There are few sights more captivating than a colour-themed dahlia border in full throttle. And what better way to view them in all their myriad shapes and hues than at a dahlia festival? From village shows to open gardens, stately homes to nursery fields, there are dahlias blooming everywhere this month. The National Trust’s Anglesey Abbey in Cambridgeshire has a particularly memorable dahlia border that begs a panoramic photo when you visit; similarly, Kelmarsh Hall in Northamptonshire has a dahlia collection to die for; and the National Dahlia Society is holding its own dahlia show at RHS Garden Wisley in September, complete with judging and demonstrations. Dave Gillam, Chair of the Society, has plenty of good advice on how to keep dahlias looking fabulous.
“Generally the only thing dahlias don’t like is shade,” says Dave. “So, start by picking a sunny, open site. In winter, they can cope with cold and they can cope with wet, but not at the same time. So, if you have heavy soil but don’t want to lift them in autumn, the best bet is to create a slight mound at the bottom of their planting hole, so you’re raising the tuber above the natural water level. Add grit and plenty of organic matter when you plant, then in winter, simply cover the crown with straw as an organic mulch.
“In garden situations, it’s worth trying to leave them in the ground over winter. If they survive that first year, when the plants are at their smallest, you’ll have them for life. It’ll save an awful lot of time and effort lifting and storing them. Besides, many dahlias are lost through improper winter storage – for instance, don’t put them in plastic bags or leave them in wet compost.
“If you do decide to lift your tubers over winter, wake them up slowly in spring. Don’t plant them out until they’re showing actual signs of growth. Instead, plant the tubers in a pot on a warm windowsill and wait for them to show signs of life. Plant them out after the last frost and they’ll be in flower as early as June.”
Dave has being growing dahlias since he was 10 and regularly competes in the National Championships against around 200 other serious exhibition growers. “My secret is to give the plants what they need before they need it,” he says. “If they’re showing signs of stress it’s too late. You have to keep the soil constantly moist, control the number of flowers and keep their stems well supported: I use three canes in an inverted pyramid to give the flowers plenty of room.
“The hardest thing is getting them to flower at exactly the right time for exhibition. It’s a very concentrated effort – I grow about 460 dahlias on my allotment and I’m not allowed a hosepipe, so all the watering, as well as the weekly feeding, is done by watering can. But then, this is a Mexican plant that stores moisture in its tubers, so it can take pretty hot, dry conditions.”
Dave Gillam's Top Tips for better blooms
• STOPPING/TOPPING This is the act of removing the growing tip when the plant has 3-4 pairs of leaves (left). This makes for a stronger, bushier plant, triggering the next 6-8 shoots lower down the stem to start into growth.
• SIDESHOOTING This is when you remove the sideshoots lower down the stem to strengthen those that remain, so each stem only carries one main bud and flower.
• DISBUDDING This technique involves removing the ‘wingbuds’ on either side of the central flowerbud to make more space for the main flower, allowing it to reach its fullest potential size.
WHERE TO SEE DAHLIAS
ANGLESEY ABBEY Quy Road, Lode, Cambridgeshire CB25 9EJ l Dahlia displays from end Aug to mid-Sept. Adults £15; NT members free. 01223 810080; www.nationalturst.org.uk
THE SALUTATION Knightrider Street, Sandwich, Kent CT13 9EW l Displays, talks and demos. 15-16 September, 10am-4pm. Adults free. 01304 619919; www.the-salutation.com
CHENIES MANOR Chenies, Rickmansworth, WD3 6ER Rare and unusual cultivars to buy. 27 August, 2-5pm. Adults £6. 01494 762888; www.cheniesmanorhouse.co.uk
KELMARSH HALL Kelmarsh, Northampton NN6 9LY Tours, demos and dahlia clinic.
2 and 16 September, 11am-5pm. Adults £10. 01604 686543; www.kelmarsh.com
AYLETT NURSERIES North Orbital Road, St Albans AL2 1DH l Field trials and exhibition. 8-16 Sept, 10.30am-4.30pm. Adults free. 01727 822255; www.aylettnurseries.co.uk
NATIONAL DAHLIA SOCIETY SHOW RHS Wisley, GU23 6QB Exhibits and competitions. 4-7 Sept, 9am-5pm. Adults £14.50; RHS free. 01483 224234; www.rhs.org.uk