By Susan Rosenthal
Having covered the first two major salvia groups, the small leaf (woody stemmed) and deciduous perennial salvias, this month's plants of the month are in the third and final group - the rosette- and clump-forming salvias.
Rosette-forming species include S. argenta, S lyrata, S. pratensis, S. sclarea and many others. Clump-forming species include S. nemorosa, S. sylvestris and superba --the so-called meadow or woodland sages. These three in particular are closely related, with sylvestris probably a hybrid of nemorosa, and superba a hybrid of sylvestris; exact parentage is still debated, and it's not uncommon to find the same plant with a different species name.
Although there are relatively few clump-forming species, these are among the most widely grown salvias with familiar names like East Friesland, Blue Queen, Rose Queen, Blue Hill, Snow Hill, May Night, Blue Marvel, Marcus, Caradonna and many more. Several new cultivars are introduced every year.
The salvias in this group have flower stalks emerging from a whorl or mound of leaves close to the ground. Rosette and clump formers are sometimes considered as one, but they're slightly different. Rosette formers have a circle of leaves surrounding a central point, from which one or more flower stems emerge. There will usually be one rosette their first year. Additional rosettes may form, but these plants tend to be short-lived and need to be replaced every few years. A few even behave like biennials; Salvia argenta is a good example. Some species will spread by self-seeding.
Clump formers send up multiple flower stalks and more readily develop new whorls nearby, eventually forming a large clump. These can be divided in late winter/early spring. The clump formers are much longer-lived plants. Most salvias in this group are in the 18- to 24-inch range, useful near the front of a border or in a mass planting. Flowers are mostly in the blue-violet-purple hues (with a few pink, white and yellow varieties) and open over a long period of time.
After the first flush of blooms has faded, deadhead by cutting stems back to a lower developing bud. When these second blooms are spent, usually mid-summer, cut stems down to the ground. With our long-growing season, new flower stalks will emerge for a good fall bloom.
Plant in full sun (maybe a little afternoon shade), with average water and well-drained soil. Some are more drought tolerant than others. Root rot can be a problem if too wet, so allow soil to dry between waterings. In late winter, cut all stems back to the ground and remove any dead or tired looking foliage, especially underneath where disease often starts. Top dress with compost and avoid high nitrogen fertilizers.
Watch for snails and slugs when new growth emerges in the spring. As usual, pollinators love them. Native to Europe and Western Asia, these salvias are extremely cold hardy, as long as the soil is not too wet. More important in our area is their heat tolerance. May Night does exceptionally well here. Little Night, Blue Hill and Blue-by-You (a hybrid of May Night and an AAS selection) have also done well. Snow Hill has white flowers and blooms almost continuously all summer. Caradonna, with magenta tinged purple blooms, is also popular. Newer introductions, bred for color and more continuous bloom are worth trying to see which perform well over a long hot summer.