If you’ve overwintered your dahlias, May is the time to plant them out in the garden.
While you can plant dahlia tubers directly into the soil, it’s good to give them a head start under glass, before hardening off and planting out in late May – learn how to pot up dahlia tubers in spring.
More on growing dahlias:
When you get to planting your dahlias in the ground, leave 15cm to 45cm between plants, depending on the ultimate size of your variety. Avoid planting dahlias in wet or shady sites, and dig the area over deeply before planting, incorporating lots of compost, to keep these hungry plants in top condition.
As for dahlia care, check out these expert tips on caring for dahlias.
Discover how to plant out dahlias, in this step-by-step guide.
You Will Need
- Sturdy wooden stakes
- Well-rotted manure
- Garden twine
Before planting out your dahlias, hammer several 1.2m stakes into the soil. Make sure they are firmly placed and unlikely to wobble, as these will provide support for your dahlias.
Dig a hole at the base of each stake, about twice as wide as the dahlia rootball.
Add a deep layer of well-rotted manure, home-made compost or or peat-free multi-purpose compost to the bottom of the hole, to increase nutrients and aid moisture retention.
Water each plant thoroughly before gently removing it from its pot. Tease out the roots, then settle the rootball into the hole.
Plant each rootball deeply, so the top is 5-8cm below the soil surface. This will help to support the brittle stems.
Using your heel, firm the soil around the plant, then water well so it settles the soil and soaks down to the roots.
Spread a 5-7cm-deep layer of mulch over the soil around the plant. This should stop it drying out in summer.
Weave garden twine back and forth between the stakes, running it at different heights to hold the stems.
Once the plants are 30-50cm tall, cut out the tips of the main stems, to encourage side shoots to form.
Water generously when the weather is dry, and add liquid fertiliser every two weeks. Cut flowers as required.
Cover tender new shoots with fleece on frosty nights, so they aren’t damaged.