Continuous Colour in the Mixed Flower

New Zealand Journal of Agriculture, Volume 82, Issue 6, 15 June 1951, Page 533

Continuous Colour in the Mixed Flower

Border ERBACEOUS borders are a great “ ■ asset in the flower garden. They require only a reasonable amount of time for their maintenance and, if the initial planting has been careful, can provide a continuous display of colour for the greater part of the year. However, a Common fault of herbaceous borders in New Zealand is that they have considerable non-flowering periods because the initial planning has been done not to provide continuity of flowering, but rather to provide a home in the border for every plant which appeals to the gardener. In this month's article for the flower gardener C. K. Ellis, Horticulturist, Department of Agriculture, Dunedin, lists species suitable for the mixed border according to the times of year during which they bloom rather than according to colour combinations.

A COMMON belief is that in the colder parts of the country no species suitable for the mixed border can be grown to provide colour during the coldest period of the year. In regions such as Central Otago that is largely true, but in most other parts of the country at least a few species will provide winter blooms. In autumn and spring, of course, many more species flower prolificacy, but the great majority of worthwhile herbaceous plants are summer - flowering species. The numbers of blooms in spring can be increased without great difficulty by planting breaks of spring-flowering bulbs, such as narcissus, earlyflowering tulips, and a host of other early-

flowering bulbs. Autumn flowering likewise can be supplemented by the planting of bulbs which produce flowers during that period. Therefore the only period during which there is a real scarcity 'of flowers is mid-winterfrom June to August. The species listed above are arranged according to their flowering times for the benefit of gardeners who propose setting a section of their garden aside as a herbaceous or mixed border. . The suitability of species for the soil in which they are to be grown also often raises problems. As with all other types of gardening, species to be grown in the mixed border should be selected for their suitability to the

soil type with which the gardener has to contend. The lists above enumerate plants which will thrive under normal conditions with a reasonably friable soil, neither very acid nor very alkaline, and of average fertility. Other soil types occurring in New Zealand gardens are the chalks, peaty or acid soils, exceptionally heavy soils, and exceptionally poor or infertile soils. The lists on the left are a guide to the types of plants suitable for such conditions, and because of the natural paucity of herbaceous species a few small types of shrubs and some bulbs are included to make the gardener’s task a little easier.

Photograph by Sparrow Industrial Pictures Ltd.

Bulbs grown in pots or pans for decoration in the house should be watered sparingly until the flower buds appear to ensure that the leaves will not be longer than the flower stalk at the time of blooming. After the bud has appeared above the soil water may be applied more liberally, but the soil must not be allowed to become waterlogged.

Drainage of the soil is a factor well worth consideration at this time of year. Especially in a new garden, a good plan is to dig a few holes here and there and leave them open during the wettest season of the year. If any waterlogging occurs below ground level, it can then be seen and remedial steps planned. Very few, plants can tolerate waterlogged soil, even for a short period.

Frosts and thaws are advantageous on heavy clay soils because they break a cloddy condition down-to one of fine tilth. Therefore such soils are improved by being left dug in late autumn or winter without further cultivation until the ground : is required in spring. However, such a breaking-up effect is a disadvantage to newly planted shrubs, for it tends to loosen the soil about the roots. In such circumstances the soil should be trodden down after each series of frosts.

Gladioli may be planted in July in milder northern districts. It is still too early to. plant flowering-sized corms in most other parts of the Dominion, but cormlets may be planted so that they will have the

longest possible growing season. They should be sown 1 to 2in. apart and about l s m. deep. - Greenhouse plants such as gloxinias, streptocarpus, cyclamen, and tuberous begonias can be propagated from seed sown in July. Boxes or trays are filled to within an inch of the top with a finely sieved compost and thoroughly

wa tered through a fine rose. The seed j s sown thinly over the surface and, if it s covered with soil at all, a very light and finely sieved layer is sufficient. A sheet of glass should be placed over each box and the whole covered with brown paper to conserve moisture and exclude bright light. The boxes should be inspected frequently,

and as soon as the seedlings have appeared the glass and paper must be removed, or the small plants will become “drawn”. Iceland poppies should be inspected regularly from now on for symptoms of the virus disease known as spotted wilt. Infected plants never recover and are best removed from the soil with a trowel and burnt. To reduce the spread of the disease to a minimum the gardener should wash his hands thoroughly after tending infected plants and before handling healthy ones. Because of the importance of this disease the following description of the symptoms is quoted in full from “Textbook of Plant Virus Diseases”, by K. Smith:

The first symptom is a clearing of the veins of the youngest leaves. These leaves become somewhat twisted, cease growth with the appearance of symptoms, and gradually turn yellow. The whole centre of the plant acquires a pallid, stunted appearance.. In affected field plants, where the rosette of leaves is usually more vigorously developed than in pot plants, a bunched habit is acquired because of the stunting and yellowing of many central leaves. Frequently purplish blotches appear on some of the yellowed leaves or on their midribs or petioles, and a necrosis (dying of the tissue) may set in and destroy the petiole while leaving the leaf blade unaffected. Although diseased plants usually remain alive for weeks in a stunted condition, a rapid extension of the necrosis seen on the petioles sometimes causes the sudden death of the plant. The flowering stems of affected poppies are frequently much twisted and bent over; when they do grow erect they are shorter than normal, more sappy, and brittle, and the buds frequently open badly. The opening of the buds may be delayed until after erection from the recurved position, so that the tip of the bud points vertically upwards, a condition not seen in healthy poppies. The sepals, instead of lifting normally from the receptacle, often confine the petals so long that they burst out laterally. On the flowering stems

of many affected plants water-soaked areas may appear from which a drop of milky-white latex ■exudes. This soon becomes brown on contact with the air and dries to a small hard pellet. The exuding of a brownish drop of liquid from necrotic patches on the leaf petioles or midribs in their early stages also occurs at times.

Japanese irises (.Iris laevigata) are fibrous rooted and may be divided and replanted during July. They need a .soil which is moist all year round, but not necessarily waterlogged or boggy, and rich in organic matter.

Lawn aeration is important not -only because it improves the physical -condition of the soil, but also because it promotes root growth and thus encourages vigour in the turf. Aeration can be obtained by pushing a garden fork in every few inches as far as it will go and drawing it straight out again without any levering.

Roses should be pruned now in all but the coldest districts, where frosts may kill any induced new growth or the ends of pruned branches, thus ruining the shapes of the bushes. For ordinary garden display all young .shoots should be cut back to within 9 to 12in. of their bases, and side .shoots and all old, dead, or weak shoots should be removed. Where exhibition blooms are required much harder pruning is needed, but this results in fewer blooms and a less shapely bush and cannot be recommended to the home gardener.

Seed of quite a number of plants suitable for bedding displays should be sown this month under glass. Among such plants are antirrhinums, Verbena venosa, calendulas, lobelias, East Lothian stock, nemesia, Torenia Joumeri, and Phlox drummondi. The method of sowing is the same as that described for greenhouse plants except that the compost need not be so fine and the seed should be covered more heavily after being sown.

Shrubs which flower on the current season’s wood can be pruned in July by cutting back to within a few inches ■of the older stems all the shoots which .grew and flowered during the previous season. Carrying out this treatment annually ensures a constant supply of new flowering shoots and prevents the shrubs from tending to become straggly. A few of the shrubs which

should be pruned thus are Ceanothus Gloire de Versailles, Spiraea japonica var. Anthony Waterer, Clematis jackmani, and Buddleia variabilis. Sweet pea seedlings raised from seed sown last month or earlier, and germinated in a frame or greenhouse, should now be gradually hardened off by being given more air and less protection. They may be planted out in the milder districtslsin. apart if exhibition blooms are wanted and 4 to 6in. apart for mass display. Other Work for the Month Thin to 8 to 9in. apart annuals sown in the borders in autumn. Continue planting out bedding plants in the milder districts.

Take cuttings of perpetual flowering carnations under glass. Remove dead fronds from ferns and spread a layer of compost over the roots. Plant hardy herbaceous perennials such as helemum, rudbeckia, kniphofia (red-hot poker), and gaillardia. Be careful not to overwater pot plants at this time of year. They do not take up much water during winter and readily become waterlogged. lf the soil is wet and cold when trees and shrubs arrive from the nurseryman, they should be heeled in until conditions for planting are better.

Plants for Chalk or Shrubs for Acid Soils Perennials for Heavy Soils Limy Soils Arctostaphylos Aster Achillea Bocconia Dianthus ' Helianthenum Delphinium Gornus Erica Gaultheria Azalea Rhododendron Chrysanthemum Goreopsis Selenium ■ Kniphofia Lupinus Rudbeclcia Geranium Perennials and Bulbs for Solidago Saxifraga Acid Soils Monarda Papaver orientale Pae onia Pyrethrum Lilium eandidum, , L. chalcedonicum, _ L. testaceum, L. tigrinum, and L. umbellatum Lilium canadense, L. giganteum, and L. pardalinum ■ Primula beesiana, P. bulleyana, P. coclcburniana, P. japonica, and P. pulverulenta Perennials for Infertile Soils Achillea Althaea rosea (hollyhock) Alyssum saxatile Digitalis Gaillardia Geum Lupinus Papaver orientale Dianthus Statice latifolia

Soil Preferences of Herbaceous or Mixed Border Plants

August to October Delphinium Helenium Alyssum saxatile Dianthus (pinks) Kniphofia A Dictamnus caucasicus Dianthus (pinks) Dictamnus caucasicus Montbretia Kniphofla Slontbretia Aubrietia Echinops vitro Rudbeckia Doronicum Erigeron speciosus Solidago Iberis Funkia sieboldi April to June Polyanthus Gaillardia grandiflora Aster cordifolius Saxifraga cor difolia Geranium ibericum Gypsophila paniculata Aster ericoides Aster novae-angliae October to December Hemerocallis awantiaca Aster novi-belgi Aquilegia hybrids Dielytra Geum .. Iris germanica (bearded iris) .. L unaria Papaver orientals Inula glandulosa Linum perenne Lupinus polyphyllus Lythrum salicaria Monarda didyma Oenothera glauca Paeonia Pentstemon barbatus Chrysanthemum Ilelianthus Iris foetidissima Kniphofia Nepeta mussini Rudbeckia Schizostylis ' December to February Phlox decussata June to August Potentilla Eranthis hyemalis Achillea millefolium rubrum Pyrethrum Helleborus niger Achillea ptarmica Scabiosa caucasica Helleborus orientalis, ; Aconitum ■ Statice latifolia ‘ H. viridis, H. lividus, and Anchusa italica Thalictrum II. corsicus Anemone japonica February to April Iris alata, I. bakeriana, Bocconia cor data Achillea I. reticulata, and Campanula latifolia . Aconitum ftscheri I. unguicularis Centaur ea montana Aster amellus Petasites fragrans Centranthus albus Chrysanthemum Schizostylis coccinea Chrysanthemum maximum Chrysanthemum uliginosum Sternbergia lutea Coreopsis grandiflora Echinacea purpurea Tritoma

Flowering Periods of Herbaceous or Mixed Border Plants