Many of us have the tall border Sedums such as S. spectabile in our gardens – they are extremely reliable, very forgiving, tough as old boots, capable of withstanding drought, poor soil, disruption, digging dogs and general neglect, and they still come up with flowers every year. Best of all, they are a magnet for butterflies and insects in the summer, and the birds enjoy clearing the seeds out from the dying flat-topped flowers in autumn.
My personal favourites are the dark purple-leaved varieties: there's a nice one called S. telephium ‘Atropurpureum’, with lovely purple leaves, and dark pink flowers: and even better is the cultivar 'Purple Emperor' whose leaves are really dark and shiny, lovely!
Regardless of their foliage colour, at this time of year they are looking sad and horrible – all dead and brown on top, and many of the upright stems have been damaged by wind and weather – but the new growth is already starting, so now is the perfect time to get out there and cut them down.
If you leave it much longer, these buds will start to grow, and before you know it, it will be impossible to get the old stems off without damaging the new – so grab your secateurs and get out there now!
It's really easy to do: just follow each dead stem down to the base, and carefully snip it as close as you can to the new growth, taking care not to damage those new leaves. Don't pull out the dead stems, as you are likely to uproot small sections of the plant if you do so: snip them off neatly, as low as you can.
While doing this, if you find any really dead, blackened stems from previous years – possibly when you didn't get out in time to cut them very short, and had to cut them at ankle height – pull gently on them, and with luck they will come out cleanly. This reduces congestion, and allows better air circulation at ground level, which helps the plant to avoid mould and other diseases.
The seeds should all be long gone by now, so the parts you remove are ok to go in the compost – and if you should, accidentally, break off any parts of the plant that are starting to grow, don't waste them: snip off the dead top stem, and pop them into small pots of compost, or even just push them into the ground nearby. Many of them will happily grow on, and in a few months you will have strong new plants to give away, to swap, or to add to the garden.
The photos above show a good sized clump with the dead brown flowers hovering above – this is what most people have, at this time of year. (Can you see how far I've got with clearing up the bed?!) The other photo is the “after” picture, showing what you should have left.
One final question – the common name for S. spectabile is Ice Plant: why? why? The foliage is green, the flowers are pink, where does the “ice” come into it? Mind you, “Stonecrop” is not exactly an accurate descriptive name, either! Even worse, S. telephium is, incomprehensibly, commonly known as “Orpine”. Commonly known? Do you ever refer to this plant as Orpine? I just call the whole lot of them Sedums and leave it at that!