SpadeRunner

Salvia involucrata/wagneriana, a big showy subtropical sage

For sheer size and winter colour, Salvia involucrata/wagneriana varieties are outstanding in our subtropical garden.

This is the original sage in our collection. When we first moved into Hill House there was a well established patch growing at one of the entrance gates. It’s well away from the current house but nicely placed on the driveway to announce the house paddock with its big pink flowers from autumn to spring.

Naming

The cumbersome name I am using for this Salvia reflects my uncertainty about it’s identity. My searches to find a plant that resembled it led me to think it was Salvia wagneriana, going from labelled photos. However Sue Templeton at Unlimited Perennials suggested that it might actually be Salvia involucrata. Now that I have both species from her collection I can see that wagneriana has a different leaf, and my original plant is like her involucrata. It’s not quite the same though, so until my newly acquired plants have established for a year or so and shown their full character (and the new wagneriana has flowered), I’m provisionally sticking with the involucrata/wagneriana moniker. The closest photo I have seen to my plant was named a wagneriana/involucrata cross.

Cultivation

salvia wagneriana pruned

The Salvia wagneriana clump cut down to ground level.

This is a big salvia. It grows as canes which can be longer than 4 metres and arch with age to touch back to the ground. The canes grow from crowns, and the clump spreads moderately by suckering, seeds, or layering. Our clump covers a big area, maybe 5 x 10 metres, and sits in the afternoon shade of trees and some tree-sized bamboo.

The original clump was part of an overgrown garden, neglected for years

and partly invaded by lantana, so my first job was to get in, cut it back to the ground, and clear it out.

I guessed that winter, after the main flowering, would be a good time to cut it back. Fortunately the climate here is right for that sort of treatment, but I gather that a winter prune in colder climates could easily kill the plant (although it might not overwinter in cold climates at all). As you can see from the picture, I took it down to gr

salvia wagneriana

Salvia involucrata/wagneriana flowering in autumn

ound level and waited for it to re-shoot.

It responded vigorously, and by April was back to flowering, on the new canes. Another reason to cut back in Winter here is that we usually get a dry spell sometime between August and October. The new shoots start in August, so cutting back the old canes possibly reserves moisture for them to make a strong start.

Salvia involucrata/wagneriana is such a robust plant here that it really belongs at the back of a garden, or even as a broad hedge. It forms a bank several metres high, and es
sentially impenetrable, but does look good year round.

Propagation

dam wall 170517

The dam bank in May, covering well and starting to flower

dam wall 170303

The dam bank in March, after planting out the involucrata/wagneriana cuttings

Salvia involucrata/wagneriana grows very easily from cuttings.
Anything from the top 20 cm or so of a cane seems to grow, and I have rooted them in water or sand without cutting hormone treatment. It would also grow from sticks broken off and pushed into the ground if the ground stayed moist. We planted some just-rooted cuttings roughly in a spot freshly cleared of overgrowth, gave them one watering and then watched as spring turned very dry and hot, but the cuttings just went dormant and sprouted again after rain, so they get the tick for hardiness.

The ease of propagation let me grow 20 or so to a good size to plant across the top of our dam wall. We had cleared this of a very heavy lantana infestation and needed something to colonise the bank in replacement. The involucrata/wagneriana has done the job well. As one side of the planting gets pretty much full sun I expected that this shade lover would suffer a bit, but it has grown well right across the planting and is looking nice as winter begins.

My plants also set seed, but I haven’t tried to germinate them yet.

More on identification: wagneriana or involucrata?

As I became more interested in salvias and looked through the catalogues of species and cultivars, I began to have doubts about my initial casual identification of the plant as S. wagneriana, as S. involucrata seems very similar. Both species have flower spikes that terminate the canes, and begin as ‘buds’ inclosed in involucre bracts (petal-like leaves). The flower spikes then continue to grow, with progressively smaller involucres, until they leave the involucres behind. Without finding a proper botanical key, the information on the internet is a little vague and conflicted, but what I can gather is that wagneriana has large leaves with inconspicuous hairs and prominent veins on the underside, and it flowers in autumn and winter, while involucrata is smaller of stature and leaf, with downy leaves and is generally summer flowering. The ‘beetroot red’ flowers are also often used in descriptions of wagneriana, although flower colour is highly variable within species. To complicate things, I saw on an English nursery website a plant called ‘wagneriana x involucrata’ that looks very much like mine.

A final way of distinguishing some salvias is by scent, and my original type has a strong and distinctive scent, which I find pleasant.

I hope to get back with a more definitive post on the characteristics of these species.