Dahlias are brilliant for bringing late summer colour to your borders. Cool whites, hot pinks, burnt oranges, intense burgundies and every single shade in between – these tuberous perennials have bags of impact, versatility and character – you just can’t lose. Flower shapes and sizes vary enormously, too, so there’s bound to be one that suits your planting scheme. Waterlily, cactus, peony, pompon – the names of the different blooms are hugely evocative in themselves so take heed – looking through specialist catalogues can be highly addictive!
Dahlias perform particularly well when paired with other late-flowering perennials. Verbena bonariensis is a classic planting partner, and rudbeckias, echinaceas, nicotianas and salvias look equally effective. You can also bring a prairie look to your garden by dotting the tubers through foaming grasses such as stipas and calamagrostis.
When it comes to plant care, dahlias are easy to look after, provided a few simple guidelines are followed. Let’s take a quick masterclass in their care:
The tubers are tender, so give plants a head start by potting each one up into a container of multipurpose compost. Position the fat, finger-like tubers just below the surface and leave the old growing stalks just above. Water in well, label and place in a well lit, frost-free area.
The tubers will begin to grow new shoots within a few weeks. If you have multiple shoots, you can take cuttings to bulk up your stock. Slice off individual shoots at the base and insert into pots of open, gritty compost. They’ll root within a fortnight when placed in a heated propagator.
Once all risk of frost has passed, you can plant your tubers out into your flower borders. Check the final height of your particular variety – some dwarf types grow to only knee height, whereas other more lofty varieties can ultimately tower well over your head.
While dwarf dahlias don’t require staking, the taller types do. Insert stout bamboo canes or hazel poles next to each stem and gently secure together. Pinching out the growing points of each stem will result in side-branching and more, yet slightly smaller flowers. Exhibition growers wanting dinner plate-sized blooms will often allow just one bloom per stem.
Dahlias make excellent cut flowers. You can either leave your blooms on the plant to enjoy a display in the garden, removing the faded blooms as they develop, or cut them for the vase. Either way, continually removing the flowers from your plants will encourage a succession of new blooms.
Finally, in October when risk of frost is imminent, lift and store your tubers for winter. Gently tease them out of the soil, cut back all the stems, dust with sulphur and store in slatted trays in a frost-free spot. The tubers can then be potted up again in the spring. Those in very mild areas with free-draining soil can try leaving their tubers in your flower borders for winter.