Dahlia 'Tartan'

Take cuttings from tubers which have started into growth in a greenhouse or frame from late winter onwards. The ideal temperature is 16C. When the young growths are 3 inches long, remove them from the tuber with a sharp knife making sure you leave a 'stump' for new growth to form. Remove the lower pair of leaves from the cutting and dip in rooting powder. Insert the cuttings around the edge of pots of loam, peat and sharp sand in equal measures. Water thoroughly and place in a propagating frame at 16C. Keep moist and shade from sunlight. After 3 or 4 weeks, once rooted, pot singly in 3 inch pots until they are wanted for planting.

Plant the un-sprouted tubers in early spring, at least 4 inches deep. Plant rooted cuttings and sprouted tubers during the late spring but if the weather is cold and wet, wait for conditions to improve.

Border dahlia will flower from mid-summer through to autumn or the arrival of the first frost. The season can be prolonged by regular dead heading.

Division of the tubers is the simplest method and will produce plants the same as the parent. In mid-spring, divide the tubers with a sharp knife ensuring that each division has an undamaged eye. Dust the cut parts with flowers of sulphur to prevent fungal attack. They can now be planted not less than 4 inches deep.