At the beginning of April, a headline to an article in one of the national dailies read, 'Chelsea Flower Show goes dry as traditional blooms take a back seat' and succulents were certainly prominent in the show gardens this year as the hosepipe ban was expected to be long-term. Things may have changed on the weather front but succulents are still a great addition to our gardens as they are perfectly adapted to long periods of drought. Over millions of years they have evolved a rain-collecting system with swollen stems and leaves as well as widespread shallow roots which seek out moisture. Many of these plants drop their leaves in prolonged periods of drought to reduce water loss and will photosynthesize using cells in the outer layers of their stems. The Euphorbia genus, the largest in the world, has myriad succulent forms dominating the landscape in parts of Africa, some of which reach enormous proportions and resemble cacti. We obviously tend not to grow many of these in our temperate region but with a cool greenhouse the enthusiast can certainly grow many succulent euphorbia and in particular, those from the Canaries. The sorts of succulents we can access more easily would be plants such as the sedums. And what fantastic garden plants these are. Look at catalogues from good nurseries such as Cotswold Garden Flowers (which is entertaining reading), or Marchants Hardy Plants over at Laughton, Sussex. Bob Brown at Cotswold Garden Flowers lists nineteen varieties alone including the delicious Sedum 'Purple Emperor' with its rich, dark foliage and red flowers. S. 'Purple Emperor' was spotted by Graham Gough of Marchants Hardy Plants in his parents' Sussex garden and of course he lists it in his wonderful catalogue.
Add a bit of grit when you are planting sedums out and don't bother improving the soil. If you do grow them on enriched soils the taller varieties can split and can topple over. If this happens, it's worth giving them the 'Chelsea Chop' in May. You'll lose the flowers but the plant will clump up nicely. The joy of sedums is that many of them can cope with dry shade; they are pretty well bomb proof, butterflies and pollinating insects absolutely love them and their flower heads are superb throughout the winter. Actually hoverflies are particularly keen on sedums and as they predate greenfly, these are pretty eco friendly plants. In the same family, Crassulaceae, are the sempervivums, also known as houseleeks or Hen and Chickens. You could get rather addicted to these. Basically they have a rosette of leaves in every colour and form you can imagine. Some of the leaves have silvery hairs in different lengths on their leaves and there are varieties which look as if they are covered with a silvery cobweb. They come from mountain regions so most can cope with extremes of temperature. The most important criterion for successfully growing sempervivums is a well drained site or pot. It is not necessary to feed them but a little slow release fertiliser does no harm. As they are monocarpic plants, once the rosette has flowered (lovely, many petalled, star-shaped flowers) it dies off, but the plant produces many offsets in the summer. Just separate the young offset from its parents once it has started developing its own roots and pot up or plant out. Grow in a gritty mix and re-pot fairly regularly. They don't seem to mind a little root damage to the extent that if you remove some of the old roots they do particularly well.
Aeoniums are succulents from the Canaries and Madeira, Morocco and Ethiopia. Aeonium arboreum and the dark form, Aeonium arboreum 'Schwartzkopf' in particular, is the one most commonly available in the UK. It is a really nice thing, very architectural in form with dark glossy leaved rosettes. Once the plant gets large it'll flower (small yellow flowers) and then die off but not before it makes new rosettes which can removed from the parent, potted on and kept for the next season. Aeoniums can't be left out in our winters but they are well worth growing. Bob Brown suggests keeping them bushy by 'taking the eye out with a sharp knife' as they do tend to get naturally tall and leggy. And then there are the echeverias. These come from a completely different part of the world, from Mexico and South America, and their rosettes are formed from both fleshy leaves and in some species, waxy leaves. Like the sempervivums, their leaves can be hairy. Their needs are much the same as the houseleeks, being in the same plant family, and they too are easy to propagate in that an individual leaf will root easily and give you more plants. They are very much half hardy to tender but such good plants to grow and as with all these succulents, just give them sunshine and a well drained medium and you will not have to water them every five minutes. They come in lovely leaf colours. E. 'Black Prince' has, as the name suggests, very dark red leaves and dark flowers in August and onwards. I particularly covet E. 'Mauna Loa' as apart from having leaves with a crinkly edge, its rosettes are in varying shades of 'orange, pink, grey, green and brown'. And again to add a bit of architectural 'oomph' to your garden, the agaves. They are not hardy but grown in pots they can be dragged into a light shed or garage for the winter until the worst of the frosts are over and then the whole exercise can be reversed and they can come out into the garden again. Unfortunately they don't reach the stunning proportions of those we see down near the Mediterranean. In ideal conditions, Agave americana can reach heights of up to two metres and 'Marginata' is a lovely thing with yellow margins to the leaves. The tips of the agave's very stiff, fleshy leaves are cruelly spiked, an adaptation in the wild to fend off predatory animals but they are worth growing for their sheer dramatic looks.
Sue Whigham can be contacted on 07810 457948 for gardening advice and the sourcing and supplying of interesting garden plants.