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Herbaceous Perennial

Dahlia coccinea

scarlet dahlia

A variable tuberous perennial, usually 1.2-1.5m high but can reach to 3m high, with branched, brown-purple stems, toothed leaves up to 40cm long, dark green above and paler below. Single flowerheads, 8-10cm across, have golden centres surround by ray florets which are usually bright orange-scarlet but may be yellow, orange, dark maroon or many-coloured, from summer to autumn

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Ultimate height

1–1.5 metres

Time to ultimate height

2–5 years

Ultimate spread

0.5–1 metres

Chalk

Loam

Sand

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

East–facing or South–facing or West–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Asteraceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Clump forming
Genus: Dahlia are tuberous rooted perennials with pinnately divided leaves and showy flowerheads, double in many cultivars, in summer and autumn
Name status: Correct
Plant range: Mexico to Guatemala

How to grow

Cultivation

Plant tubers 10-15cm deep in fertile, humus-rich, well-drained soil, in full sun; cut back to near ground level in mid-autumn, then in mild areas and on well-drained soils leave the tubers in the ground and protect with a deep organic mulch, while in colder areas or on heavy soils lift and store the tubers and replant in late spring after all danger of frost has passed; for more advice, see dahlia cultivation. This species is one of the parents of many garden cultivars

Propagation

Propagate by basal softwood cuttings taken in spring from shoots from stored tubers, or divide the tubers, ensuring that each division has a viable bud

Suggested planting locations and garden types

Patio and container plants
City and courtyard gardens
Cottage and informal garden
Wildlife gardens
Cut flowers
Flower borders and beds

Pruning

Deadhead to prolong flowering

Pests

May be susceptible to aphids, capsid bug, earwigs, caterpillars, slugs, glasshouse red spider mite, and onion thrips

Diseases

May be susceptible to powdery mildews, dahlia mosaic virus, cucumber mosaic virus, tomato spotted wilt virus, storage rots, leafy gall, crown gall, dahlia smut, grey moulds, fungal leaf spot, Phytophthora, Sclerotinia, Verticillium wilts, and virus diseases

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