Getting more from your garden!
By ‘getting more’ I mean multiplying up your favourite plants the cheap and easy way — by taking cuttings. Although September is thought to be late for taking cuttings, it is in fact my chosen moment. The busy spring and summer seasons of the gardening year are behind us, but light levels and warmth are still adequate to persuade the many half-hardies currently doing colourful duty in mixed borders and pots, to root in double quick time. By ‘half-hardies’ I mean the more tender perennials such as the larger Verbenas, Venidio-arctotis, Diascias, Salvias, some Osteospermum, and many of the foliage plants that are downright tender, including Iresine, Helchrysum petiolatum and Plectranthus argentatus. Interestingly I also routinely take Penstemon cuttings at this time of year, although they are hardy in the ground, I often treat them as annuals. In my garden, they flower their socks off in their first year for many weeks longer than older stock can ever manage.
I think it was the late, great gardener Christopher Lloyd who said that the process of taking cuttings is a ‘race between rotting and rooting’. Fortunately, with a little care, plants are much more willing to do the latter than the former!
Soft cuttings are taken from the ends of non-flowering stems, about three inches is what you need, and these chosen shoots should be strong, healthy and typical of the parent plant. While gathering cuttings from the garden, pop them in a polythene bag to prevent them wilting before you finish the job. I always trim my cuttings on a clean board, with a new scalpel blade that I sterilise between each batch. Working quickly, carefully trim off the lower leaves flush with the stem, and if you have a large number to do, mist them lightly during the process to prevent loss of moisture.
When all of a batch are trimmed and ready, I dip the cut ends in hormone rooting gel. Most cuttings will root perfectly well without this extra help, but I find rooting gel does accelerate the process.
As I have so many cuttings to do for my work, and for my own garden — around a thousand at this time of year — I use a rather high-tech rooting medium to speed things along. I find that pre-formed cubes made of biodegradable material, complete with a hole in the top for the cutting, are invaluable; not only do I get almost 100% success rate with these, but the plants seem to root more strongly, and most do so within 21 days. However, these little rooting cubes are by no means essential, most gardeners have good results by inserting the cuttings in damp potting compost just inside the perimeter of a three or four inch pot.
Until roots have formed the cuttings need as much light as possible without ever being allowed to wilt or scorch. The way to do this if using a pot for the cuttings is to enclose them with a plastic bag held secure with a rubber band. A little refinement is to form a loop of wire, with the ends inserted in the pot, to hold the plastic bag clear of the leaves. I find that plastic in actual contact with the cuttings can lead to the dreaded rotting rather than rooting. During very hot bright days you may need to shade the pots to prevent overheating.
I am lucky enough to have a misting unit for my cuttings that works automatically with the aid of a ‘magic leaf’, a little gadget that senses when the cuttings are dry and initiates a burst of mist to keep them plump and perky until they root. You will usually know when rooting has taken place because the tip of the cuttings will start to grow away. If strongly rooted before the end of October, I pot them up individually in small pots and keep them just frost free, and on the dry side, in the greenhouse for the winter. A conservatory window cill would also be a fine location if you have only a few to overwinter. Those cuttings that have not rooted fully by the end of October, I simply leave undisturbed through the winter until the warming, lengthening days of spring encourage them into vigorous growth.
Although these tender perennials make great additions to borders — just as I use them in my garden to provide infill between the cannas, dahlias and ‘hardy exotics’ that form the backbone of my schemes — they are equally at home in more bijou gardens. They are happy in pots and containers where space is tight, and are joyously rewarding over a long summer season.
Groups from my own garden showing how tender perennials can lift mixed borders to another level, keeping them fresh and vibrant from late spring until the first frosts take them down.