Dahlias are half hardy, so keep them protected from frost. Pot tubers individually between February and April and grow them on in a greenhouse or bright indoor position. Alternatively, start them outside in May, once the risk of frost has passed.
Out of season
New
Dahlia
'Sweet September'
In the softer light of late summer, Dahlia 'Sweet September' looks particularly at home. Its magnificent decorative blooms open in gentle powder pink, fading towards creamy white at their centre, with occasional hints of peach and lavender giving the petals added depth. Broad, neatly layered petals build into a generous, rounded flower, often reaching around 20 cm across. Rather than relying on dramatic contrast, the colouring has a lovely, almost porcelain quality, especially when caught by the afternoon sun. Dahlia 'Sweet September' is an inspired companion for white cosmos, pale pink salvias and airy ornamental grasses, bringing a sense of calm to plantings that are still very much in full flower.
The name may suggest the close of summer, but Dahlia 'Sweet September' begins its display much earlier, flowering from July and carrying on until the first frosts. Growing to around 100–110 cm, it produces leafy stems topped with substantial blooms that deserve a little room to shine. Plant Dahlia 'Sweet September' in a sunny, sheltered border with fertile, well-drained soil, and provide discreet support as the flower heads develop. Regular cutting and deadheading will help keep new buds coming throughout the season. For an especially elegant arrangement, combine a few stems with cream dahlias and soft green foliage. In a vase, Dahlia 'Sweet September' brings the same gentle beauty indoors, proving that late-season flowers can be wonderfully understated.
Quantity
Plant profile
Plant calendar
For planting out later, use a snug-fitting 15–20cm pot filled with peat-free multipurpose compost. For a patio display, plant directly into a container at least 30cm wide and keep it somewhere bright and frost free until it can move outdoors.
Position the old stem facing upwards, with the tubers covered and the stem stump level with the compost. Tubers naturally vary in size and shape and may arrive without visible buds. Bent necks are usually fine if they remain firmly attached, so do not remove them.
Water after planting, then allow the compost to become almost dry before watering again while the tuber remains dormant. Once shoots and leaves are growing strongly, water more regularly, always allowing excess water to drain away.
Plant out after the last frost, once the plant is around 20–30cm tall and its roots hold the compost together. Space dahlias approximately 30–50cm apart in borders, allowing less room for compact varieties. Water thoroughly after planting.
Water regularly during active growth and deadhead or cut flowers often. Dahlias usually bloom from July or August until the first frost, although later-planted tubers may start in late August or September. In autumn, lift, clean and dry the tubers, then store them somewhere cool, dry, airy and frost free.
- Botanical name
- Dahlia 'Sweet September'
- Flower colour
- Pink, cream
- Tuber size
- 1
- Established height
- 70cm-1m
- Established spread
- 30-50cm
- Growing skill
- Easy to grow
- Habit
- Upright
- Hardiness
- Half hardy
- Leaf colour
- Green
- Mouse resistant
- No
- Plant spacing
- 5 tubers per m2
- Pollinator friendly
- No
- Position
- Sheltered
- Rabbit resistant
- No
- Scented
- No
- Soil acidity
- Any
- Soil moisture
- Free draining
- Soil type
-
Loam
Sandy
Multipurpose compost
Loam-based compost - Suitable for
-
Large containers
Borders
Gravel gardens
Coastal gardens
Cottage gardens
Low maintenance gardens
Cut flower gardens - Sunlight
-
Full sun
Partial shade - Toxicity
- No report
- Years to establish
- 1st year
Good for cutting
Thrives in full sun
Perennial
Packed in paper
Low maintenance
Top-size tubers
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