Propagation by cuttings
Want free plants? Then get out your secateurs and take cuttings from shrubs, climbers and perennials.
Taking cuttings is a great way to increase your stock of your favourite plants, but when you take your cuttings will determine how you need to take them. There are three main methods: softwood, semi-ripe and hardwood.
WHEN TO TAKE CUTTINGS
Softwood cuttings are taken in late spring to early summer from the soft green tips of plants. They give the quickest results but they are also the most likely to fail. This form of propagation suits many of the herbaceous perennials and shrubs. Some softwood cuttings, like those of begonia and pelargonium, can root in a glass of water, and can then be potted up. Cut 7.5-10cm long stems from the tips of plants. Remove the lower leaves but keep the upper, then pot up into seed-raising mix.
Take semi-ripe cuttings in late summer to early autumn when growth has slowed and the stems are firmer. This method suits evergreens, climbers, shrubs and conifers. Take stems from the top or outer growth. They should be firm at the base but fairly soft at the top. Cut just under a leaf node, where growth hormones congregate.
Hardwood cuttings are taken in late autumn to winter, from mature woody stems. This method best suits deciduous shrubs and trees. Choose healthy stems 15-20cm long and about pencil thickness. It's important to maintain moisture levels (not too wet, not too dry) until the cuttings form roots to take up moisture. Regular misting will keep cuttings turgid until roots form.
DIVIDING PERENNIAL PLANTS
Plants, like children, benefit from being separated when they start to misbehave. The individual plantlets in a swathe of phlox or Michaelmas daisies, for example, suffer from botanical claustrophobia. After a few years, their congested centres go bald, they don't grow as lush and their flowers are sparse. This is because nutrients in their patch of soil are depleted, and since perennials spread by producing underground stolons or rhizomes, they naturally move out in their quest for new pastures.
To divide a patch, chop all around with a sharp spade. Then try to get under the roots and lever out the whole plant. Split clumps – either thrust two forks, placed back to back, into the clump and push the handles together and the parting prongs will tear the clump naturally, or use a sharp spade. You may need to take an axe to old-timers. Small perennials can be split with a knife or old secateurs. Don't split clumps into hundreds of tiny pieces; you'll lose many of your offsets. Trim unwieldy roots, then replant divisions in fresh soil. Discard or pot up the bulk of the original plant. Three to five clumps are plenty to replace one large perennial.
HYBRID OR HEIRLOOM?
Saving your own seed is easy, but the type of plant you collect seed from will determine the seed's viability. Openpollinated and heirloom plants come true to type (they produce seedlings just like their parent plant); hybrids don't.
That's because hybrids are created by cross-breeding two compatible plants so that they produce the best features of their parents. However, seed that is produced by hybrid plants is genetically unstable, and likely to revert back to one of its parent's traits. So it's best to buy new seeds of hybrid plants each year for sowing. Open-pollinated and heirloom plants, on the other hand, can be collected and sown, and remain true to type year after year.
Some plants are sterile, so either won't produce seed or the seed is not viable. Certain varieties of sunflowers are naturally pollen-less, or male sterile (they possess only female characteristics). They are bred to have no pollen so that they make better cut flowers (they don't shed yellow dust and are not allergenic). Pollen-less sunflowers still make seeds just like any sunflowers if there are others with pollen nearby, though the seeds will yield flowers with different traits, if sown.
Mophead hydrangeas produce sterile flowerheads, so taking cuttings is the way to propagate these plants.