The Genus Salvia contains a staggering 900 species – some of which are the most highly ornamental in the entire plant kingdom. At Dyson’s Nurseries our main interest lies in the New World species and cultivars ie. those from Mexico, Central and South America and the southernmost states of the USA. These plants are notable for their often considerable flowering period and a diversity and intensity of flower colour seldom equaled in other genera. Some are hardy in the southern counties of Britain whilst others are tender and require glasshouse protection over winter, but all are immensely garden worthy and merit much wider cultivation.
Our advice regarding cultivation and hardiness of any particular plant is based purely on our experience of growing these plants here in North West Kent over the past 20 years on well-drained sandy soil with minimum winter temperatures of approximately -10 degrees celcius.
There are, broadly speaking, four distinct categories of Salvias offered in our catalogue; these categories are determined largely by overwintering requirements. However, two requirements that are common to most of these plants are a well-drained soil or compost and as much sun as possible. Unless protection is available planting is usually best carried out between May and August as this gives the plants a chance to build up a good root system and ripen their wood before the onset of winter.
These are generally hardy, obliging plants producing vast quantities of flowers over an extremely long season, provided their main requirements of full sun and good drainage are met. Tidy minded gardeners can remove the spent inflorescences during the growing season although this is by no means essential. Autumn or winter pruning should be avoided as this can encourage new growth which is susceptible to frost. We prune our plants in spring (mid to late April), this involves removing any dead stems back to where new growth is emerging. After a hard or very wet winter plants may not have any visible signs of re-growth above ground but will often regenerate from below ground. If there has been no re-growth by mid-June then the plant is probably dead.
Hardy Herbaceous Salvias
These are generally regarded to be hardy throughout much of the UK. They are generally late spring and early summer flowering plants, however re-blooming can be encouraged by cutting back to just above ground level immediately after their main flowering period. Cut back again in either autumn or early spring.
Half Hardy Herbaceous Salvias
These require a more sheltered position but are otherwise reasonably easy to overwinter. In very cold areas S. patens can be mulched during the winter to protect the tubers from frost or the plants may be cut back, lifted and overwintered in a cool, frost-free place pretty much as for Dahlia tubers.
Half Hardy / Tender Shrubby & Woody based Salvia
Apart from those fortunate enough to garden in mild coastal or sheltered London gardens, the rest of us have to give these plants a ride in a wheelbarrow to more congenial winter quarters. Indeed several are triggered into flowering by the shortening day lengths of autumn and winter thus making them excellent subjects for the conservatory, often blooming well into the spring. The pruning of this group is generally a matter of shaping and the removal of spent inflorescences.
With so many new species being discovered, we are continually evaluating new plants here in Kent to determine their hardiness and cultivation requirements. However some plants are so new to us we are simple not able to accurately assess their hardiness yet.