Dahlia – Dahlia hybrids

CARING FOR DAHLIAS THROUGHOUT THE YEAR

JANUARY

Advice given for February also applies this month.

FEBRUARY

To propagate from cuttings, which produce the best plants, start the tubers into growth by re-boxing them in moist peat or compost. Do not simply moisten dry peat used for winter storage. A temperature of about 16 °C (60 °F) is needed. Remove the cuttings when the shoots are 5-8 cm (2-3 in) long.

MARCH

SOW seeds of bedding dahlias at a temperature of 18°C (64°F). Prick off the seedlings into boxes or into POTS.

Take cuttings from tubers started into growth last month. Once the cuttings have rooted, which takes about three weeks, pot them individually into 8-9 cm (3-3 1/2 in) pots.

APRIL

Continue taking cuttings from tubers and potting up the rooted cuttings individually as they become ready (after about 3 weeks).

Outdoors, prepare dahlia beds from about the middle of the month. After adding organic matter and fertilizer, and reducing the surface to a fine tilth, mark planting positions and insert supporting stakes.

Towards the end of the month plant last year’s dormant tubers outdoors if you are not taking cuttings from them.

Harden off bedding dahlias and rooted cuttings, ready for planting out once frost is not a risk.

IN the south, plant out from the last week of the month onwards, provided plants have been hardened off in a cold frame for at least a fortnight. In northern counties and Scotland delay planting for another week or two.

Watch for aphids on young shoots, spraying if necessary.

JUNE

Remove the growing points on plants to encourage side growths. Remove growths from the leaf axils of the top two pairs of leaves.

Tie plant stems to the supporting stakes.

Spread an organic mulch around growing plants.

JULY

Remove all dead flowers to ensure continued flowering.

Continue to tie growing plants to their supporting stakes.

Spray against aphids and other pests as necessary.

AUGUST

Continue July’s routine tasks.

A liquid fertilizer, applied as a foliar feed, will help to keep plants growing and flowering during the later months of summer.

SEPTEMBER

Dead-head, feed and spray against pests as necessary.

When frost has blackened the upper half of the foliage (which may not happen until November) cut the stems down to within 15-23 cm (6-9 in) of the ground. Lift and label the tubers, THEN place them upside down under cover to dry.

NOVEMBER

Lift and dry the tubers if this was not done during October. After a fortnight examine the tubers for signs of rotting. Remove damaged parts, dusting these and around the crowns with sulphur. Place the tubers in boxes of dry peat or sawdust, crowns exposed, and store in a cool but frost-free place for the winter.

DECEMBER

Advice given for November also applies this month.

Overwintering dahlias

As soon as autumn frosts blacken the foliage, cut down dahlia stems to about 23 cm (9 in). Lift the tubers, stand them upside down to drain before storing them in boxes of dry peat, in a frost-free place.

The first Dahlias arrived in Europe from Mexico in the late 1700s, and ever since then have been extremely popular with gardeners.

There are thousands of hybrids, all derived from three Mexican varieties. These plants have been divided into groups, based on the appearance of the flower. They include decorative, semi-cactus, large and medium pompons and ball Dahlias. However, they all have several features in common: they have long, slender tubers, hollow stems and shiny leaves with saw-toothed edges.

The tube-like centre of the bloom is surrounded by one or several rings of florets. The flowerhead can be single or double, depending on the number of florets.

The number of colours found in Dahlias is seemingly limitless. They range from snow white through yellow to a red so dark that it looks almost black.

Dahlias can be anywhere from 30cm-2.4m (1-8ft) in height. The lower-growing cultivars and hybrids are rather compact.Dahlia - Dahlia hybrids

Through The Year

May—August

Plant the tubers in a good soil-based compost and cover to a depth of 5-10cm (2— 4in). To grow just a few large flowers, remove all but one or two strong stems. Remove lower side shoots as the flowers develop.

September—February Dig up the tubers before the arrival of the first frosts. Leave on about 10cm (4in) of old flower stem, but cut out any soft or damaged parts of the tuber. Allow to dry in a warm room for several days before storing them. A temperature of 7°C (45°C) is ideal for storage.

March—April

March is the time to divide the tubers to increase your stock of plants. Take them out of storage and plant in equal parts peat and sand. Put in a frost-free place and keep the compost moist but do not water the tubers themselves. When the eyes on the tubers have swollen, divide the tubers, ensuring that each section has an eye. Plant in sandy compost and return to a frost-free spot.

Pests And Diseases

Holes in the leaves and flowers are most likely caused by earwigs. Treatment: Remove all old, hollow stems so that the earwigs have nowhere to hide.

D Leaf edges turn black due to black spot (a fungus carried in the compost). Treatment: Destroy the affected plants. Thoroughly clean out the container and add fresh compost before growing other plants in it.

Greyish deposits on the leaves and stems are grey mould.

Prevention: This disease needs damp conditions to develop. Water your Dahlias by soaking the ground and roots, not by overhead watering. Discard any mouldy plants.

A yellow mosaic pattern on the leaves is a sign of mosaic virus. Treatment: There is no cure; destroy your plant.

PLANT CARE

Dahlias are not difficult to care for. Remove withered flowers and stems. Stake taller plants, which may otherwise become top heavy.

 

 

Dahlia 

 

  • Potting: Dahlia tubers must be dug up in autumn or winter, stored and replanted in the spring. Use a good soil-based potting mixture.
  • Water generously and regularly in the summer, avoiding the leaves if possible. The tubers must be kept dry in the winter.
  • Feeding: Feed 2-3 times during the summer with a standard liquid fertilizer.

BEST GROWTH ENVIRONMENT

  • Light: Grow in an open position in full sun.
  • Temperature: They will thrive at normal spring and summer temperatures, but the tubers must be dug up before the first frosts of autumn. Store tubers at about 7°C (45°F), and make sure the temperature never drops below freezing.

Buying Tips

  • Dahlia tubers are available in spring for planting out when the danger of frost has passed. Garden centres and nurseries should have a good selection. If you have any difficulty, try a specialist supplier.
  • Choose plump, firm tubers. Avoid any that are dry or wrinkled, as they can be difficult to revive.
  • So long as they are stored correctly for the winter Dahlias will live for many years.

A late summer- and autumn-flowering perennial, the Dahlia is available in numerous varieties and hybrids, all of which are derived from plants originating in Mexico.

POPULAR CULTIVARS OF DAHLIAS TO GROW

Following are a few of the many good cultivars that seem to attract particular attention in most public gardens: ‘HAMARI GOLD’ Recent introduction to the Giant Decorative group, with large golden blooms. Giant Decoratives are more suitable for exhibition than for general garden decoration.

‘HOLLAND FESTIVAL’ Giant Decorative. Large apricot and white blooms, 23-25 cm (9-10 in) in diameter. Has been around for many years but is still very popular.

‘JOHN STREET’ Small Decorative. A single-flowered red, producing plenty of blooms right through the season.

‘NINA CHESTER’ Small Decorative. White tinged with lavender. Although this cultivar has been around for many years, it is still one of the best whites of this type.

‘PENSFORD MARION’ Yellow, flushed with orange.

Unidentified dahlias, Volunteer Park Dahlia Ga...
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‘Dons Diana’. Reddish-purple. Both these cultivars are Pompons, producing many flowers about 5 cm (2 in) in diameter. They are good for garden decoration and also make attractive indoor arrangements.

‘CHERIDA’ An excellent Miniature Ball type, peachy-orange in colour and forming a sturdy plant. The flowers are produced on stiff stems right through the season. A reliable performer.

‘HAMARI DELICE’ A fairly recent white-flowered introduction to the Miniature Ball type.

‘SALMON KEENE’ Large Semi-Cactus. Medium-sized blooms of blended orange and salmon.

‘Yellow Spikey’ Medium Semi-Cactus. Continuous supply of yellow, spikey blooms right through the season. Borne on stems well above the foliage.

‘YMA Sumac’ Medium Cactus. Has a compact habit, making staking easy. Flushes of yellow flowers.

‘Red MAJORETTE’ A recent introduction in the Small Semi-Cactus group. Flowers produced above the foliage on good stems. Ideal for cutting.

‘So DAINTY’ Small Semi-Cactus. Colour classed as tangerine, but could be called pale bronze.

 

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