Garden School:

Garden School:
Teaching this week: Rose pruning (as always!) and leaf mold.

Monday, 15 January 2018

Let's do some Prairie Planting!

...said my Client.

I love it when a Client gets hold of a Piet Oudolf book, or reads about the New York High Line, and is inspired to have a go themselves - but there are some gardens (notably the smaller ones) where it just isn't possible to go the whole hog.

Why is this? Because proper prairie plantings, like wildflower meadows (which are a watered-down version of the same thing) are massively more work than they sound - it's not trivial to get one started, and once you start, the maintenance is far from a "once a year chop". There are ways to achieve the same effect, but they are not low maintenance.

The problem seems to be one of scale. Here in the UK, our gardens are small: to make any sort of wildflower meadow you need at least an acre to get a good effect - wildflowers are light and airy, with small flowers on long bare stems, so you need a certain density of them to get any sort of block of colour. This is radically different from our cultivated, highly bred, garden plants.

You also need enough acreage to absorb the inevitable bare patches, thin patches, poor underlying soil condition areas, parts where an inelegant weed has crept in and smothered the chosen planting,  and so on. Again, you need to be looking sideways across an acre of it, to get a decent effect.

And most garden owners simply don't realise what the books mean when they say that a wildflower meadow, or an area of prairie planting, is "fabulous from mid summer right through to early winter".

What this really means is "it looks dreadful from mid winter right round to mid summer".  And when I say "dreadful", I mean this in the context of an owner looking out from their kitchen window and being  unable to avoid seeing it. All that lovely prose about leaving the seed heads to provide visual interest through the winter, and nourishment for wildlife, sounds so good in summer, but invariably by mid winter they are tired of looking at bent and battered brown stems.

It's all right for these big estates, where you can simply view them from afar, and not have the close-up view: but in small gardens, we really need a different approach.

This all came up again recently, when one of my favourite Clients wanted my input on an article they had read about prairie planting. Luckily for them, they have the space in which to do it properly, but in most of "my" gardens, it can be problematical.

The article is a very nice one, mostly focusing on how Piet Oudolf's biggest impact is to take his style of prairie planting out of private estates, and to get it into public areas. The article quite correctly reminds us that, up until a few years ago, public planting was all very much the same: large areas of lawn, a few specimen trees, and a bank of shrubs, with some herbaceous perennials if you were lucky, that would be cut right back in September, leaving the beds "neat and tidy" for 6 months.

(The article omits the UK's obsession with municipal bedding plants, but as they are also generally ripped out in late autumn, they fall into the same general description.)

The revolution, led by Piet Oudolf, is that prairie planting need not be labour intensive: if the public can accept that overwintering brown stalks have a certain beauty of their own, then with a once-a-year clearance,  his style of planting could be introduced to many more public areas.

Me, I'm not so sure: as it says in the article, "Piet’s gardens show us why that effort is worth it.” Note the word "effort".  It's not low maintenance, it's not trivial - it's an effort.

And you'll note that in the section about the High Line, they comment that visitors used to ask "Are they going to cut down those dead flowers?”  The author also says "What many people saw was a park full of weeds". This tells you a lot about what is involved: it does look like a park full of weeds, and it is full of dead flowers, because you can't get in there to deadhead, and also - of course - you can't expect it to reseed itself if you take off the seedheads.

The author says that, seven years later, "I’ve watched public perceptions of what a garden is change dramatically.” In my opinion, being someone who reads the horticultural press and keeps up with the horticultural trends (for which I would point the reader to ThinkinGardens - Anne Wareham's website and forum for intelligent gardeners), I would say that there are two points here - firstly, "people" are learning that, if they want to sound well-informed, they have to say that they admire the High Line, even if they hate it: and secondly, it is an accepted fact that we all resist something new at first, then we get used to it, then we start to like it, then we accept it, then we reach the stage where we can't imagine life without it.

So how does all this relate to our little gardens in the UK? We can't quite do the same broad sweeps of planting, so the usual interpretation of this style is to plant a bed with large clumps of grasses, interplanted with large clumps of perennials, and an over-planting of annuals: usually poppies of some kind. It's very much a compromise, based on Oudolf's ideas, but adapted for our climate, small garden size (compared to his) and weed competition..

Here are some photos of one of my former gardens (alas, they moved away),  which had two very large prairie-planting beds.

Seen from a distance, they are a pleasing mass of waving grasses - very "prairie" - of head height or more, interplanted with suitable herbaceous perennials, and fronted by a fringe of low-growing thuggery, Alchemilla mollis by name .

I always thought this last plant was completely out of keeping with the rest of it, but heyho, the owners liked them.

Close to, you can see the marvellous interplay of the blocks of feathery grasses with the strong colour of the Echinacea (Coneflower).

From another angle, a month earlier, we had the poppies, carefully resown every year by yours truly, seen rather dramatically through the drooping flower heads of the Spanish Oak Grass.

Beautiful, huh?
Here's another view from the back, showing the Miscanthus just flowering nicely - the purple haze - in mid-summer. with a chosen mix of Opium Poppy filling in the gaps.

We left the grasses etc uncut all through the winter, "for the frost display" (I am rolling my eyes at this point: it's a running joke in gardening circles that every magazine bangs on about the beauty of the frost display, but in real life, you are more likely to get a tangled, blackened mush), but most years, by about early January, the owners were pleading with me to chop it all down and "tidy it up".

So in effect, it was just another variation on the classic herbaceous border, but with large grasses providing the backbone, instead of shrubs.

And it was just as much work to maintain as a normal, well-established herbaceous border: some plants would suffocate others and would have to be lifted and split, some would be crowded out and would need rescuing: some gave up and died, and would have to be replaced each year , which is not how I like to garden, but when the Client knows exactly how they want it to look, and are prepared to pay to replace plants every year, well, *sigh* we just get on and do it.

Getting back to the High Line, I'd like to mention something which I think is often overlooked, which is that the High Line started as naked concrete - they scoured out everything, brought in clean soil and planted it, with very little weed competition. And being surrounded by buildings, in an ultra-urban setting, there don't have quite the same amount of weed seeds that we do, in a normal garden.

In the same way, most of the new gardens in the Oudolf style are converted meadow, ie they don't have any perennial weeds. Again, they have the luxury of space in which to work, and can bring in the diggers and scrape off most of the topsoil, leaving the depleted soil which wildflower meadows - and most prairie plantings - require.

Here, however, we are usually trying to convert a piece of existing garden into a mini-prairie, and - as with so much of life - preparation is key: if  you don't get rid of all the weeds before you start, you are never going to have any sort of low-maintenance planting.

So, if you'd like to have a go at creating your own Piet Oudolf planting, what do you need to know? Here are his basic principles.

1) Plant for all seasons.  Just as you do with your normal herbaceous or mixed border.

2) Shove in lots of tall grasses. Fluffy-headed stuff such as Spanish Oat Grass, and some sturdy upright Miscanthus.

3) Plant them in rivers. Not in neat triangular blocks of 3 and 5, as we are taught, but in flowing, snaking rivers. This needs big spaces, and a big budget.

4) Structural plants - well over half, nearly ¾ of the planting should be stuff that can survive at least until late autumn. In the normal UK garden, that would be "shrubs".

5) Repetition: if you find something good, it's worth repeating it. This is far from a new philosophy in gardens, in fact it's one of the mainstays of British formal gardening, and there's a reason for that - it works. So once you have worked out a nice grouping of plants: say, one Spanish Oat Grass, flanked by two Miscanthus sinensis 'Zebrinus' (I'm a bit biased here, as I love that last one) with  some Coneflower in front, and a clump of Eryngium to the side, repeat that "set" of plants at intervals along the way.

6) Plant with wildlife in mind: plants don't have to be "native" as such, but think about the bees and avoid over-bred fussy flowers. Simple flowers, open unto the birds and to the sky, look better and please the pollinators.

7) Layering: have a balance between tall stuff, mid-height stuff and low-level planting. Try not to do the standard UK formal "little ones at the front, big 'uns at the back", not least because prairie planting is intended to be viewed from all sides and - if your garden is big enough - from inside as well, by having narrow snaking paths through the planting.

8) Blur the edges. Let them self-seed and intermingle. This is much harder than it sounds, as within a couple of years you will find that you can no longer walk around within it, and that's when the ground elder, brambles, cow parsley and bindweed inevitably find their way in.

9) "Learn to love brown". Ugh.

10) Don't use small plants: a two-fold principle, in that you need to start with decent-sized plants in order to prevent the thuggish ones swamping out the less vigorous - and you also should avoid small-scale plants such as delicate Tellima, or low grasses such as Ophiopogon.

11) Don't be afraid to use fillers: the much-despised (by me!) fringe of sturdy Alchemilla mollis at the front of a prairie bed can hide a multitude of sins, and a fistful of Poppy seeds each spring can create an ephemeral gap-filler for later in the year.

12) Choose your plants to be of an appropriate height: many of the "usual suspects" for this type of planting get way over head height, especially if your soil is strong and rich. In a smaller area, try to choose perennials that will hit the heights of 3-5' and - fingers crossed! - will stay there through the winter

Do you  know, having written all that down, I now have the urge to recreate those curved prairie beds: they were rather lovely. Hmm, let me think, I wonder which Client would be open to the suggestion?