Home Featured plant Dahlias: complete growing guide

Dahlias: complete growing guide

Admiring the dahlias at the 2016 Harrogate Autumn Show
Admiring the dahlias at the 2016 Harrogate Autumn Show

A touch of the tropics in my new border

I’m going all out for dahlias this year – not just the little single Bishop’s Children I’ve grown from seed in previous years.

Dahlias have undergone a complete transformation in status over the past few years – no longer confined to show experts grown solely for the early autumn traditional flower shows or in a cut flower bed.

This is what put me off for so many years – huge, fake-looking blooms standing alone in a vase in a marquee – how do you use such flowers in a natural setting?

The answer is in a tropical-style planting scheme – here, the flowers look right at home with big-leaved plants such as palms and cannas, which is how I’m going to use my new arrivals.

My three varieties were part of a Chocolate Orange selection from the RHS – who couldn’t love that – to tone in with the hot oranges, purples, and yellows the bed will contain. (More of this when the bed is finished – this spring’s big project.)

Here are the varieties – all like full sun, fertile, humus-rich soil and flower from July until the first frosts:

  • Jescot Julie: Each petal has a burnt orange upper surface and a rich plum base and looks sensational when mixed with deep, blood reds and dark golden tones. Growing up to 8cm across, the flowers appear in small clusters on the upright stems. Height 75cm.
  • Arabian Night: Fully double, dark wine-red flowers with slightly incurved petals. Under certain light, the petals appear almost black. Height 1.2m.
  • New Baby: A ball-type flower which opens tangerine, deepening to vermillion, contrasting well with rich plums and purples. The colour intensifies as they mature. Height 80cm.

Potted guide: growing dahlias from tubers

  • Dahlia tubers can be planted direct outside after frost or started off in pots under glass in late
    winter to early spring (my choice).
  • Plant them horizontally approximately 5″ deep, making sure the ‘eyes’ are uppermost.
  • Allow enough room between each tuber so the plants can grow and spread to their full size without being overcrowded (if planting direct).
  • While in growth, provide a high-nitrogen liquid feed each week in June, then a high-potash fertiliser each week from July to September.
  • Stake with canes or brushwood if you live in a windy spot or the flowers are heavy.
  • After the first frost has blackened the foliage, lift and clean the tubers and allow them to dry naturally indoors. Then place the dry tubers in a shallow tray, just covered with slightly moist potting compost, sand or vermiculite and store in a frost-free place until next spring.


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