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Now that summer is drawing to a conclusion, the flower garden at Gravetye Manor is beginning to reach its colourful maturity. Late flowering perennials and masses of annuals make up much of the display, but some of the star performers this year have been the salvias. Since starting at Gravetye, I’ve slowly been building up a collection of New World salvias -species native to Central and South America-as I’ve always appreciated their strong colours and distinct, interesting forms.

These plants are easily propagated from cuttings taken about now; over the years, I’ve grown to depend on them as a strong element, to lift a mixed border throughout the last half of the season. The following plants are just a handful of the most garden worthy salvias I recommend. Indigo Spires is a real cracker, 4ft-tall with 18in-long spikes of small indigo flowers arranged along purple stems. It has a usefully long flowering season, from early July until the first hard frost, and is presently looking good here growing next to the orange Dahlia David Howard, with Verbena bonariensis mixed through.

Salvia leucantha has downy, near-white stems and narrow green foliage, grey-white on the undersides. The selection known as Purple Velvet is the one to go for, being a good foliage plant in its own right, but also producing long spikes of fluffy, purple flowers-a brilliant front of border plant. Salva confertiflora is probably one of the most striking of the tall salvias, achieving a height of 6ft or more when conditions suit it. Each plant has masses of slender flower spikes bearing small, orangey-red flowers held close to velvety, dark brick-red calyces and stems. Its handsome dark-green foliage enhances these rich colours and, used as a strong vertical accent in the border, it combines well with the white, dome-shaped flowers of Ammi visnaga, both of these species being deeply fashionable plants at the moment.

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These salvias always seem to perform best in their second year, when they grow bigger and flower earlier and they’ll become quite shrubby over time. As they aren’t completely hardy, it’s best to lift the plants after the first frosts and overwinter them in a cool greenhouse. However, to ensure a succession of young plants, we always take semi-ripe cuttings at this time of year. These new plants will flower in their first year, when planted out in the spring. When harvesting cutting material, it’s important to select a strong mother plant, with no sign of drought or disease in order to give the best chance of success.

Strong upright stems of this year’s growth are selected, which ideally aren’t flowering, but if they are, the flowers can be removed when the cutting is prepared. We make the material ready immediately after harvesting, while it’s still fresh and healthy, making 3in-5in cuttings with a clean cut below the leaf node and removing all the leaves except the top pair.

If the remaining leaves are big, they can be trimmed down, to reduce moisture loss, and then I cram as many as will fit into a pot of 50:50 multipurpose compost and perlite mixture, kept in a plastic propagator in the greenhouse. I prefer to use a very sharp knife for the cuttings as blunt secateurs can crush and bruise the stem. Rooting hormone isn’t always necessary for success, but it certainly doesn’t do any harm. Countless other beautiful plants can be propagated in this way, and after many years of gardening, I never cease to be amazed to see a piece of stem I’ve cut from a plant develop its own roots and grow. There are many exceptions and variations to the propagation method I’ve described, so when propagating a new plant, I often like to confer with the RHS book, Propagating Plants, which we always have to hand in our potting shed.

There are lots of really good nurseries supplying salvias, although Dysons, in Kent (www. greatcompgarden.co.uk; 01732 885094), probably has one of the best collections. But as they’re so easy to propagate, one of the nicest ways to source plants is to befriend someone with a good salvia collection. At this time of year, I’m especially attentive to my salvia-growing friends, always visiting them with a gift bottle of wine-and a plastic bag tucked in my pocket for transporting the cuttings I hope to be given in exchange!

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