Summer savings plan: how to take cuttings The type of shoot you take is important too. Choose sprigs that are blemish-free and look as though they are growing. When taking tip-cuttings or semi-ripe cuttings, if the plant is in growth then the chances of success soar. It's also best to choose material that isn't flowering. The reason is partly practical - flowers on cuttings always attract grey mould, potentially spreading rot to others. It's also partly physiological, as the way plants grow - upwards, downwards and when in flower - is dictated by an internal series of hormonal checks and balances. On a shoot topped with a flower, all the growth cells below it, including those with the ability to produce roots, are suppressed for the benefit of the bloom. On tender perennials, such as osteospermum and penstemon, finding non-flowering shoots is sometimes easier said than done, so you have to do the next best thing - take your cuttings and pinch off the flowers. This will trigger root growth, although you have to watch out as even de-budded cuttings often try to bloom again before they bother making roots. Collecting your cuttings The best way to gather cuttings is in two stages - I go around the garden snipping shoots with sharp secateurs and placing them, with a label and a drop of water (to keep them humid), into plastic freezer bags. Then, in the cool of the potting shed, I prepare my pots with cuttings compost. I use a 60/40 blend of multipurpose compost and sharp horticultural grit (to keep the mix open so that excess moisture drains) and pile it loosely into 4in (12cm) pots. When it comes to the type of multipurpose to use, peat-based composts are the most reliable - even bags that have been sitting under the potting bench all summer are still sterile. Peat-free, on the other hand, has to be fresh: over time the blend of bark and green-waste decomposes. Although harmless to plants, this can affect cuttings. An old boy I used to work with once told me that as part of his training he was told to carry three things: a penny to tip the boss, string to hold up his trousers and a sharp knife. The first two I've just about managed to live without, but a sharp knife is an essential - especially so for cuttings. Use a blunt blade and you'll leave tears and ragged edges that invite rots and see off your cuttings. When it comes to knives you get what you pay for; the best are made by Tina (grafting/general purpose knife, £52.49; qualitygardentools.com). The carbon steel blades are self-sharpening (why not put one on your Christmas list?). Some gardeners dib their cuttings into the compost: that is, they make a hole with a dibber to drop them in, but I prefer to push. Pushing ensures good contact with the compost and the slight wounding caused as the cutting scrapes through the grit triggers the development of repair (parenchyma) cells that divide and form new roots. Once done, water the pots with a rose. Put those with glossy leaves, such as penstemon and fuchsia, into the humidity of a propagator. If you don't have a propagator, make a mini-greenhouse with a clear plastic bag held over but not touching the leaves. If your bag flops, use sticks as tent poles to keep it up. Cuttings with waxy leaves, such as sedums and euphorbia, or downy foliage, such as pelargonium, plectranthus and many salvia, rot in close conditions. These I put under the greenhouse bench or inside a shaded cold frame to root. Tips To check that your knife is sufficiently sharp put up your thumb and place the blade carefully onto your thumb nail. If it slides, the blade could do with sharpening but if it grips then you're ready to go. Rooting powder is a sherbet-like dust containing hormones that encourage rooting and a fungicide that fights rots. Most cuttings root without it but it's worth using on plants that have proved tricky in the past. 10 easy strikers Salvia Argyranthemum Verbena Heliotrope Penstemon Pelargonium Osteospermum Fuchsia Plectranthus Coleus For a step-by-step picture guide, see How to take cuttings: a step-by-step guide