Aeonium aboreum zwartkop
Easily grown impressive architectural plant. For £5, current minimum plant size is height 24cm, span 12cm.
Aeonium zwartkop. Possibly my favourite plant. Looks good either bedded out as rosettes or as large specimens in clay pots. I plant 3 to a large clay pot about 45cm diameter and sometimes singles in smaller pots 30cm dia. always clay with a soil based compost because when tall they are top heavy and they need the extra stability. Very easy to look after. Need to be frost free but here at the nursery I have had the leaves frozen, thawed the plants out gently and they remained perfect, so I would say they are good down to +1c but I would be concerned about them being outside unprotected below +3c. Full sun required for the blackest leaves. Plants will go a bit green in winter but soon colour when the sun light has some warmth in it. A little water in winter to avoid excessive leaf drop, in summer plants can take frequent watering but will get by watered once a week. Leaves may flop in extreme heat, slightly floppy or excesive lower leaf loss when in desperate need of water. Plant in free draining soil. Plant naturally grows upwards and looses lower leaves. Plants best left to branch naturally which they all do but branching can be encouraged through rubbing or cutting off and rooting top and allowing old stem to produce shoots. Grows to about a metre tall but old plants may get untidy in which case propagate and start over. May suffer from vine weevil or rotting off through over watering which will topple the plant. Same remedy, cut top rosette and root.Very difficult to loose the plant in my view!
Flowers are yellow, produced in early spring, and the plant must be a few years old to flower. Flowering rosette dies after flowering. Grow outside in frost free months in full sun or of course grow under cover in full sun for the best coloured foliage.
The photo below shows a group of small zwartkop in late March. They are very dark, the glossy leaves reflecting light.
The bottom photo shows the plants colouring in early March. Plants sent out often have a green centre like this after being in a box during transit, but soon turn dark in sunlight.