Dahlia are tuberous rooted perennials with pinnately divided leaves and showy flower-heads, double in many cultivars, in summer and autumn
Small-flowered Decorative dahlias have fully double flowerheads 10-15cm across, with broad, flat, blunt-tipped ray florets
'Grenadier' grows to 1m, with dark foliage and double flowers 9cm across, the broad, overlapping florets bright red, darker in the centre