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
'Blue Bell'
True blue dahlias remain a dream, but Dahlia 'Blue Bell' gets delightfully close. Its fully double, rounded flowers open in rich violet-purple, with deeper tones gathered towards the centre and paler lavender-blue shading developing as the petals mature. Look closely and you'll notice how the broad, overlapping petals give each bloom a beautifully full shape without looking overly formal. Measuring around 10–15cm across, the flowers sit above fresh green foliage on striking darker stems. At around 80–90cm tall, Dahlia 'Blue Bell' has just enough height to mingle with other summer favourites, and flowers generously from midsummer until the first frosts. That cool, unusual colouring brings a welcome contrast to the warmer shades of a late-season border.
Try Dahlia 'Blue Bell' with pale pink cosmos, creamy dahlias or silvery foliage, where its purple flowers take on an almost luminous quality. It's especially lovely in a cutting garden, producing long-stemmed blooms that work equally well in loose, country-style bunches and more considered arrangements. Give Dahlia 'Blue Bell' a sunny, sheltered spot in fertile, well-drained soil, and provide a little support as the stems fill with flowers. Water during dry spells and pick or deadhead regularly to keep new buds coming. Start the tubers under cover in spring, or plant outside once frost has passed, then lift and store them frost-free over winter in colder gardens. Dahlia 'Blue Bell' proves that a flower needn't be genuinely blue to look rather special.
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 'Blue Bell'
- Flower colour
- Blue, violet, purple
- 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
-30%
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