Everything we wanted to know about growing dahlias was explained to us by Kim O’Brien, our November speaker. Kim has been growing the flowers for over 25 years and has 250 varieties on her plot. As well as a florist, garden designer, speaker for the BBC Gardener’s World, columnist for Amateur Gardening magazine, she has many more strings to her bow.
Dahlias originated in Mexico and were introduced to the UK over 200 years ago as an edible crop. The tubers can be cooked like a potato but taste a bit like celery. The leaves are peppery and be used in salads. Petals can make any dish look extravagant when sprinkled on top. There are so many different classes making it quite challenging when exhibiting in shows. The examples Kim gave were cactus, decorative, pompom, ball, single, collarette, anemone, to name just a few. All dahlias are good pollinators but obviously the open blooms are better. A good tip we were given is to leave the compact blooms on the stem a little longer for the central petals to open and provide a good source of nectar for the insects.
The big question is: do we leave the tubers in the ground or lift. Dahlias like a free draining soil and if left in the ground mulching is important. There is a particular time that lifting is recommended and that’s after a couple of frosts. The cold spell sends a message to the tubers to become dormant. This is becoming a bit of a problem when Autumns are becoming milder. Lifting is not fool proof that all the tubers will survive. Washing is not necessary, invert the tubers to drain and place in a cool frost free in sand, sawdust or shredded paper. Examine regularly for mould and sprinkle with cinnamon, which is an effective fungicide.
There are 2 methods of propagating, splitting the tubers and taking cuttings. When splitting tubers, it’s important to have the top of the neck intact as it is the growing point. Cuttings should be taken when they are just emerging at the base. Blooms are bigger and stronger when grown from cuttings as opposed to tubers. To get bushier and stronger plants Kim recommends cutting back at the start of the season, this will delay the flowering by a few weeks though. We were also given advice on feeding regime and how to produce bigger blooms by removing lateral buds. The evening ended with members purchasing tubers brought in by the speaker.
