Thursday, December 8, 2011

Kangaroo Grass

Themeda triandra

The distinctive heads of this unmistakable plant are highly visible around the district at the moment, as they begin to go through their summer colour-change. The leaves go from light green to red-brown and the pretty flowerheads ripen to a showy russet-colour.

This was once Australia’s most widespread grass, and it is one of the easiest native grasses to identify.

Deservedly our most popular ornamental grass for landscape gardening, it is also useful in floral arrangements. One of the staples of a good wildlife garden, it is very attractive to birds, which appreciate the feast of large seeds. A nutritious plant, it is popular with kangaroos and wallabies, and with introduced livestock, which have grazed it heavily since the time of European settlement. Unfortunately it is easily killed by overgrazing, so tends to vanish from pastures.
It has been used in native lawn mixes, but just as it doesn’t tolerate heavy grazing, it can be killed by being mown too frequently or too short. It grows as a tussock, rather than spreading as do the better-known introduced lawn grasses, so you would only use it for a “lawn” in an area where this might be rather roughly defined!

"Cultivated grassland" would be a better term, and it would be a pity not to let it go to seed each summer.

In pre-European times, kangaroo grass was managed with a regime of annual (winter) burning, which refreshed the plants ready for the new season. Burning is hardly practical in a garden, but a cut-back after the seeds have dropped, by hand or a high-set lawnmower, will result in more vigorous plants as well as natural regeneration. It is better if the grass cuttings are collected and removed, as this is not a plant that likes mulch.
Collecting seeds for propagation purposes can be a little tricky, as they must be very ripe - firm and hard rather than milky, and there is only a narrow window of seed-collecting time before they fall off the plants. A successful technique is to put a seed-trap under the plant to collect fallen seed, and empty it daily until enough has been collected. The seed then needs to be stored for nine months for “after-ripening” before being planted. It needs a cold period to help it germinate, so seed which is taken indoors should spend 4 weeks in the fridge, before being planted out. It is time to plant it once the daytime temperatures are over 25°.
We think of kangaroo grass as the quintessentially Australian grass, so it’s a bit of a surprise to discover that it is also native to South Africa. There they call it rooigrass - an Afrikaans word meaning “redgrass”. It is the only African species of Themeda, and it was given its botanical name there. "Themed” is an Arabic word referring to a depression where water lies after rain and dries up in summer - a clue as to how the grass likes to grow - plenty of water to get started, after which it will happily tolerate drought. It’s also frost hardy.


Tom said...

Thanks for that information Patricia - I have been searching for tips on propagating Kangaroo Grass. I find the look of native clumping grasses most attractive and want to "regrass" an area on my property in Chandler (Brisbane) with this and other native clumping grasses. I have enjoyed your other posts as well and will return!


Patricia Gardner said...

Nice to hear from you, Tom.
I'm delighted to hear you're regrassing your property with native grasses. I agree with you that they have great ornamental potential, not to mention being just what our native wildlife like.