Dahlia Growing Guide

Published on 25 March 2025

A vibrant way to bring life to your garden!

The highlight of the summer and autumn garden. Flowering for months, they mix well when planted amongst your perennials and annuals providing you with an abundance of flowers bringing something glamorous, stylish and distinct. Single-petaled or open-flowered dahlias are a great way to encourage bees and other wildlife into your garden to enjoy the nectar-rich centres!

Do they like sun or shade?

Dahlias need full sun and if possible, a slightly sheltered position away from strong winds.

When should you plant dahlia tubers?

In April, to get your dahlias going, plant the tubers in simple plastic pots and keep the tubers slightly moist, undercover in a light, frost-free place. When there are three pairs of leaves growing from the main shoot, carefully cut or pinch out the tips, this creates a bushier plant with more flowers.

Plant them out when the dangers of frosts have passed, usually in May or June. If the foliage appears before the frosts are over use either a cloche or horticultural fleece to keep the temperature a few degrees higher.

What soil do they like?

Dahlias thrive in rich, well-drained soil. When starting tubers off, half fill a 3-litre pot with peat-free compost, place the tuber in the centre of the pot ensuring the stem is facing upwards and cover with more compost. Later on when you are ready to plant them out, incorporate plenty of good quality compost into the soil or containers.

Can I grow dahlias in a container?

Dahlias can be grown in both the ground and in containers

Cut flowers

The best time to cut them is in the cool of the morning, choose flowers that are open as the buds will not open once they're cut!

Dahlia Pests

Dahlias attract many beneficial insects, but they are also attractive to some which you don't want like their nemesis, slugs! Soon you will be able to see shoots growing and it is very important to keep on top of the slug control.

Natural wool pellets

Derived from British wool these pellets work best in pots by forming a matting over the top of the soil which the slugs don't like to cross as it is an irritant and absorbs moisture from the underside of the pest.

Strulch

Cover the surface of the soil with a generous layer as this helps protect against any late frosts, as well as reducing slug damage throughout the growing season. It also reduces weed growth whilst retaining moisture in the soil, perfect for organic gardening as it enriches the soil structure over time as it decomposes.

Slug Pellets

Natural, organic and safe to use unless you're a slug or a snail! Sprinkle pellets evenly and thinly over the soil around your plants. They contain ferric phosphate which occurs naturally in the soil and acts as a bait and the pellets are metaldehyde-free!

Support

We recommend planning ahead by using plant supports early as it is much easier to grow through them rather than to thread the stems through later in the season. Staking dahlia plants is crucial in achieving perfect blooms by helping the leafy stems rise to the sun and prevent wind damage, tie the dahlias in every couple of weeks.

Our rust effect, single stakes with a circular divided ring on top is an excellent support for dahlias.

Feeding and Watering

Water your dahlias frequently, especially if they are in pots and even more so during hot weather as they prefer moist soil.

Dahlias grow very quickly once they get going and it is a good idea to feed throughout the summer at weekly intervals with plant food such as liquid seaweed to keep your hungry and thirsty dahlias happy.