Frequently asked questions
■ What’s the difference between a ball dahlia, a cactus dahlia and a pompon? DAHLIAS come in a huge variety, so they are classified in groups according to their flower shape and size, although categories overlap a little.
Pompon dahlias have small, tightly packed, spherical blooms, usually about 2in (5cm) across, with individual florets rolled into a tube and flared at the mouth.
Ball dahlias are similar to pompons, but larger. Small ball dahlias are 4-6in (10-15cm) across, miniature ball dahlias are 2-4in (5-10cm).
Cactus dahlias have petals rolled into tubes, giving a very spiky look. Here, I include some miniature cactus varieties less than 4in (10cm) across.
■ Will my dahlias flower for longer if I feed them?
YES, Feed them every two or three weeks from planting in May until September. A tomato feed is ideal. Keep the plants moist, but not waterlogged. If the plants dry out the flower stems will be shorter, the flowers will be smaller, they will fade more quickly and flowering will finish earlier in autumn.
However, the most important thing is deadheading. Either pick the flowers for the house regularly, or snip off the old flowers as they fade to prevent them making seeds.
■ How can I keep my dahlias from getting frosted and prolong their season? PROTECTING dahlias from the first frosts of the autumn is a sure way of extending the flowering season. In fact, it is often the early morning sun that does the damage, as foliage with frost on it warms up too quickly. Planting in a site that is protected from the early sun, and from easterly winds, is a big help.
Also, if frost is forecast, cover the plants. I use old bedsheets – beg some off friends if you don’t have any. Fleece is a good, but more expensive, alternative. In early evening simply lay the sheets over the plants – it’s much easier with help. Then remove them, carefully, the next morning when it warms up.