Every year, the National Garden Bureau, a non-profit organization promoting the pleasures of home gardening, selects one annual, one bulb, one edible plant and one perennial to celebrate. It’s a great way to discover a new plant or to learn a bit more about a plant you may already be growing.
Let’s look at the perennial chosen for 2019, the perennial salvia.
Salvias are in the mint family (Lamiaceae) and are thus cousins to landscape favorites such as Nepeta(catmint) and Monarda(bee balm). Indeed, many salvia species reveal their family background through their square stems and the minty fragrance contained in their leaves.
There are more than one thousand species of salvia, making it by far the largest genus in the Lamiaceae. The genus includes annuals, perennials and shrubs, both tropical and hardy, coming from climates as diverse as deserts, tropical forests and urban landscapes.
However, most salvias are not hardy in colder temperate climates. This article focuses on the hardy types.
What’s in a Name?
The name Salvia is derived from the Latin salvare, meaning to heal or to save, as some species were used as healing plants. It evolved into the word “sage” over the centuries. However, this moniker is generally only used to refer to culinary and medicinal herbs such as the common sage or garden sage (Salvia officinalis), the one used to flavor our foods.
For the ornamental salvias we find in our flower beds, gardeners have mostly turned instead to the botanical name Salvia, so you can expect to hear “salvia” used for pretty much every ornamental salvia, be it annual or perennial.
Perennial Salvia History
English botanist George Bentham did the first extensive documentation of the genus Salvia in 1836.
One fascinating characteristic of salvia flowers is that they contain a trigger mechanism that deposits pollen on the back side of visiting bees. This pollen then becomes transferred to female salvia flowers that share the same receptive flower parts, encouraging pollination among the same or similar species.
The beautiful perennial salvias we find in our modern gardens originate from plants found throughout temperate regions of Eurasia.
The original hardy garden salvia is S. nemorosa (nemorosa is Latin for ‘of the woods’) and used to be called woodland sage, although you’d more likely hear it called “perennial salvia” today. It turns out that S. nemorosa readily crosses with meadow sage (S. pratensis), giving the hybrid species S. × sylvestris. And that hybrid sage was further crossed with southern meadow sage (S. amplexicaulis), giving yet another hybrid species, S. × superbum. And other species may also have been used in crosses. The result of all this hybridization is a confusing nomenclatural mess: no one actually seems sure which perennial salvias are pure S. nemorosa or to which of of the various hybrid species they belong.
That’s why, although the entire group of similar hardy salvias is sometimes referred to as Salvia nemorosa by growers, I prefer the more inclusive term “perennial salvia” and that’s the name I’ll use in this article.
Note that interspecies crosses often result in sterility and indeed, many perennial salvias are either sterile or produce few viable seeds.
Much of the early work in hardy salvia breeding was done by German plantsman Ernst Pagels who is credited with breeding varieties ‘Blauhügel’ (Blue Hill) and ‘Schneehügel’ (Snow Hill) shortly after the Second World War. Both of these are still in commercial cultivation and are found in garden centers during spring and summer. Today, there are several hundred varieties of perennial salvias from which to choose.
Likely the most common and well-known cultivar, also a product of Pagel’s innovative German breeding, is ‘Mainacht’ (MayNight), introduced in 1956. Named Perennial Plant of the Year by the Perennial Plant Association in 1997, ‘Mainacht’ remains a favorite among landscapers for its abundance of indigo-blue flowers and pest and disease resistance.
Other standards include the upright, dark-stemmed variety ‘Caradonna’ and the dark purple cultivar ‘Ostfriesland’ (East Friesland).
These tried-and-true classics are slowly being replaced with exciting new varieties from flower breeders in the United States and Europe. Award-winning cultivars such as ‘Blue Marvel’ and ‘Rose Marvel’ present extra-large flowers and provide a much longer flowering window. Newcomer ‘April Night’ is earlier to flower, as the name suggests, and is especially popular with southern gardeners. ‘New Dimension’, ‘Bordeau’, ‘Salute’ and ‘Swifty’ are all new introductions that are bred for improved garden performance.
Also, breeders have been backcrossing the various hybrid salvias to S. pratensis, with its larger “parrot beak” flowers and a more open and airier flower presentation, giving such attractive varieties as the Fashionista™ series (‘Pretty in Pink’, ‘Midnight Model’, ‘Moulin Rouge’, etc.) and Salvia ‘Blue by You’.
Care and Cultivation
Perennial salvias like S. nemorosa and its hybrids are considered to be essentially carefree and easy to manage in the garden. They can be in place for years without a need for dividing. They are also a favorite of pollinators like bees and hummingbirds.
As a member of the mint family, their aromatic leaves are not on the preferred forage list of deer and rabbits and considered to be a great garden addition where these creatures are a nuisance.
Be sure to plant in a location where they will receive at least one-half day of direct sunlight, as this will provide an environment that encourages the highest degree of flowering. They are generally considered hardy from hardiness zones 4 to 8 and may be worth trying in protected spots in zone 3.
Perennials salvias prefer soils rich in organic matter, so it may be necessary to add compost, peat moss or topsoil to your sandy or heavy clay soil before planting.
Once established in the garden, salvias are quite drought tolerant, only requiring watering when landscape shrubs such as Hydrangeashow signs of wilting.
To maintain healthy green growth, plan on fertilizing your salvias when they emerge from dormancy in the spring and once again in early summer. Applying any all-purpose fertilizer according to label directions will do the trick.
Sometimes plant descriptions read as though perennial salvias bloom all summer, but in fact, they initially bloom for a month or so, then stop. To encourage them to rebloom, cut the plants back aggressively to about one third their original size once the first flush of flowers has finished and the flower stems have turned brown. Doing this causes the Salvia plants to push up new shoots from the root system, and you will be rewarded with a new flush of flowers in four to six weeks. You can repeat this a second time for fall bloom in climates profiting from a long growing season.
Multiply your salvias by stem cuttings or division. Some varieties are available from seed.
Perennials salvias are delightful additions to any temperate climate garden, and it is certainly fitting that the National Garden Bureau has deemed 2019 to be the Year of the Perennial Salvia!
The following companies collaborated in the Year of program and offer perennial salvias for sale by mail order.