Dahlia
Dahlia pinnata
Show-stopping tuberous perennials that provide a spectacular display of colour from mid-summer right up until the first frosts. Ranging from enormous 'dinner plate' blooms to intricate pompoms and open-centred varieties that bees adore, they are a staple of the late summer UK garden.
Growing Guide
Step-by-step instructions for growing Dahlia
Planting Calendar
Growing Guide for
Change the guide to see different planting timelines and tips.
The most reliable method for UK gardeners. Starting tubers in pots under cover gives them a head start and protects the tender new shoots from slugs and late frosts.
1 Pot Up Tubers
About 6 weeks before the last frost, fill a pot halfway with peat-free multi-purpose compost. Place the tuber in the pot with the old stalk stump facing up. Fill with more compost, ensuring the crown (where the old stem joins the roots) is just below the surface. Water lightly and place in a frost-free greenhouse or sunny windowsill.
2 Pinch Out Tips
Once the new shoots have formed about 3 to 4 pairs of leaves, pinch out the growing tip just above a pair of leaves. This encourages the plant to become bushier and produce more flowers, rather than one tall, spindly stem.
3 Harden Off
Before moving them permanently outside, acclimate your dahlias to outdoor conditions. Move them outside during the day in a sheltered spot and bring them back in at night. Do this for 7-10 days to toughen up the foliage.
4 Plant Out
Once all risk of frost has passed in Woodhouse Down (usually late May to early June), plant your dahlias into their final positions. Dig a hole and plant the entire rootball so the top is level with the soil surface. Space plants apart. Insert a sturdy stake now to avoid damaging roots later.
5 Support and Protect
Tie the main stem to your stake using soft twine. This is also the critical time to apply slug protection, as slugs love young dahlia shoots. A barrier of wool pellets or organic slug control is highly recommended.
6 Feed and Water
Dahlias are hungry plants. Once flowers appear, apply a high-potash liquid feed (like tomato fertiliser) every two weeks. Water thoroughly once a week during dry spells, aiming at the base of the plant.
7 Deadhead and Harvest
Cut flowers regularly for the vase to enjoy indoors—this actually stimulates more blooms! For garden display, remove spent flower heads (the pointed ones; round buds are new flowers) to extend the flowering season right up to the first frost.
8 Lift Tubers
Once the first frosts have blackened the foliage, it's time to lift the tubers for winter storage. Cut the stems down to , carefully dig up the clump, remove excess soil, and dry them upside down for a few weeks before storing in a cool, frost-free place in sand or vermiculite.
Related Plants
Explore similar plants you might like
Cucumber
Cucumbers are fast-growing annual vines that produce crisp, refreshing fruits and thrive in warm conditions. They come in indoor (greenhouse) varieties and hardier outdoor (ridge) varieties. Greenhouse cucumbers are usually all-female and grown under cover for seedless, tender fruits, while outdoor cucumbers are rough-skinned ridge types that grow in open ground and require pollination. All cucumbers need full sun, rich soil, and consistent moisture for a prolific summer harvest.
Garlic
Garlic is a hardy, sun-loving bulbous vegetable from the onion family, grown for its pungent cloves used in cooking. It’s easy to grow in a warm, well-drained spot and needs minimal fuss – plant individual cloves and they will develop into full bulbs by the following summer. Most garlic varieties require a cold spell over winter to form good bulbs, so in the UK they are generally planted in autumn. There are two main types of garlic: hardneck and softneck. Hardneck types produce flower stalks (scapes) which should be removed, and their bulbs have fewer but larger cloves (they store for around 4–6 months). Softneck types have more, smaller cloves and rarely bolt; they also store for longer, often up to a year.
Basil
Basil is a fragrant, tender herb whose leaves are a staple of summer cooking. Native to tropical regions, basil is treated as an annual in temperate climates like the UK because it cannot tolerate frost. It thrives in warm, sunny conditions and can be grown in garden beds or pots for a steady supply of fresh, flavourful leaves throughout the summer.