Start preparing now for this year’s dahlias
As spring will be here in the blink of an eye, start preparing now for this year’s dahlias
It has been a year of ups and downs, with a good spring, followed by a hot summer, mild autumn and now lots of rain! But however the season treated you, it’s time to look ahead to 2020 and start preparations.
Make sure your greenhouse or storage area is clean and pest-free prior to putting fresh dahlia stock in for the winter. I use a sulphur candle when the greenhouse is empty and again once the tubers are in the greenhouse. This should kill off any aphids or spider mite that are left behind from your summer crops, plus any travelling in on your tubers.
Test that heaters and thermostats are working and safe. Don’t wait until the first cold night when your tubers are sleeping to find out they don’t work! Line the greenhouse or shed with bubble polythene to reduce heating bills.
The large bubble option is more expensive than the small bubble, but much more effective in the long term.
If you have any tuber stock still in the ground make sure it's lifted as soon as possible. With ground water so high, tubers left in may easily rot.
Wash off any excess soil as soon as they're lifted.
It's hard to remove or dry tubers with wet soil stuck around them. Place the clumps upside down on the greenhouse bench. If you don't have a greenhouse then any cool, frost-free place will do fine, such as a garage or shed. I normally have a fan circulating the air around which helps dry the soil off quicker. After one or two weeks you can turn the tuber and remove any remaining soil which should be dry by now. Any damaged tubers and fine roots can be removed cleanly with a knife or pruners, then apply a dusting of yellow sulphur to protect from mould. Where the days allow, keep the greenhouse or storage area well ventilated but frost-free. This can be hard with constant low temperatures or wet weather, but do your best as this will help the tubers from rotting around the stem.
Plants grown in pots if not moved in already should be brought into the greenhouse or shed. If the pots are saturated then it's best to remove the tubers. If they've been sheltered you can leave them to dry out naturally in the container, but remove some of the soil from around the stem.
Check your tubers regularly for signs of rot. If they look like they may not make it through
to spring, then the only thing you can do is to wake them up early. Place any precious tubers into some compost and put on a heated bench or in a spare room if you're allowed. Once awake the tuber can be grown on slowly and cuttings can be taken at the normal time.
Now’s also the time to order new stock. New varieties or those that are not the best keepers or propagators are always in high demand with the few specialist nurseries that supply pot tubers or young plants.
This may be a season with losses after such a wet autumn, so it's best to think ahead. The new giant ‘Louie White’ from Halls of Heddon is already in high demand as I am sure are many others. There’s work to be done outside, too. If the weather allows, try and do any digging on your plots as soon as you can. If you have a safe source of organic matter this is the time to add it. I dig in the tops off the dahlias and the straw that I used as mulch during the season.
If you can get well-rotted farm manure this is best applied to the beds where you intend to grow decorative and ball classifications. It's thought that rich soils can make cactus and pom types course, so use more sparingly on these areas.
Rotating the beds you grow the different types of dahlias in can be a good idea to allow you to improve the ground over a few seasons. Winter's also great for killing off pests and diseases in the soil and breaking down heavy soils, making it lighter work in spring. Once
done take a rest, with an occasional visit down to the greenhouse to check on tubers.
NEXT WEEK Snowdrops to provide a beacon of light in the garden on dull winter days