Delightful dahlias full of colour
Carnival-like striped dahlias beneath the late Elsie Morgan's teapot tree in Otaki. Photo: Vicki Price
By Vicki Price
If there is one plant that reliably provides sumptuous colour throughout late summer, it is the dahlia.
Once considered by some as a bit ordinary, nowadays there is a large range of colours and shapes to admire and they come in all sizes, from wayward tall to politely short and contained.
On a school trip many years ago in the height of summer, I was billeted by an Upper Hutt couple who were dahlia enthusiasts. Their garden was a full celebration of head-height plants with dinner-plate sized blooms.
There was careful picking on the day of a show and concentrated preparations in the kitchen. Almost perfect blooms had their stems snipped just so and then momentarily dipped in boiling hot water before being placed in buckets of cool water for transport. It was a serious but beautiful affair.
The Levin Dahlia Circle has just hosted its 75th Jubilee National Show. Clubs
around the country are holding shows throughout the dahlia's summer flowering period.
For sheer beauty and ease of maintenance, dahlias are one of those plants hard to beat. Apart from staking and tying up tall straggly flowers, they are relatively easy to grow. They can be left to get on with their display each year or be given attention to get maximum effect from their generous blooms.
Dahlias grow from a tuber and these can be bought from shops or dahlia clubs for planting late October. Garden centres usually have miniature cultivars for sale and these make for beautiful potted plants or for borders en masse.
Bedding dahlias are often seen in council garden displays where they are treated as annuals and dispensed with once flowering is over.
Tall dahlias can reach well over your head and produce large blooms reminiscent of some varieties of sunflower.
Tree dahlias are something else again and are a delightful tall shrub option that blooms pretty pink flowers so familiar as their shorter cousins but quite novel to see in a tree.
It's mostly about the flowers with dahlias but there are some with dark mauve foliage and these can be used to bring a little drama as a focal point against a paler background in the garden.
Being the national flower of Mexico, you can imagine these bright sparks like a sunny spot in the garden to live, but they will also grow well in partial shade.
Before planting a dahlia tuber, (after Labour Weekend when the soil has warmed up and frost danger is past) ideally dig in some compost and place a stake in the ground right away. This ensures the plant has good nutrients in which to grow and won't risk damage to the tuber by a later staking.
The National Dahlia Society recommends placing tubers in the ground about 12 centimetres below the surface on an angle with the sprouting bit pointing upwards for drainage so that heavy rain or excessive watering has less chance to cause rot.
You really don't need to water much until the plant has grown roots to drink and a good mulch will help keep moisture in and the soil cool.
Dahlias, like other plants, can be afflicted with mildew and one way to help prevent this is to water in the morning rather than at night, so that the leaves have time to dry before the cool of the evening creates conditions for mould to grow. If the plant gets all mildewy late in the season, it probably doesn't matter as the plant is about to die back for its winter hibernation anyway.
For a bushy plant that produces plenty of flowers, pinch out the main growing tip once it is about 20cm tall and wait to enjoy the summer show. If you want to, you can lift and divide the clumps of tubers come winter time - they're generous in their proliferation too.