horticulture.

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

Evergreen Native Trees North Island kowhai (Sophora tetraptera) Lacebark (Hoheria populnea) Red beech (Nothofagus fusca) Southern rata (Metrosideros lucida) Dodonaea viscosa - atropurpurea Evergreen Exotic Trees Azara microphylla Cootamundra wattle (Acacia baileyana) Japanese cedar (cryptomeria japonic a elegans) Cedrus altantica glauca Cupressus lawsoniana lutea Winter-flowering Shrubs Chinese witch-hazel (Hamamelis mollis) Viburnum burkwoodi Erica darleyensis Daphne mezureum Wintersweet (Chimonanthus fragrant) Grevillea alpina dallachiana Garrya elliptica

Exotic Flowering Shrubs Forsythia intermedia spectabilis Magnolia st ell at a Telopea oreades Embothrium lanceolatum Callistemon citrinus Splendens Olearia gunniana Lavender Queen ' Azalea mollis (varieties) Rhododendron fragrantissimum Grevillea dimorpha Cytisus scoparius Crimson King Ceanothus edwardsi Cistus purpurea Brilliancy Deciduous Exotic Trees Prunus serrulata J. H. Veitch Pyrus malus eleyi Magnolia soulangeana Prunus blireiana Laburnum adami Native Shrubs Veronica andersoni variegata Veronica specie sa Clianthus puniceus rosea Leptospermum scoparium martini Senecio greyi

Berried Shrubs Cotoneaster serotina Stransvaesia davidiana Euonymus Handley’s Variety Eugenia ugni (Cranberry) Arbutus unedo Berberis noils on a e Flowering Bulbous Plants Anemone (varieties and species) Iris (Spanish, Dutch, English, I. reticulata, I. paviona) Gladiolus (varieties) Tulips (species and varieties) Daffodils (species and varieties) Hyacinths (varieties) Lilium (including L. regale, L. testaceum, L. henryi, L. tigrinum, L. auratum, and L. longifiorum) Rockery Plants Lithospermum prostratum Iris reticulata Cyclamen neapolitanum Gentiana acaulis Helianthemum vulgare (varieties) Tulipa kauffmanniana

Annuals Antirrhinum (Tom Thumb and intermediate varieties) Stock (10-week and Beauty) Phlox drummondi Nemesia (varieties) Marigolds (French and African) Petunias (dwarf bedding varieties) Lobelia Cambridge Blue Asters (varieties) M esembryanthemum criniflorum (Livingstone daisy) Herbaceous Plants Gypsophila paniculata Bristol Fairy Delphiniums (varieties) Polyanthus (varieties) Scabiosa caucatica (varieties) Pyrethrum (varieties) Gaillardia (varieties) Kniphofia (varieties) Myosotidium nobile (Chatham Island forget-me-not) Phlox decussata