Dahlia has become something of a byword for cool of late, bolstered in some measure by flower power gurus, Sarah Raven, Blue Carrot, the fabulous Erin at Floret and a whole slew of other luscious flower champions and I like many have become enamored, nay completely overtaken by an unexpected greed for them in almost every colour and form. Well that’s not strictly true white and yellows aren’t really on the radar though a few lush ones have made it through vetting.
In the last 5 years I have dabbled with Dahlia, I grew a whole range from seed, Spiders, Cactus, Pompom, Dinner plate. You know the random seed sorting left overs called “Mixed Pompom” or “Mixed Bishop’s Children” and I’ve had some success. The Bishop’s children were surprisingly varied with some exciting colors emerging. Of course Bish of Landaff babies were dominant – yawn – but so too some rich pinks and peachy oranges too. A few additional tubers in deep Maroon/Blacks added to the mix but nothing too extensive as I was a bit overtaken with Iris maintenance and space limited by the same.
Last year I lost 3 or 4 of the blacks, they simply couldn’t survive the wet in the ground. I leave mine firmly in the ground, well mulched and planted with plenty of grit in the mix. So last year I restocked with more interesting options forgetting they would be flourishing when I was flat out at Tatton and not giving a hoot about anything non-show garden related. Mono focus is good for show gardening, not so good for multi-focus at a distance. A very kind family member baby sat the 12 huge pots, lavishing them with food and water and cutting the odd bloom.
THIS year however I have really been bitten. scaling back the Iris and pondering possible revenue avenues from blowsy Dahlia I have acquired around 25 more varieties from a wide range of sources – Wilco’s, Wyevale, Frosts, Crocus, Sarah Raven, Waitrose and Halls of Hendon. Along with last years collection and my Bish Babies there are around 40 going in the ground for a great display of colour.
It is surprisingly difficult to get some of the more unusual cultivars, especially ones seen at Floret which makes me think a bit of hybridising might not be a bad idea, how hard can it be? if I can manage with fiddly Iris bits surely a Dahlia will be a doddle? famous last words. Of course some bright spark will import a whole batch next year from the USA, or maybe they are already building stocks!
Dahlia could have had a very different life, in their native county (Aztec Mexico) the underground tuber was consumed much like a potato as a food crop, it never really caught on in Europe and I would strongly suggest not consuming modern day ornamental varieties! just in case. The Genus is a member of the Asteraceae family related to Sunflowers, Asters, Chrysanthemums, Daisy and Zinnia. Bushy, fleshy leaved herbaceous perennials dahlias come in a rainbow of colours but no true blues. The tubers cannot withstand freezing and thawing so except in the south of the UK they are not hardy to be left in the ground and need lifting once the first frosts blacken the foliage. Lifting them is simple, dig them up trying not to spade through the valuable tube, clean them off cut off all the foliage, I usually leave a stem of about 5cm so I know which way is up the following year, best practice is to then dry them out for a month or so, stem down so it latent moisture doesn’t rot the tuber and then place them in slightly damp compost, well more not totally dry than actually damp, in a frost free place, crown to the top over winter. A garage, a sturdy garden shed a back cupboard under the stairs wherever it is it MUST be frost free, cold is fine but no freezing or you’ll end up with mush for tubers come spring. Bitter experience speaking there!
Getting them going the following year is a nerve wracking experience, you want to get them sprouting early but you don’t want them to catch the frost. Now if you have oodles of potting shed, glass house or garage space to get them started in 10ltr pots I am in total envy, if like me you have none of the above you will learn to listen avidly to the weather, sunny cloudless spring days bode for frosty nights, wind can help blow it off but I prefer to not risk it and either cover them up with fleece, packing them close together in some sort of loose shelter or if they’ve managed to claim space in the cold frame I close the lids of that. It really pays to know where the frost-less pockets are in the garden for this game of spring chicken. i another garden we had an old scotts pine under which there was never frost even if the rest of the garden sparkled, slight rises in level can be frost-less too. Get out on a frosty morning to see whee yours are.
Once they start sprouting you can either take cuttings, pot them on into a multipurpose compost making new plants or plant out the whole tuber and it’s shoots, though I tweak off more than 3 shots to ensure sturdy growth that doesn’t exhaust the tuber. Like sweet peas they;re greedy so feed their planting hole with a well rotted manure or compost and as they begin to grow away in June feed a nitrogen feed – for the foliage – then in July through to August start feeding with a high potash feed (e.g tomato food) to boost flowering but also to boost the tuber for next year. I knock in stakes on a grid system and use wide pea netting, at 30cm and 60cm high, to ‘stake’ the patch. My site is windy so the plants hunker down a bit making them sturdier but I like to know they won’t flop from too much food or water.
I cut flowers long, taking some foliage with each cut but aiming to leave the plant with plenty of foliage for the plant to feed itself. Once they’re hit by frost I take down the foliage and if they’re staying in the ground I pile straw over them and 10cm of compost per tuber group.
Can you recommend your favorites? and who has supplied you with great tubers?