«Work in the Garden»

Lake County Mail, Issue 31, 24 December 1947, Page 6

«Work in the Garden»

By J. W. Goodwin, N.D.H., N.Z., F.R.H.S., Massey Agricultural College

Planning for Autumn Colour There are a few trees and shrubs which flower in the autumn. The others are ripening their growth in preparation for next season’s display, whilst many deciduous members prepare to don the brilliance of their autumn foliage. floral colour in beds and borders is provided by annuals and perennials. Of the latter the most notable are the pink, blue and mauve of the Michaelmas daisy and the yellow and orange of perennial sunflowers. Their flowering, though free and coiourful, is not sustained over a long period, though an excellent succession may be planned. The enthusiast may ask: What may 1 plant to flower over a long period and broaden the autumn colour range? The answer is, The dahlia,” that queen of autumn flowers, first colour shows towards the end of January and extends until the growths are cut by frosts in April or May. There is probably no other genus which has made so much advancement as the dahlia during recent years, though the claims of gladiola and chrysanthemum are considerable. There has oeen all-round improvement in habit, form and colour range, the most notable being the way the flowers arc carried on good stems showing them to full advantage, and the production of types suited to all. For those who dislike the “ giants ” there are mediumflowered miniature and pom varities. For those with insufficient room or poor shelter there are the dwarf and bedding types. Keynotes to long and successful flowering are:—(l) Thorough preparation of the soil; (2) a wellbalanced supply of nutrients; (3) disbudding and removal of spent flowers. The dahlia takes its name from Dr Dahl, who first introduced to Europe the ancestors of our modern plants. There were several species, mainly scarlet and yellow in colour, and all except one semi-double type were singles. They belong to the great daisy family, the “ Compositae,” and are closely allied to cosmos and coreopsis. All were natives to Mexico, as was the dahlia juarezii the forerunner of the cactus dahlia. Lover of the Sun Dahlias will grow in a wide range of soils, the ideal being a well-acratcd soil which is retentive of moisture, lo be well aerated it should be reasonably well drained and thoroughly cultivated. To be retentive of moisture a soil requires a good humus content. The dahlia loves the sun and should not bo planted in shady places. The ground may bo double-dug, preferably two or three months before planting. This is not always possible and, if prepared just prior to planting, only wellrotted farm manure or like material should be incorporated in the lower “spit” of soil, when digging. The ground must be thoroughly firmed by tramping prior to planting. This is particularly important with dahlias if sturdy growth and a well-ballanced root root system are to be obtained. Similar treatment is necessary where smaller groups are to be planted in the mixed or herbaceous borders. Planting time varies with the district. Though greatly changed from the early Mexican types, they receive a severe setback if frosted. November is the usual month, and planting may continue until Christmas-time. In many districts they will survive quite successfully as perennials and will now be making new’ growth. It is usual, however, to lift the tubers, after growth has been frosted in the autumn, and store them in sandy soil on the sunny side of a fence or shrubbery. These stored plants will also be showing growth. Do not plant the full clump back again, as large numbers of shoots will be produced which will crowd one another. Divide the plants by pulling the old stalks apart and disentangling the tubers. Should this be difficult, cut down the centre of the stalks, and separate the tubers that way. Select those tubers with welldeveloped shoots or “ eyes ” and cut away surplus or damaged tubers. There arc usually a few rather long shoots. These may be shortened back to the lower pair of leaves. Off to a Good Start Tubers may be planted on their side with the young shoot in a vertical position. Depth should be three inches to the top of the tuber, or in light soils an inch or more deeper. Nurserymen seldom supply tubers. The usual means of supply is by rooted cuttings or “ green plants,” as they are generally known. Many growers prefer “ green plants ” for raising exhibition blooms, but equally good results may be obtained from tubers. Always set a small cane or stake to plant to. The young shoot may be tied to this, and a larger stake may later be inserted in the same position without damage to the tubers. Planting distances vary with the type —dwarf kinds 18 inches to 2 feet apart, medium growers 2 to

2% feet, and strong growers 2} to 3 feet. If plenty of organic material has been incorporated in the soil, it will be advantageous to give a light dressing of superphosphate when planting. Keep the soil well cultivated and allow the plants to branch naturally, except perhaps the large-flowered kinds, which may be grown on single stems and later allowed to develop three to four branches. Disbudding is essential for those varieties which develop flower buds only a few inches below the terminal bud. If all are allowed to develop, the steins remain short and are unsuitable for picking. Too many flowers will result in none of them being fully developed, and with short stems many are hidden from view T by foliage or other flowers. The two buds, developed in the axils of the first leaves below the terminal bud, should be removed when young, and sometimes the next two* lower down. More flowering growth will “ break ” from lower down, so nothing is lost and the plants are much more attractive. For show blooms disbudding is heavier, retaining only the crown bud on each shoot. Flowers are usually fully expanded in from four to five weeks of the bud showing first colour. Early Youthful Troubles Once they arc well-established and showing flower, surface hoeing should be stopped, as surface roots, sometimes termed flower roots, will be damaged. It is an excellent plan to mulch the plants with any well-rotted strawy manure or similar material. This will protect these surface roots and conserve moisture. Once the plants are flowering freely, it will be advantageous to water if the plants flag; although, if necessary, they will withstand fairly dry conditions. Liquid animal manure, the colour of weak tea, may be applied at this stage. Blood and bone may be used after rain or watering. Alternatively a complete chemical fertiliser consisting of 6 parts superphosphate, 3 parts of sulphate of potash, and 1 part of sulphate of ammonia may be made. Always apply in small quantities as over-manuring has a tendency to give course, malformed blooms and soft foliage subject to disease and wind damage. Bo guided by the vigour of your plants and always manure and water between the plants and not against the stem. Dahlias may be attacked by greenfly and thrips, particularly in the younger stages, and more noticeably with green plants. Control with “ Black Leaf 40.” In a moist, humid climate or prolonged dull weather a fungous may occur as a mealy blotch on the leaves. This may bo controlled by sprays of Bordeaux (summer strength) or Colloidal sulphur. Do not spray when the sun is very hot or the leaves are flagging. Virus diseases gave dahlias a very severe setback a few years ago. The only cure is “ fire.” Destroy any sickly plants with mottled and distorted leaves. Ahvays purchase new plants from a reliable source. Caterpillars occasionally make their appearance and may be killed when disbudding or, if necessary, spray with arsenate of lead. ©■rouping for Effect Most effective displays may be made by grouping the plants for mass effect according to their height. May I again recommend the pencil and notebook for jotting down names, heights and colours of those you fancy. Not all show-bench varieties are free-flowering subjects, so before purchasing check up with the grower. Space will not permit that I classify or recommend varieties —look them up in the nurseries at flowering time. Dahlias may be raised from seed sow r n under glass in August and planted out in November. Varieties will show considerable variation, but a good seed strain will produce showy effects and, perhaps (who knows?) something really outstanding. The “ Coltncss Gem ” typo, of which “ Unwin’s Hybrids ” are the best strain, may be raised annually from seed and used for bedding. They grow about 18 inches high and may be depended on to give a long and colourful display. May I add that the newer cannas, with their bold attractive foliage and brilliant flowers, require conditions

similar to the dahlia. Staking is not necessary and, of course, no disbudding is required. Best treatment is to plant in bold groups of three to five plants. Check on the height of the different varieties before planting. They may vary , from two to four feet in this respect.