Carol Klein on dividing the ‘toughies’ among your plants
This is the ideal time to start dividing lots of the ‘toughies’ among the plants in your garden
All of us enjoy making more plants, don’t we? And the most straightforward way of increasing almost every plant is to divide it into several pieces, thus creating new ones.
It’s unlikely to give you as many plants as growing from seed, but there’s none of the waiting and watching; it’s as instant as it can be and immensely gratifying. For very little effort you can create several new plants, put them into the ground and let them get on with it. Apart from growing from seed, it’s probably the oldest method of propagation.
There are two optimum times for dividing plants, and this is one of them. It’s a bad idea to divide in autumn any plant that flowers in the second half of the year. Very often these plants have put their all into flowering and, possibly, producing seed. By far the best idea is to leave such plants as asters and rudbeckias to recover, gather their strength during the winter and then dig them up, pull them apart and replant as the soil begins to warm. Perhaps with those particular ones it’s best waiting until April or so, but this is an ideal time
‘For very little effort you can create several new plants, put them into the ground and let them get on with it’
to divide lots of tough plants. I need some exercise and getting to grips with daylilies, astrantias and geraniums, such as G.
psilostemon, can be demanding enough to get you taking off your coat and rolling up your sleeves!
For such plants, the best method is to lift the whole clump, plunge two ‘backto-back’ forks deep into the centre and push the handles together, levering the clumps apart. This can be repeated until there are several healthy chunks to replant. At the same time, the woody, unproductive centres can be discarded.
Roots come in all shapes and sizes and the methods for dividing each sort of plant has to be appropriate. In the case of fibrous-rooted plants, such as primroses and epimediums and their ilk, pulling clumps apart is the most efficient method.
The best time to divide primulas is, as Gertrude Jekyll put it, ‘when their flowers are on the wane’. In late May or June, old clumps can be lifted and pulled into separate rosettes, each with its own roots. Those roots should be trimmed to about the length of your palm so when they’re replanted (with a suitable addition of home-made compost), they’re not folded or bent back. A little more force and the use of a sharp knife may be necessary when splitting epimediums, and it’s best carried out when they’re dormant.
Pulmonarias have thong-like roots and are best lifted when they’ve finished flowering and pulled into separate pieces, discarding the old woody crowns and roots. Solid crowns like hostas can be sliced with a sharp spade, either into quarters or by taking out slices as though the rootball was an enormous cake.
Sometimes plants practically divide themselves. You can almost hear herbaceous lobelia and helenium asking to be pulled apart! Grasses, too, are best divided in spring when they get growing as soil gradually begins to warm up.
Dividing herbaceous plants has much to recommend it. Simple and straightforward, it has few of the risks, problems and dramas that attend some methods of propagation.
Providing divisions are made at the right time and replanted sensibly, nothing much can go wrong. Us gardeners can immediately see and use the fruits of our labours. New plants are made instantly and should grow and flower in the same year from spring division, or in the next season if we divide them in autumn.