Snow tussock and toetoe: choosing between the big native grasses
Quick answer: Toetoe (Austroderia richardii) is the big one. Foliage to 2m, cream plumes to 3m in December, fast, and it copes with wet ground or dry. Chionochloa rigida is the small dry-country snow tussock at about 1m by 1m. Chionochloa rubra sits between at 1 to 1.6m and colours up copper in the cold. Chionochloa conspicua is the broad-leaved forest-margin one, around 2m.
Late April, driving the Maniototo road with the sun almost on the hills. A whole basin of tussock going gold and copper, every head lit from behind, the wind moving through it in long slow waves like a swell coming in. You slow down. Everybody slows down.
Then you get home to a flat quarter acre in town, or a shelterbelt gap on a paddock edge, and you try to order some of that. And the trade list gives you four names.
Chionochloa rigida. Chionochloa conspicua. Chionochloa rubra. Austroderia richardii. In the head they are all one plant. On a real site they are four, and two of them will make you look silly if you put them in the wrong spot.
What are we choosing between here?
Two genera, doing two different jobs.
Chionochloa is the snow tussock genus. Grasses of open country, above the treeline, on cliffs and bogs and the big inland basins. They want an open aspect and air moving through them. Put one in a still, sheltered pocket and it sulks.
Austroderia is toetoe. Different plant, bigger, coarser, and a riverbed and streambank specialist. Austroderia richardii is the South Island one, from the coast up into subalpine country, and it turns up along stream banks, river beds and lake margins.
Drainage and exposure separate them. Get those two right and any of the four will grow; get them wrong and you replace plants.
How big does each one get?
Biggest to smallest, and the gap is wider than the trade list suggests.
Austroderia richardii (toetoe): foliage to about 2m by 2m, with creamy white flower heads standing 2 to 3m from December into January. Rapid growth, 2m inside five years.
Chionochloa conspicua (hunangamoho): about 2m tall by 1m wide, wide leaves and the largest flower panicles in the genus. The one most often mistaken for toetoe.
Chionochloa rubra (red tussock): 1m to 1.6m. Some forms of the copper tussock subspecies sit at the shorter end of that.
Chionochloa rigida (narrow-leaved snow tussock): dense clumps of foliage at 60 to 90cm, about 1m by 1m all up, flowering stems to roughly 1.5m in summer.
That is a plant a bit over knee height at one end of the list and a plant taller than you are at the other. If you are a landscaper specifying off a plan, that difference decides whether the client can see over the bed. Buying for your own place, it decides whether you can still get the mower past in three years.
Which one takes wet ground?
Toetoe, without hesitation. Then rubra. Rigida is the one to keep out of it.
Austroderia richardii handles dry, moist and wet ground, and it does most of its work in revegetation and erosion control on riverbanks and drain edges. Southern Woods rate it for all three drainage bands and note it does well under pivot irrigation, so it is not going to mind a Southland winter's worth of standing damp.
Chionochloa rubra is the adaptable one. In the wild it gathers where the moisture does, on plains, valley floors and wetland margins, and in cultivation it takes exposure, dry ground and considerably damp ground. Lawrie Metcalf noted it colours up more strongly in the cold and in damp conditions, which is the whole reason the Mossburn and Te Anau flats look the way they do in July.
Chionochloa rigida is the opposite. Full sun and free drainage, and rich or wet soil brings crown rot. On a heavy flat paddock corner that stays soggy into November, it will not last.
The catch on rubra, and it is the one people get caught by: it does not cope with drought in its first year. Adaptable once it's away, thirsty while it establishes. Plant it in autumn and let the winter do the watering for you.
Which one handles the hardest, driest country?
Rigida, and that's what it is for.
Narrow-leaved snow tussock is the dominant tussock of the drier eastern country, up the Crown Range and across the Central Otago basins. It takes harder frost and drier soil than red tussock does. If you are planting at Ranfurly or Alexandra, where the ground bakes in February and the frosts go far deeper than anything the Southland coast produces, rigida is the specification.
It is also slow. These are long-lived, slow-growing plants, so a 2.5L plant is not going to be a photogenic tussock next autumn. Two to three seasons before it starts to look like the picture is a fair expectation on a dry site.
What do they look like in winter, and will they flower every year?
All four hold their leaves through winter. The flowering is the part nobody warns you about.
Evergreen is the easy half. Toetoe stays coarse green. Rigida holds its narrow blue-green to gold. Rubra is at its best in the cold, going through copper and red as the temperature drops, which is the opposite of most things in a July garden.
The flowering is less obliging. Chionochloa mast. That means heavy flowering in some years and very light flowering in the years between, with no set pattern to the spacing. The strongest explanation is that it starves out the insects that eat the seed. Whatever the mechanism, the effect on a garden is that a bed of snow tussock can put on a full show one summer and almost nothing the next, and nothing has gone wrong.
Austroderia does not do this to anything like the same degree, so if somebody is buying the plume specifically, toetoe is the more reliable purchase. If you are a landscaper selling a tussock bed on the strength of the flower heads, say this out loud before it gets planted.
How far apart should they go?
Far enough apart to still be individual plants, unless you want a solid mass.
For rigida, The Plant Company publish 80cm to merge into a cover, 90cm to 1m to merge partially, and 1.2m if each tussock is to stand as its own shape. That is a sensible working set of numbers and it scales up for the bigger species: a 2m toetoe planted at 80cm centres is a hedge you cannot walk through, not a planting.
For toetoe on a bank or a drain edge where the job is coverage and erosion control, 1.5m centres is the usual working figure and the clumps will meet. As specimens in a garden, give each one 2m and mean it.
The mistake is almost always the same one, and it is not spacing measured in centimetres. It is buying the number of plants that fills the bed now.
When is the wrong plant, and who should not buy toetoe?
Toetoe on a small site. It is the single most common mismatch in this group.
Two metres by two metres, plus flower heads over your head, plus rapid growth, plus leaf edges that will open your forearm if you push through it in a t-shirt. On a lifestyle block boundary or a river flat that is a plant doing a job. In a 3m courtyard bed it is a mistake that takes a mattock and a bad afternoon to correct.
The other three regularly go wrong in these ways:
Rigida in wet or fertile ground. Rot at the crown. Put it on the bank, not at the bottom of it.
Rubra planted in spring and forgotten. First summer drought while the roots are still shallow is what kills it.
Conspicua bought as a cheap toetoe substitute. It is a good plant in its own right and it sits at forest margins rather than out in open grassland, so it wants a different position than the other two Chionochloa here.
And all four of them are grasses. They get untidy, they hold dead leaf inside the clump, and somebody has to comb or cut that out every few years. If nobody on the property is going to do that, plant a shrub.
Common questions
Is toetoe the same as pampas?
No, and telling them apart matters because pampas is a pest plant. Toetoe is our native Austroderia. Pampas is Cortaderia selloana or Cortaderia jubata, from South America, and it seeds prolifically into cleared ground. The quickest field difference is the flower head: toetoe plumes are creamy and droop, pampas heads are denser, more upright and often pink to purplish. Leaf bases and the way the old leaf breaks are the reliable tells if you want to be sure.
Can you cut a tussock back hard?
Not the way you would cut a flax. These are clump grasses that do not reshoot readily from a hard chop, so hard cutting can leave you with a dead-looking lump for a long time. Comb the dead material out by hand with a glove on, or tidy the old flower stems and damaged foliage in late winter, and leave the crown alone.
Do they need feeding?
No, and rigida is worse for it. Rich soil pushes soft growth and invites rot. These plants come out of low-nutrient country and they are at their best on ground that does not spoil them.
Will stock eat them?
Snow tussock is grazed, which is a large part of why it has retreated from a lot of low-country farmland. If you are planting tussock on a paddock edge or in a riparian strip and you have stock, they need to be fenced out or guarded until they bulk up.
Which one do I plant if I want the roadside look?
Chionochloa rubra, planted in a drift and not in a line. That colour and that scale in low winter light is the thing you slowed down for.
Get the ground right first, then the species, then the numbers. That order fixes most of what goes wrong with these grasses, and it is the same order whether the site is a courtyard bed or 400m of drain edge.
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