Thanks to varieties ranging from giant dinner-plate dahlias to compact gallery dahlias just 30-35cm tall, your garden can be a colour extravaganza during summer – whether you have extensive borders or pots to fill. They’re wonderfully low maintenance for the amount they give back – aside from the possible need to stake them if they have very large flowers, they’ll provide you with continuous blooms during summer and autumn with very little of fuss. And when you succumb to temptation and pick a few for the vase, the plants will eagerly replace the cut stems with new flowering shoots.

Dahlia planting basics

Dahlias love rich, well-drained soil in full sun. They’ll still give you lovely blooms without a lot of soil preparation, but enriching the soil by digging in a mulch when planting will give you even better results. Like most bulbs and tubers, they don’t like poorly drained soil, so dig in plenty of compost or topsoil to raise the level of your garden beds slightly if you have heavy soil.

How to plant Dahlia tubers

— Dahlias are half hardy, which means they should be kept frost free over winter and during spring.

— Dahlias should be potted up into individual pots and grown on until they are around 30cm tall before planting into borders. Pots should be snug-fitting for the tubers, around 15-20cm diameter pots are usually ideal. We recommend using multipurpose compost.

— If growing dahlias in patio containers, you can plant the tuber directly into a patio container which is at least 30cm diameter using multipurpose compost and position the container in a bright, frost free place until risk of frost has passed, then move it outside.

— To give you dahlias a head start, pot them up and grow them on in a greenhouse or a bright position indoors between February and April. Alternatively, you can plant the tubers into pots and grow them on outside in May or when risk of frost has passed.

— Dahlia tubers are naturally different shapes and sizes and they may not have visible buds when supplied in February or March. Some tubers may be bent at the neck, which is the narrow part where the tuber joins the crown. Some of the outer skin may come away around bent necks, but providing the tubers are firmly connected by inner fibres this should not cause a problem, these tubers should not be removed.

— Plant with the stump of last year’s stem facing upwards. The tubers should be fully submerged but with the stump just level with the soil surface.

— Water in after planting and and position the pots in a bright, frost-free place. While the tubers are dormant, you should allow the soil to almost dry out before watering again. Once in growth, you can water regularly.

— Dahlias should be transplanted when they easily come out of the pot with the soil held together by the dahlia's roots, typically when the plant reaches 20-30cm tall.

— When planting into borders, space the dahlias around 30-50cm apart from each other. Compact varieties don’t need so much space.

— Water-in thoroughly after planting and continue to water regularly once in full growth, but only when the soil appears to be nearly dry.

— Dahlias usually start to bloom in July or August, depending on the weather and then they were planted. It is common for dahlias started in late spring to take until late August or September to begin flowering.

— Deadhead regularly throughout the growing season to encourage more flowers. Dahlias will continue to flower until the first frosts in autumn if regularly cut or deadheaded.

— Around the time of the first frost in autumn, or by late October, carefully lift the tubers out of the border using a spade. Cut off the stem around 3cm above the tubers, wash soil from the tubers and leave them in a frost-free, airy place to dry out for a few days. Once the tubers are fully dry, they can be stored in crates or open shallow boxes in a cool, dry and frost-free place for winter.