A few years back I was checking out a stand of ornamental grasses at Chelsea Flower Show and was curious about the range of unfamiliar (and mostly evergreen) grasses on display. I liked them well enough – particularly when grown as well as you’d expect anything on display at Chelsea to be – but couldn’t help but wonder about the management of them, long term, which is generally much trickier than that required by deciduous grasses.
Wondering where to start in conversation with the exhibitor, I asked him which of these grasses he considered to be the most underused and underrated of them all. Without
hesitation, he stated that it was Poa labillardieri. I was flabbergasted. And then a bit disappointed.
We’ve all seen Poa lab (as we all call it, in order to avoid the embarrassment of forgetting, and therefore mispronouncing, the order of ‘i’s and ‘e’s in those last few syllables) looking appalling along freeways in Australia – the very essence of the deeply flawed but still widespread belief that Australian native plants don’t require maintenance. After three or more years a plant of Poa lab without any maintenance is at least 70% dead matter (‘straw’ as it’s known amongst its industry acquaintances), and 28% half-dead matter. At that point in life it tends (in garden settings, or parks, where it’ll get trampled or squashed) to become brittle, so great chunks of it fold over and eventually shed, winding up looking like the patchy wig on the Gerry Gee doll with which my much older brother terrorised my childhood. Hence my flabbergastedness.
That turned to disappointment as the inevitable internal question started to formulate “If Poa lab is the best of them, how bad must the others be?”
Given all that, I did ask the guy pushing the plants how Poa lab is best treated in Britain, in order that it should look its best in perpetuity. He told me that it should be handled like most of the other grasses, and given a hefty hair cut – virtually to the ground – in spring. Frankly, I don’t see how this could work. Deciduous grasses can be cut back to stumps anytime after their foliage has died in autumn through until the new growth emerges in spring, as the plant has clearly finished with it and retracted a high proportion of the nutrients it needs for regrowth. The same isn’t true of evergreen grasses. They’re not necessarily equipped to fully replace themselves every year. You certainly can’t treat Poa lab like that here in Australia. Nevertheless, I really wanted to believe this guy, and to that end wondered if perhaps the colder/more emphatic winter in Britain forces a different growth pattern onto it, allowing for this treatment.
In our climate, my understanding is that Poa lab is largely a winter growing grass, or at least a cool season grass. Some gardeners in our local Council have told me that they’ve had great success with cutting it hard in Autumn. I should have asked whether they do this annually, but didn’t.
This pic above shows a friend’s garden where we used Poa lab extensively, about three years ago, and in a really prominent place in the front of their house. These were cut back last Autumn for the first time, and are recovering, but not rapidly. With that pace of recovery, you certainly wouldn’t want to cut them every year.
The question remains as to whether they’d have recovered faster if they’d been cut back every year from when they were young plants. These same friends had cut back much younger plants elsewhere in their garden at the same time, and these had recovered much faster but were not yet in full flower. They were, however, planted in much better soil, and this appears to make a great difference to the rapidity and extent of their recovery.
These sorts of management questions are poorly understood with most of the evergreen grasses. We’ve all seen patches of the lovely (when young ) Festuca glauca that has been shaved back hard in an attempt to restore its youthful freshness, only to result in patchy tufts that put me in mind of a 70’s comb-over. Likewise the carexes (which aren’t actually grasses, I know, but are used in exactly the same way and present the same problems). Why don’t those selling such plants provide us with guidelines/principles about how to keep them looking fresh in perpetuity – or at least for a reasonable number of years? In a garden setting (as compared to one in which these plants are used en masse), I don’t bother trying to manage the older plants, but simply replace them every three years or so with inevitable self-sown progeny.
There’s other considerations as well that I’m reluctant to start on (given that they might take me a few thousand words to articulate) that deal with the idea of inherent modesty in a straw-filled plant like Poa lab and it’s consequent usefulness as a matrix/background plant for other modest, low-showiness-rated Australian native plants. The cleaner, more highly groomed presentation of the deciduous grasses on the other hand, might simply be a better match for the showier exotic perennials. Maybe we’ll deal with that huge question some other time.
Meanwhile, while the questions remain, in my own garden I’ll be sticking largely with the much-easier-to-manage deciduous grasses. But I can’t shake the conviction that I’m missing out on something..