Dahlias in fashion

Varieties to plant and tips on keeping them happy and flowering

Sat, Mar 23, 2013, 00:00

In the way that some people remember their first kiss, I still remember the day as a young teenager that I fell in love with dahlias, after my mother brought an armful of their giant, jewel-coloured blossoms home from the local country market. Placed in a vase of water, the flowers glowed – a vibrant huddle of elaborately petalled blooms reminiscent of one of Renoir’s famous flower paintings. Floriferous, long-flowering, versatile and relatively easy to cultivate, even then it was difficult to understand why the genus had fallen so firmly out of fashion.

Now, of course, the dahlia is enjoying a much overdue renaissance, championed by gardeners such as the late Christopher Lloyd, a man who took a special delight in flouting the straitlaced conventions of “good taste”. The result is the ready availability of a vast selection of different varieties in every possible hue except blue (the RHS Dahlia Register currently lists 17,500), which are formally classified into 14 different groups according to their flower shape. Some, including the giant “cactus” type known as Pink Jupiter produce exhibition-class flowers of gigantic proportions, each bloom as large as a dinner plate. Others such as Jowey Mirella produce intricately arranged, spherical, black-red blooms a fraction of that size.

Now, while a good selection of stock is still available, is a great time to order the tubers – those swollen, sausage-shaped modified roots that the dahlia plant forms as a means of storing food during the dormant season, allowing it to explode into new growth each spring. You can either plant these directly into the ground from mid-April onwards, or follow the lead of experienced gardeners who give them a great head start (and guarantee much earlier flowers) by either chitting the tubers in a tray of damp compost somewhere warm and light (suitable for large clusters of tubers), or planting them in a container (usually a two-litre pot). This stimulates the plant into early growth, encouraging shoots to develop and bringing on flowering.

Kept undercover in a bright, frost-free spot such as a sunny porch or glasshouse (protected on cold nights with a layer of fleece), both chitted tubers and potted tubers can be planted outdoors from early May if given good night-time frost protection. If using the bare chitted tuber method, bury so that the crown of the plant is just above soil level. In both cases, take great care not to damage the brittle young shoots. Alternatively, plant outside after all risk of frost has passed. Always “harden off” soft growth by gradually exposing the plant to cooler temperatures.

Few people know more about the art of cultivating these vibrant summer blooms than nurseryman and champion grower Martin Lawlor of Lawlor’s Garden Centre in Durrow, Co Laois, who has been growing dahlias since 1970. A regular exhibitor/prizewinner at competitions including the Tullamore Show and the All-Ireland Dahlia Championships, Lawlor grows over 70 different varieties. While some gardeners are happy to let all their dahlias overwinter outdoors under the protection of a thick mulch, he lifts his best tubers each autumn – a practice that stood him in good stead in the extreme winters of 2009-2010, when fierce frosts destroyed other growers’ stock.

These tubers are washed, turned upside down and left somewhere cool, dark and frost-free to dry out before being encouraged into early growth under cover the following spring. Lawlor propagates up to 3000 new dahlia plants each year from cuttings taken in February/March, selling the young plants each spring/summer to Irish gardeners who come from all over the country to place orders. For exhibitions and competitions, his own favourites include Bryan Trefel and Kenora Valentine.

To get the very best out of your own dahlias this summer, give them full sun and a very rich, moist, but free-draining soil enriched with lots of manure, homemade compost and an organic fertiliser. Plant unchitted tubers outdoors deeply (15-20cm) from mid-April on, with the “eyes” pointing upwards, staking taller varieties at planting time to avoid later damage. Keep weed-free and deadhead flowers regularly. Hugely versatile, they can be grown as cut-flowers, in a mixed border, or in large containers. This year I’m aiming for a jewel-like contemporary effect, interplanting a mix of crimson, black-red, purple and fiery-orange cultivars alongside perennial grasses and airy perennials such as Verbena bonariensis. I can’t wait to see how it all turns out.

Plant sale
The Irish Dahlia Society is holding a dahlia tuber sale of many rare/hard-to-get varieties at today’s ISNA Plant Fair in St Anne’s Park, Raheny, Dublin, (10-4pm). Contact David Maloney at pdmaloney@eircom.net for details of other IDS events/membership.

The Tullamore–based firm Beechill Bulbs (bulbs.ie). For Irish-grown plants including some Irish-bred varieties, contact Lawlor’s (lawlorsfloristdurrow.ie) and Christopher White (flowersbychristopherwhite.com).