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
Deluxe
Dahlia
'Columbus'
Just like Christopher Columbus we have searched far and wide on journey of daring, dahlia discovery and have struck gold (well, lilac) with the delightful Dahlia 'Columbus'. A pretty pompon dahlia that will stand its ground with almighty flower power in a spectacular summer border. It’s a ball of purple and lilac perfection, with each pristine petal suffused with white with darker, rich-lilac undersides. Not only is Dahlia 'Columbus' a long-flowering treasure to enjoy in the garden, even better news is that it grows more blooms to replace any you pick. So go ahead and feel free to cram your flower bounty into a vase and enjoy them in your home too.
The soft purple blooms of Dahlia 'Columbus' combine well with deep purple, white, pastel shades and the more brazen colours that dahlias can offer, such as magenta pink and coral orange. For a complete contrast in flower shape and tone, try pairing Dahlia 'Columbus' with 'Honka Black' for a two-tone display of light and dark. Pot up the tubers and grow them on for a few months before planting into borders for best results.
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 'Columbus'
- Flower colour
- Lilac, 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
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