Belle of Barmera is a decorative dahlia with deep burgundy-purple flowers — named for the wine-growing region of Barmera in South Australia. The blooms open from tight, clustered buds on dark mahogany stems, the colour intensifying as the petals unfurl. Like all dahlias it is slow out of the ground: plant tubers after last frost with the eyes facing up, and resist watering until the first shoots appear — tubers rot before shoots emerge if the soil is cold and wet.
Pinch the growing tip at 12 inches to force branching and multiply stem count. In Zone 6b lift the tubers after the first killing frost, cure for a week in a dry spot, then store packed in barely-damp vermiculite at 40–50°F. The deep colour makes it a natural partner for late dahlias, Japanese silver grass, and the last zinnias of the season.
Powdery mildew
White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.
Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.
Botrytis (grey mould)
Grey fuzzy mould on petals and stems, worst in cool wet conditions.
Remove affected parts immediately. Improve air circulation. Avoid overhead watering. Apply copper fungicide if severe.