Tag Archives: Calamagrostis ‘Karl Foerster’

The grass report

I feel sufficiently confident to give an interim report on the grasses I have used in the new Court Garden although it will take another few years before I can give a definitive verdict. These are bigger growing grasses because we had the space and I wanted an immersive effect that wraps around when we walk through the area.

The site is the hottest area in our garden but, being lowered, it can also be frosty in winter. Cold air flows down to lower levels to settle. The ground is typical free-draining, Taranaki volcanic soils that do not become water-logged and never dry out entirely. We haven’t added any fertiliser and once planted, we never water. The area is mulched with wood chip.

Chionochloa rubra – commonly known as red tussock but this form is only brownish red in winter

Chionochloa rubra – NZ native so evergreen. It takes first prize for graceful form because it fountains out from a narrow base and that form makes it a real star in the winter garden. Its flowering is relatively insignificant but I don’t have to groom the plants to remove dead sections. We started with just one plant and I kept dividing it, which it does easily. I have never lost a plant. It needs space to be able to appreciate the graceful form and the best plants are now 120cm high with a spread up to 2 metres.

Chionochloa flavicans, sometimes sold as ‘miniature toetoe’ though it is a different family

Chionochloa flavicans – also a native, sometimes referred to as ‘miniature toetoe’, so evergreen. At its best in spring but holds its showy flowers right through until autumn. Rabbit fodder when young. Has the reputation of ‘whiffing off’ unpredictably and it certainly doesn’t appreciate being crowded by other plants. Again, we started with a single plant and kept dividing. I have overplanted it so will lift the lot shortly and split the plants, replanting fewer and at wider spacings. I am hoping that by dividing, it will stimulate more growth and delay any inclination to ‘whiff off’. Plants are now about 75cm high and up to 140cm wide.

Anemanthele lessoniana or NZ wind grass, sometimes gossamer grass (you can see the ethereal flowers in pink tones) in the borders before I moved it over to the Court Garden
Anemanthele after moving – it turns golden under stress and it was still hot weather when I moved these plants but I expect them to recover

Anemanthele lessoniana – another native – so evergreen – with a vase shaped habit of growth and more colour variation in the foliage. Lovely in bloom with a cloud of fine flower heads. I had this in the twin borders but the plants were getting too large so I have now moved them to the Court Garden. When stressed (and my plants have often been stressed as I have lifted and divided them to increase the number from the original three), it turns an attractive gold but I will need to groom the foliage to remove dead thatch when the plants make fresh growth. It has reached about 90cm high and up to 140cm wide.

The tall plumes are the austroderia – NZ toetoe and a better choice than Argentinian pampas

Austroderia fulvida – toetoe so another evergreen native.  Very large growing and too early for me to comment on its longer term performance. I bought three small plants through Trade Me and they have already reached 1.7m high and 2.4 metres wide.

Stipa gigantea I have referenced countless times. It, too, is evergreen in our conditions and I  give it the occasional groom (by hand or with a leaf rake) to remove dead foliage. Excluding the tall flower spikes, it is about 80cm high and 160 cm wide as it matures. It divides and increases easily so just start with a single plant but you do need a certain critical mass to have sufficient to share with the sparrows. We found the pesky birds stripped the blooms in the first season and the whole reason for growing this grass is for its showy, long-lived flower spikes so that was disappointing. This year we have had plenty to share with the birds. The foliage has a glaucous tint which is a contrast.

Calamagrostis ‘Karl Foerster’ to the left with the plumes still looking good after four months

Calamagrostis ‘Karl Foerster‘ – I have written about this before. It is such a strong grower, spreading at an alarming speed, that I reduced it down to just six plants which I am hoping I can keep in check by root pruning on an annual basis. By root pruning, I mean getting a very sharp spade and cutting back the size of the clump without digging it all out. That way, I can get the spreading fresh growth off it. This works because it makes its new growths on the outside of the clump. It is evergreen in our climate but the foliage looks pretty scruffy by the end of season. I am pretty sure I cut it back hard last winter so the spring growth was all fresh and lush. It is one of the first grasses to flower in spring and those lovely plumes hold all summer and into autumn. It is all about the plumes because the foliage and form are nothing remarkable.

That is what I think is ‘Overdam’ in the front right, Stipa gigantea behind

Calamagrostis ‘Overdam‘. At least, I think it is Overdam. It was given to me. It is strong growing too, but not as threatening as Karl. It has the same lovely plumes but the bonus of clean, variegated foliage which stays looking fresh through the season, somewhat like a lower growing variegated miscanthus, though it spreads sideways rather than up. It will likely need root pruning, too.

Miscanthus is a lovely grass from spring onwards but the glow of those white plumes in the low winter sun is nothing short of amazing

Miscanthus sinensis ‘Morning Light’. Look, we started with one plant in the garden years ago that just sat, grew annually and fell apart because it needed dividing. As soon as I started dividing it (done variously with a sharp spade, an old handsaw or a small axe), it responded by growing with huge enthusiasm. I overplanted badly and need to take out at least half of the plants but as it is all about the plumes in late autumn and early winter when they glow white in the low sun angles, I will wait. The plants are around 1.7 to 1.8 metres high with flower spikes on top of that so it is very tall. If it is divided often enough, it will stay together – falling apart from the middle is a sign it needs dividing. It is fully deciduous, fine leaved and variegated. Mark is sure that the old foliage has potential for thatching but he has yet to test this theory. This is the only grass that I have spotted seeding down so far but the seedlings are easy to pull out when small.

Miscanthus ‘Morning Light’ on the right, giant miscanthus on the left

Miscanthus whatever whatever – may be just a larger growing form of sinensis with a wider leaf but it should be called Miscanthus giganteus variegatus. The leaves are wider and with a most attractive, clean variegation but the vigour and size is daunting. We ended up digging out three massive plants because I couldn’t hold them together and, as they fell apart, they blocked the path entirely. This is a triffid of a grass. Gardening friend, Susan, suggested that maybe the way forward is to do the Chelsea chop on them – cut them back to ground after the first big flush. I think she is right and I will be cutting them back to ground level about mid November. The second flush of growth should be more compact and shorter. If I can’t keep them under control this way, they will have to go. The plants are too big for me to lift alone and I don’t want to commit to plants that need lifting and dividing annually.

Just too big – they grew even larger and floppier after I took this photo

Lomandra We had a named variety in the garden but I found a better option to replace it with. I rate lomandra as one of the world’s more boring plants and I suggest you leave lomandras to supermarket carparks and roading roundabouts. We have more interesting and attractive native grasses without having to resort to this utility Aussie in NZ gardens.   

Here endeth the interim grass report. Except to say that I am moving and dividing some now because we still have at least six to eight weeks of the growing season left before temperatures drop and growth slows or stops over winter. That said, I have done this in winter and we can get away with it but it is not recommended in less benign conditions where the plants may just sit and decompose in sodden, cold soils.

Learning from experience: gardening with bigger grasses in NZ conditions

Late March, so autumn of the first year.

We know quite a bit about many aspects of gardening, particularly shade gardening, but gardening in full sun with big, bold perennials is a whole new ball game here and a steep learning curve. I mentioned a couple of weeks ago that I planned to lift and divide the larger growing grasses that I have used in the new borders.  Of course I am only half way through it. These jobs always take longer than I plan, even factoring in other distractions. But it is interesting to stocktake the performance of these bigger grasses one year on from planting.

Stipa gigantea falls apart into divisions when lifted

Stipa gigantea – the giant feather grass or golden oats. Yes it grows quickly and enthusiastically but is very easy to dig out (not strong-rooted) and pretty much falls apart into divisions when lifted. So it is easy to manage. The flower heads are the feature but while ours bloomed, the sparrows laid waste to them so we did not get the full glory last summer. As far as we can make out, it is sterile so seeding and invasion are not an issue.

It is hard to beat the miscanthus at any time of the year

Miscanthus – I think it is ‘Morning Light’ we have. It required a little more effort to dig it out and an old handsaw and small axe to separate it into pieces but was not particularly difficult. I would not want to leave it too long though, before digging or it would get beyond my physical limits to dig and divide without assistance. It has been a standout. The clumps stand tidily like sentinels and it is brilliant at all stages – the foliage and the plumes. It is the only fully deciduous large grass I am growing and even the pillars of dried foliage have been attractive all winter. It is also close to sterile, setting almost no seed.

Is it Chionocloa rubra? Someone will know but it is a native tussock at least.

Chionocloa rubra – there is a bit of a question mark over the name of this one but a couple of visitors have suggested this identification. A native tussock grass that is performing brilliantly so far in attractive vase-shaped clumps. It is easy enough to dig and divide (more hacking apart with saw and small axe than dividing, to be honest) though I only divided this year to get more plants. It won’t need as much active management as most of the other grasses.

Anemanthele lessoniana is another native grass. It was a little underwhelming in its first year but I am told flowers attractively once established. I started with just three plants so I have divided them after their first year to get more.

The native toetoe (now an austroderia though formerly a cortaderia – our environmentally friendly version of the invasive Argentinian pampas grass) was one I planted a little anxiously, worried about its potential size. I need not have worried. The resident rabbits love it so much that the poor little things have failed to make any headway. I shall have to construct little cages over them if I want them to get any larger. I see we have five different austroderia species native to NZ though which one this is, I am not sure yet.

It appears I failed to photograph the calamgrostris at is peak but it is the third one up on the left in this May scene of late autumn.

Calamagrostis ‘Karl Foerster’. Yes well, this one may be on borrowed time. It is scary. I bought several – I can’t remember if it was 5 or 10 because I divided a couple of clumps mid-season when it was clearly growing strongly (about now, alarm bells should be ringing for experienced gardeners). It is a stock grass for the contemporary perennial gardens we have been looking at, mostly in the UK. Our Canberra daughter also said it was the stand-out grass in her little prairie-style patch. And it was most attractive all summer and autumn. Not so in winter where it has been a messy mix of green and brown. It is deciduous in colder climates but not so here. But that is not the main issue.

Added bucket for scale but I also measured and the root systems reached 45cm across in one year. As a quick aside, my kneeling pad of the day is a piece of rubber carpet underlay cut to size. It doesn’t last that long but it comes from waste destined for landfill anyway and while it lasts, it is good.

The plants I bought came in 2.5 litre pots so larger than a liner but not big. Under one year is all it took for each plant to e x p a n d from about 12 or 14m across to somewhere closer to 45cm across. It took every ounce of my determination and strength to dig out the clumps for they were going deep as well as wide. The root ball is solid and dense and that is when I went to find the axe to chop it apart. I raised my eyebrows and started replanting just a few smaller – much smaller – clumps and these reduced in number the further I went. Most are piled to compost. The clumps I replanted are on trial for one more year but in my bones, I know they are on borrowed time. In our conditions, it is just way too vigorous though I am guessing that in harder conditions with dry summers and cold winters, it may just be deemed a ‘strong’ grower. I don’t know if it seeds but I am not seeing seedlings pop up so far. I would say that it may be quite useful if you want to retain an eroding precipice quickly but as a garden plant, try it before getting too carried away. I think I will decide that its powerful growth outweighs the charm of its flowering plumes.

I haven’t tackled the Elegia capensis yet but it can stay untouched for another year. It is a restio so not one of the grasses, though its growth habit and bamboo-like appearance mean it fits a similar niche in the garden. I know from experience that this is one we can contain if required by cutting around with a sharp spade to reduce its spread.

The smaller grasses can wait but the standout smaller variety so far has been a very dark green form of the Australian lomandra. We have several named forms and I am hoping I will unearth the labels when I lift the clumps again (I hate looking at visible plant labels so I tend to push my labels in so deep that I can’t find them again) and the dark forest green one is by far the pick of the bunch. The rest are a bit… utility, shall I say?

The takeaway lesson from all this is we need to trial plants here. That key plants used widely overseas perform differently in our conditions. It is why we buy garden books that cover design, history, philosophy and contemporary trends but never books written by overseas authors which focus on recommended plants and planting schemes. There is no substitute for local experience.

Postscript: I have finally found a home for the Dutch irises. They always looked a bit crass and coarse in the rockery and other areas where we concentrate on species and dwarf bulbs. But they are perfect with the big grasses, Just the right scale. And they bring in colour now in early September when there is not much else happening in that area.