8 December 2014
Arne has been growing dahlias at Allt-y-bela since he first started creating a garden here over seven years ago. They provide great late season colour, come in a huge range of colours and forms and are perfect for cutting. Dahlias have become an integral part of many late summer garden schemes as their popularity has been restored after a fairly torrid time in the eighties and early nineties.
Dahlias are native to Mexico and Central America and were an important crop for the Aztecs who both cultivated and harvested them from the wild. They ate the tubers, used them to create medicines and used the dried hollow stems as water pipes. The cultivation of dahlias as a crop declined after the Spanish conquest, and an attempt to introduce them to Europe as food failed, people preferring the potato instead. Today the dahlia is the national flower of Mexico.
Dahlias are half-hardy tuberous perennials, meaning that the top growth will be killed off by frost in the autumn but that the plant will store its energy in swollen root-type structures until late spring when they will put on top growth again. In most of the UK dahlias can't be relied upon to survive outside over winter. That might sound like an overly qualified statement, and intentionally so! Many people have methods for keeping dahlias outside over winter but I think it is fair to assert that those lifted in the autumn and started out in pots in the spring flower much earlier in the season than those left in the ground.
The best way to buy dahlias is as tubers in the spring, they are usually available from garden centres but there are also some great online and mail order bulb companies which often stock varieties you may struggle to find in the shops. I recommend planting them into large pots in a cool greenhouse or poly tunnel around Easter. Keep them in their pots in the greenhouse until after the last frosts - usually the end of May - after which, plant them out into the garden. You may find that the growth is quite soft at this stage so the plants might need staking. Dahlias tend to put on a lot of top growth and can end up tumbling other plants unless they are well staked. Staking is always best undertaken before the plant needs it, I'd always advise setting up the staking when you first plant the dahlias out.
The only thing left to do now is to keep cutting the blooms or deadheading them until the frosts come along and knock them back again. It's worth noting the difference between buds which are about to break into flower and those which are over. It is sometimes difficult to distinguish unless you know what to look for. The flat-topped button like buds are those about to break and the long conical looking buds are those which are over and need to be removed.
Words: Steve Lannin, gardener at Allt-y-bela
Photographs: Britt Willoughby Dyer
It's best if you can leave the cutting back and lifting of the dahlias for as long as possible. The plants will naturally start to build up energy reserves in their tubers as the days shorten and the cold begins to bite. Once the frost has blackened the stems I cut them back to the ground before carefully lifting and washing them. Once they are washed they should be labelled and left to dry for a couple of weeks, somewhere frost free but not too warm. Once you are sure the tubers are dry and clean - to help prevent rotting - you can store them for the winter. The tubers need to be stored somewhere frost free and safely away from pesky rodents who will be only too happy to tuck in, even if you have passed on eating them yourself! I tend to store them in straw, but you can store them in open trays or in dry sand if you prefer.
Whether you are lifting and storing your dahlias now, or considering adding some to your garden in spring, dahlias are fantastic garden plants and are available in colours, shapes and sizes to suit all tastes.