It's always been a sun bunny, first cultivated by Aztec botanists in Mexico. Spanish explorers discovered it in the 1500s and brought it to Europe, where it became a favourite of the working classes. It attracted even more attention in the mid-1800s when a blight wiped out the potato crop in France and the French thought its tubers might be a good spud substitute which, as we now know, they weren't. It's unlike the French to make a mistake about food but they redeemed themselves by noticing the dahlia's flowers and foliage and it was on its way to worldwide acceptance among we common gardeners.
Planted in late spring, it produced beautiful blooms in late summer and a garden dancing with white, yellow, orange, pale pink, lavender, and red is a heart-lifting sight.
The flowers range from 3cm to 15cm across and can be tight balls or very open, single or double, with petals that are flat, curved, or rolled into tubes. The dinner-plate types can grow a full metre high in just a few months. The American Dahlia Society (www.dahlia.org) lists 20 classes.
After planting, water dahlias lightly. Roots and sprouts will form quickly in warm soil and buds will develop in early summer.
When the plants have finished flowering for the season, don't cut the foliage back: the leaves will absorb sun and collect nutrients to provide nourishment for next year.
If you decide to dig up your dahlia tubers at the end of the season, you'll discover your plants have been just as industrious under the ground as on top of it. You'll find clumps of tubers to divide. Let them air dry for several days and store in paper bags or boxes filled with peat moss.
Replant in spring with 5-10cm soil above them and between 30-60cm apart depending on their mature size. Look for the side of the tuber that appears to have the most growing points - they resemble the eyes of a potato. It's best to plant with the eyes facing up but chances are your dahlias will grow anyway.