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
Dahlia
'Mystery Day'
The classic Dahlia 'Mystery Day' has all the hallmarks of a good vintage, and has been bringing character, class and a touch of glamour to gardens for more than 30 years. In common with other decorative dahlias, Dahlia 'Mystery Day' has huge double, dinner-plate blooms up to 20cm across. But it stands out above the rest with its deep wine-red to purple petals, as rich and velvety as claret, each one tipped crisply in white. Backlit by the rays of summer sun, this creates a scintillating effect, adding more depth to those rich burgundy tones. A favourite in classic country gardens and stately homes, Dahlia 'Mystery Day' is a flower to treasure as one of the greats of the summer border.
Growing to just over a metre tall, Dahlia 'Mystery Day' holds its bold blooms up proudly, and has a longstanding reputation for keeping them upright. They jostle attractively with other plants and colours in the garden, working especially well with those rich autumnal shades as summer progresses and the light softens. Keeping on top of the deadheading means that you’ll be able to enjoy these beauties for a long season, from summer up to the first frosts. A standout plant for a big container, Dahlia 'Mystery Day' will thrive with a rich growing medium and regular moisture. You can also bring the drama of this dahlia into the home as a cut flower thanks to its excellent vase life.
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 'Mystery Day'
- Flower colour
- Wine red, purple, white
- 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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