IT’S NOT TOO LATE TO ENJOY FLOWERS FROM THE POTTED VARIETIES AND THE BRIGHT BLOOMS WILL LAST FOR AGES IN A VASE
Around this time every year potted dahlias become available at garden centres and I am reminded that I should have sourced the tuberous bulbs to plant out last spring.
It’s still not too late to enjoy a month or so of remaining flowering time from the potted varieties, and later store the bulbs ready to plant next spring.
Gardeners in the know and with better timing than me, will have ordered online from the growers. Special forms and new releases can be bought as single bulbs, and the more common forms are often sold in mixed multiples.
Dahlias, which originate in Mexico, have long been a favourite flower of mine, a reminder of a gardening childhood. These stunning flowers first found their way into Spain in the late 18th Century.
Spanish botanist and later director of Mexico’s first botanic garden Vicente Cervantes was on expedition in Mexico (then New Spain) and found several species with single flowers. The seeds were sent to Jardin Botanica in Madrid where the Genus was named for Anders Dahl, a Swedish botanist.
Dahlias also have a rich Aztec history that predates Spanish arrival in South and Central America. The tuberous roots of the wild native dahlia were a food source and the hollow stems were used as pipes.
There are around 30 species and thousands of cultivars to choose from. Most will select by flower form – they come in a variety, including tightly packed, slightly rounded petals of the perfectly formed pompons and ball forms.
The large open cactus forms have reverse pointed petals, which result in a spiky look, while the flatter and slightly open flowers of waterlily forms definitely resemble their namesake.
The smaller flowers of Collarette dahlias (pictured) are extra special because of the flat outer ray of petals and the inner central ray of shorter petals that are often a contrasting colour. The deep burgundy foliage forms introduce an immediate contrast and are a perfect foil for the brilliant coloured flowers.
Once planted, dahlias require staking, and the divided foliage will soon cover the stake. Plant dahlias near vegetable beds and fruit trees as they are great to attract bees needed for pollination.
Most can be grown in pots and then rested until the next season. They are wonderful, long-lasting cut flowers, the taller growing forms for longer stems or the shorter pompons and Collarettes for glorious posies.
Like many great flowers that have been bred extensively, there are a number of pests that need monitoring. If affecting plants badly they will require control. Look for products based on low toxin soaps for mites, natural soil bacteria Bacillus thuringiensis for caterpillars, and the bacteria Spinosad for leaf miner and thrips.
Natural bacteria break down quickly in sunlight so it’s best to spray later in the day for the best results. Organic gardeners recommend egg shells and sawdust to impede snail movement.
I may have missed the perfect timing for planting tubers, but I plan to shop for potted dahlias for the veranda this week, and mark my calendar as a reminder to order my bulbs online for next year.
Kate Heffernan is a horticulturist, educator and honorary life member of Friends of the Gold Coast Regional Botanic Gardens. You can listen to her radio show Garden Talkback on ABC 91.7FM. Details at kateheffernan.com.au