DAHLIA

P. Dahlias are first-rate plants for amateurs as they can be grown well with comparatively little trouble and are largely free from pest and disease attacks. They flower from late July or early August until the October frosts and give excellent results in town gardens. Dahlias make excellent cut flower material.

Soil Preparation and Planting:

Dahlias take a great deal out of the ground, hence the need for careful soil preparation. A medium to heavy soil with sound drainage is probably the ideal, assuming it is reasonably fertile. The ground should be double dug and plenty of compost, hop manure and bonemeal incorporated in the top spit. Alternatively, a base fertilizer comprising two parts each of hoof and horn and superphosphate of lime and one part of sulphate of potash, may be used. (The hoof and horn releases nitrogen slowly over a long period.) Stakes are inserted before planting to avoid damaging the tubers. One strong stake will suffice for each plant, each shoot being tied separately. Dwarf bedding dahlias do not require staking but the intermediate and taller growers should be supported, especially in exposed positions. A sunny position is desirable. Dahlias tolerate slight shade but may grow too tall with excessive foliage and fewer blooms. If possible, choose a position sheltered from winds as the flowers can be bruised even when the plants are firmly staked. Planting distances should be 3—5 ft. for the tall-growing types such as the Large Decoratives, 2 ½ ft. for the intermediate varieties and 15—18 in. for dwarf bedding kinds. A saucer-like depression should be made around each plant to facilitate watering and feeding. Planting out is best deferred until early June when all risk of frost has gone. Tubers can be planted a week or two earlier, although if frost seems likely, the plants must be covered with flower pots, cloches or newspapers.

Cultivation. Frequency of watering depends on the season. Dahlias need copious supplies of moisture during the summer, otherwise they are very liable to wilt in hot weather. During prolonged drought it may be necessary to water twice a week. On light soils mulching with compost, hop manure or damp peat, will help to conserve moisture and reduce the amount of hoeing needed to keep down weeds. Faded blooms should be removed promptly as sodden, flabby flowers tend to stick to healthy foliage. Formation of seed pods also delays further cropping. A top-dressing of quick-acting fertilizer may be given in July and well watered in if the soil is at all dry.

Some disbudding and thinning of overcrowded shoots are desirable if first quality blooms are wanted.

Pests and Diseases. Earwigs are troublesome in some gardens. The old-fashioned method of filling inverted flower pots with a little straw and fixing to the tops of the stakes should not be despised. BHG or Pyrethrin sprays are also effective. Capsid bugs, aphids and caterpillars can be tackled by BHC or nicotine sprays. Dahlias are subject to several virus diseases, causing mottling and streaking of leaves and stems, and stunted growth. Infected plants should be burnt as there is no known cure.

Choice of Varieties:. Modern dahlias vary in height from 18 in. to 5 or 6 ft. comprising a wide range of colours and varying formation of blooms. The following extensive selection covers the main groups.

Decoratives. These varieties have fully double, more or less flat blooms ranging from 3 to 12 in. in diameter. The Giant Decoratives are over 10 in. in diameter, the Large Decoratives 8—10 in., the Medium Decoratives 6—8 in., the Small Decoratives 3—6 in., the Miniatures under 3 in. Amulree: S. D. Turkey-red. Very free-flowering. 31/2 ft.

Ballego’s Glory: M. D. Maroon and gold. Very free flowering with long, hard stems. An old variety which has not been superseded. 4 ft. Blue Lagoon: S. D. Pale mauve. Very free-flowering. 3 ½ ft.Brandaris: M. D. Orange-scarlet and yellow. 4 ft.

Chorus Girl: S. D. Lilac-pink flowers held well above the leaves, with tough petals. Very lasting and borne on long, firm stems. One of the earliest varieties to bloom. 3/2 ft.

Crimson Flag: S. D. Crimson-scarlet. Another old variety still worth a place. 3 ft.

Edinburgh: S. D. Rich burgundy and white. Globular blooms borne on very firm stems. 3 ½ ft.

Gertie Hoek: S. D. Warm shell-pink. Excellent for cutting. 3 ½ ft.Helly Bouderwijn: S. D. White with broad, flat petals suggesting a water-lily. Excellent for cutting. 4 ft.

Hockley Nymph: S. D. Creamy-yellow. Lasts up to 10 days when cut. 3 ft. House of Orange: M. D. Coppery-orange. 4 ft.

Jersey Beauty: M. D. Salmon and rose-pink. Still worth growing, especially for cutting. 5 ft.

Kendal Pride: S. D. Rose-pink with a lavender sheen. 3 ft. Keeps its colour in cold autumn weather.

Lavender Perfection: G. D. Lavender overlaid with pink. 4 ft. Mrs Hester Pape: G. D. Wine-red. 5 ft.

Newby: S. D. Peach and saffron, a delightful colour blend which does not bleach in very hot weather. The wax-like blooms are long-lasting when cut. 3 ft.

Regal Choice: M. D. Glowing purple. 3 ½ ft.

Shirley Westwell: S. D. Vivid scarlet flowers on wiry stems. Useful for cutting. 3 ft.

Sonnet: S. D. Dark mahogany. 3 ft. Spindrift: S. D. White. Very free-flowering. 3 ft.

Stuart Ogg: S. D. Pale yellow with white reverse. Very long-lasting. 3 ½ ft.Sydney Balcombe: G. D. Deep crimson. 4 ½ ft. Terpo: M. D. Blood-red. 6 ft.

Virgo: S. D. Another good white with ball-shaped flowers. Excellent for cutting. 3/2 ft.

Cactus. This group also has fully double blooms but the outer or ray florets are usually pointed, and either straight or incurving. Sizes as for Decoratives.

Andries Orange: S. C. Small bright orange flowers, very freely produced. 3 ft.

Ballet Girl: M. C. Salmon-pink with long shaggy petals. Stems very firm. 3 ½ ft.

Brother Justinus: M. C. Apricot and yellow. Long, firm stems. 4 ft.Cheerio: S. C. Crimson tipped white. Compact habit. 31/2 ft. Cremon: M. C. Lemon and cream with narrow, incurving petals. 3 ft. Deerplay: S. C. Golden yellow. 4 ft.

Dignity: S. C. Cerise-crimson on yellow base. 4 ft.

Golden Autumn: M. G. Golden-bronze. 4 ft.

Jean Baxter: L. C. Lavender-lilac. Blooms held well above the foliage. 3 ft.

Kathleen Rogers: S. C. Bright orange-scarlet. 3 ½ ft.

Mary Case: M. C. Bright scarlet with some cerise. 4 ft.

Nagels Bijou: S. C. Salmon and coral-pink. Very free-flowering and excellent for cutting, especially for table decoration. 4 ft.

Peaceful: S. G. Soft apricot-pink, somewhat like the old Baby Royal. 2 ½ ft.

Pioneer: S. G. Deep yellow. 4.½ ft.

Purity: S. C. White. Long stems. Excellent for cutting. 3 ft.

Risa Grivell: M. C. Cream and rosy-lake. Long stems. 4 ft.

Scarlet Leader: L. C. Pillar-box red. Blooms on long, firm stems, held well above the leaves. 4 ft.

Sunlight: S. C. Golden-yellow. 4 ft.

Torch: M. C. Yellow and carmine. 37.2 ft.

Tornado: L. C. Orange-red. Long, shaggy petals. Keeps well when cut. 3 ½ ft.

Towneley Sensation: M. C. Glowing orange. One of the first varieties to bloom and useful for cutting. 3Y2 ft.

Vic: M. C. Crimson-scarlet with gold base. 3 ½ ft.

Pompons:

This group bears blooms from 2 to 4 in. in diameter. The flower heads are compact, the individual florets short and tubular.

Buttermere: warm yellow. Long stems. Excellent for cutting. 3 ½ ft.

Dr John Grainger: amber and apricot. Extra firm stems. 3 ft.

Lipoma: rosy-lilac. Useful for cutting. 3 ft.

Pink Beauty: deep pink with rose markings. Excellent for cutting but prefers a dry soil and dislikes shade. 3 ft.

Pride of Berlin: pale lavender-pink. An old variety, distinct in colour which is still wortii growing. 3 ft.

Purple Gem: bright purple. 2 ft.

Tunis: vivid scarlet. 3 ft.

Tellow Gem or Yellow Wonder: deep yellow. Prefers a heavy soil 3 ½ ft.

Dwarf Bedding:

This group comprises varieties which do not usually exceed 2 ft. in height. The flowers may belong to the Decorative, Cactus or any other section.

Brentwood Bedder: crimson-scarlet.

Downham: clear yellow.

Jescot Apricot: apricot-orange.

Marjorie Ember son: salmon-pink. Grows to about 2 ½ ft.

Maureen Creighton: rich scarlet.

Melville Castle: a very fine yellow which comes into bloom in early July.

Pride of Edentown: another vivid scarlet.

Rothesay Castle: cream and rose.

Rothesay Tellow: another clear yellow. Very free-flowering.

Varieties in other groups include the old favourite Bishop of Handaff with crimson-scarlet paeony-shaped blooms and purplish foliage. It is still worth growing if virus-free stock can be obtained. Several other varieties with dark coloured foliage are now available including the orange-scarlet Intensive.

Lifting and storing. As soon as frost has blackened the tops in autumn, lift the tubers and cut away the top growth to about 9 in. from soil level. On light soils a fork is the best tool, on heavy land a spade is preferable. If the earth clings to the tubers, expose them to the air for a few hours and it will usually drop off.

The remaining soil can be removed later with a blunt label. Where a large number of tubers is to be lifted, the soil can be cleared by water from a hose-pipe. Tubers should be turned upside down on a bench when drying to prevent water collecting in the hollow stems. Store in a cool, frostproof shed with good air circulation and where the temperature is about 45 degrees F. Never store dahlias in a warm cupboard as this may cause the tubers to shrivel. Boxes of sand, peat, dry soil or weathered ashes are all suitable. The tubers of some varieties, especially certain reds, do not keep as well as others.

Propagation by Cuttings and Division of Tubers. The green plants available from nurserymen for planting out at the end of May or in early June are produced from cuttings taken in winter. Dahlia cuttings may be taken during the week of February. Propagation from cuttings rather than from tubers ensures sturdier plants of even size. Starting off the tubers too early means that the cuttings grow too quickly and are unduly tall by planting out time. A bottom heat of 70 degrees F. is desirable (another reason for avoiding early propagation as by the end of February the weather should be a little warmer). Tubers should be stood on a mixture of peat and sand (covering with leaves etc. may lead to ‘drawn’ cuttings). Up to 12 cuttings (each 3 in. long) can be taken from one tuber. About 4 are inserted in a 2 in. pot which is stood in a propagating case (a box 8—10 inches deep and covered with a pane of glass is equally satisfactory). Water the cuttings and aim at a temperature of 60—65 degrees F. to encourage humidity. They should root in 2—3 weeks and can then be transferred to the greenhouse staging for a few days. Next pot on singly into 4 in. pots and keep well watered. After about a fortnight the plants can be moved to a cold frame for hardening off. Division of tubers may be undertaken in late March or early April. Make a clean vertical cut through the stems, ensuring that one or more tubers are attached to each piece of stem with a bud or growing point. Half-a-dozen plants can often be obtained from an average ‘clump’ although some varieties produce fewer tubers than others.

The divided tubers can then be planted out in their flowering quarters, covering with cloches etc. if frost threatens.

Dahlias can be raised from seed and certain strains will flower in 3—31/2 months from the date of sowing, if given the ordinary half-hardy annual treatment as for asters, stocks etc. Named varieties do not come true from seed and some of the larger types such as the Giant Decoratives are shy seed producers.

Recommended strains are: Unwin’s Ideal Bedding with semi-double, quilled petals and a wide colour range, the height varying from 18—24 in.; Autumn Festival with double, or semi-double flowers, again in an extensive colour range and borne on long, stiff stems. This strain grows to 2 y2 ft. and the leaves are the colour of copper beech.

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