How do I plant dahlia tubers?

How do I plant dahlia tubers?

'Splendour Noire'

Plant dahlias for autumn colour and cut flowers

Dahlias are easy to grow and are invaluable for late summer and autumn colour when most of the herbaceous plants have finished flowering. They are available in a huge range of sizes and colours, from the dainty single flowered varieties to the huge cactus headed show varieties. They can vary in height from 30 – 150cm (12” – 5’).  Some also come with attractive red/bronze foliage. The single varieties provide a late summer feast for bees and other insects. They are great for cut flowers and can be grown either in the ground or in pots; grown in pots they can be put into the herbaceous border where a shot of colour is needed.


They require rich, fertile, well-draining soil in full sun.

Planting in the ground

Plant them in the garden or in pots around mid-April. If they are planted in the ground the emerging shoots must be covered with horticultural fleece if there is a threat of late frosts. They are heavy feeders so incorporate plenty of well-rotted farm-yard manure into the bottom of the planting hole. Top dress with a handful of a general purpose fertiliser, such as blood, fish and bone. Plant the tubers 10 – 15cm (4 – 6”) deep and 75cm (30”) apart. Water after planting to settle the compost and fill any air pockets. Keep them just damp. When they start to shoot take off all but the strongest 4 – 5 as if you leave a lot of shoots to grow they tend to be quite weak.

Dahlia Bishop of Llandaff

'Bishop of Llandaff'

Planting in containers

Planted in pots, they can be placed in the greenhouse which will produce flowers several weeks earlier than if planted directly into the ground. Gradually harden them off before leaving them outside after all danger of frosts has past. You will need a fairly large pot, at least 30cm (12”) in diameter and depth with good drainage holes in the bottom. Use good quality multi-purpose compost with a forkful of well-rotted farm-yard manure in the bottom, and again sprinkle some blood, fish and bone over the surface after planting the tuber. Plant only one tuber per pot, 10 – 15cm (4 – 6”) deep. Water after planting and keep them just damp.

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Profile Image Angela Slater

Angela Slater

Daughter of a farmer and market gardener so have always had a connection with the outdoors, whether it was keeping animals or producing fruit, vegetables and cut flowers. Along with my work at Hayes Garden World I also have a smallholding, mainly breeding rare breed pigs. I gained an HND and BSc in Conservation and Environmental Land Management, as a result I am an ardent environmentalist and have a keen interest in environmentally friendly gardening. In my time at Hayes I worked for several years in the Outdoor Plant and Houseplant areas.