Quick ‘root’ to propagation
The summer herbaceous perennials are coming back! Their tender new shoots are reinvigorating our borders and announcing the arrival of longer days.
They also, however, provide a unique opportunity to propagate more plants.
We’ve been relishing the chance to take basal cuttings on the RHS courses. Many summer-flowering herbaceous perennials die down to a storage organ – such as a rhizome, swollen root or tuber – and, as the new growth emerges, some of it can be used to take basal cuttings.
The principle of a basal cutting is to slice off some (but definitely not all!) of these new shoots at the very base and use the energetic, young material as cuttings.
Simply strip off the lower leaves, leaving two-four remaining leaves, and insert the shoots (usually around 3cm long) into a light compost mix.
A grit covering may be beneficial, as it helps prevent contact between the surface of the compost and leaves, which can be an entry point for diseases.
It may be the case that a shoot comes with some root as a token gesture – helpful for a fast start. Typically plants such as toad lilies (Tricyrtis formosana), iceberg sedums, tradescantias and even lupins offer good material for basal cuttings.
As well as basal cuttings, root cuttings can be used to bulk up a herbaceous border.
The range of plants which enable root cuttings is somewhat narrower, but it is an ideal way to propagate Japanese anemones, hostas and oriental poppies. Woody plants such as rhus and lilac can be propagated using root cuttings.
Choosing some of the broader roots, ideally those almost the thickness of a pencil or slightly broader, slice them into sections around 6cm long.
These cuttings can be laid horizontally in a pot of compost and covered with a light layer of sieved compost or grit, or the cuttings can be inserted the right way up so that the top of the cutting is level with the surface of the compost. It can often be difficult to determine a correct way round, so placing roots horizontally is usually the safer option.
Root cuttings are best taken when the plant is dormant, so now is very late in the season to be taking root cuttings, but root cuttings should start shooting quickly now.
As with any cutting, or propagation more broadly, it is essential to leave the parent plant in good condition. When taking basal cuttings, remember that the plant has only stored a finite amount of energy, so plenty of shoots should be left remaining. Equally, any plant selected for root cuttings, must have a healthy root stock and crucially do not use the main root, or tap root, for cuttings.
It is incredibly rewarding to watch your handiwork grow and taking cuttings is somewhat addictive. So why not create more plants and breathe new life into the garden around Easter?
PS – If you’re itching for some more plants to have a try at cuttings, or you have a gardening question, Manea School of Gardening is open for plant sales every Saturday, 10am-4pm.