Garden School:

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

Friday, 2 February 2018

Salix Kilmarnock: what to do with a very old one.

I've written several articles about this pretty, weeping tree, but here is a slightly different question regarding their pruning and maintenance.

A nice lady called Marie sent me photos of one which they had inherited: it was very old, and was lying down instead of standing up.

Bravely, they heaved it upright, knocked in a firm stake, and propped it up. Here's the result:

There are several points to mention: firstly, a lot of people ask me about the grafting point, and here's a perfect example, as you can very clearly see the graft - that's the big lumpy bit, just above the angled stake. That's where the weeping part has been grafted on to the upright non-weeping trunk, and it marks the point below which nothing must be allowed to grow.

This must be a very old one indeed - just look how thick and gnarly it is!

Secondly, I would normally faint with horror at the idea of knocking a metpost in quite so close to the trunk of a tree: usually, if you tried to do this you'd be unable to get a stake in the ground at all, as there would be roots all round the tree.

However, in this case there was the rotted remains of the original tree stake, which meant that Marie was able to hammer the metpost in to the old stake's rotting base: so there was already a vertical "tunnel"  in existence, which the tree roots would have grown around.  .

(In case you don't know what a metpost is, it's a metal square-section stake , with a hefty four-angled point which is well over two feet long: you hammer them into the ground (*faints with horror again*) then you add the wooden stake. Brilliant for fenceposts, as it saves having wood underground, which tends to rot. Not usually used for tree stakes, but when the devil drives....)

Right, back to the plot: point three: the prop. If you have to have a temporary prop such as this, it's a good idea to pad the trunk of the tree with some fabric, to reduce damage to the bark. No matter how firm the stake, the tree will move slightly in the wind, and will rub across the top of that prop. So a bit of padding will reduce the damage. I use old dishcloths, or towels: something fairly thick and squidgy, and preferably something cotton. And, of course, remove the prop as soon as it is no longer needed.

Four: the actual ties around the stake. They will need to be tight, as they are holding up the whole weight of the tree: this is good, as it means they won't be rubbing the bark. On the other hand, you will need to check them every month or so to ensure that they are not too tight. It's easy to forget about them, and two years later you find that the trunk has tried to expand, and now bulges above and below in muffin-top fashion. This is very bad for the tree! So - and this applies to EVERY tree you have which is staked - it's important to periodically go round and check that the ties are not cutting in.

Usually at this point I feel compelled to mention the importance of having a separator between the stake and the trunk, to ensure that they are not rubbing together: but in this case the tree is leaning heavily away from the stake, so that's not a problem! Also, there is a twist in the tie, which is perfect, as it works as a buffer, and also creates a little slack in the tie to allow for a bit of expansion.

Fifthly (still not sure if that is a real word or not) I should mention that there is an inherent danger in trying to straighten a leaning tree: there is a very real risk of damaging the roots. Half of them are going to be bent at a sudden angle, and the other  half are going to be ripped out of the ground, in order to get the trunk upright again. Sometimes this is fatal, sometimes not so much: if the straightened tree is very firmly staked, and the loose earth well pressed down, then the roots will often be able to recover from the shock, and it will re-root in the new position. Fingers crossed for this one: it was done a month ago and it's showing signs of buds, so that means "so far, so good".

Next, Marie asks how to prune the canopy to get it back to looking lovely again.

As you can see, now that it's upright, the canopy is extremely lop-sided, so it is going to need a fair bit of work.

The first thing to do is to remove as much of the dead wood as you can.

How to know which bits are dead? They will be grey and hard, rather than any shade of browny-green, and will be slightly soft to the thumbnail. Dead wood won't have any buds at all - so if you are not totally confident of your ability to tell the difference, wait a couple of weeks until the buds begin to break open.

Once you can see that some of the branches have buds visibly opening, it's easy to find the ones with no buds at all, and remove those ones. Start at the tip, and follow the branch back and back and back until you find some buds: if there are none, then you will follow it right back to the trunk, and that is the point at which you cut it off.

There is no point leaving dead wood on a tree: it will rot, and may lead infection into the rest of the tree.

Having removed all the definitely dead material, it's then time to step back, take a look at the overall shape and decide how best to make it even.

As described in detail in the other articles, this is normally done by crawling underneath it to remove inner wood, leaving the outside - which is the most actively growing material - to form the canopy.

In this case, at least the owners won't have to crawl on hands and knees!

I would certainly want to get all the smaller branches well clear of the ground, and in this case that will mean taking a fairly drastic amount off the "downhill" side. Don't just chop across like a pudding-bowl haircut, take the time to remove individual branches, leaving the shorter, fresher ones.

We are aiming for a "light, airy waterfall",  so although it might seem a bit drastic to remove a lot of the wood, it will soon grow back: all Willows are famous for their speed of growth.

And by reducing the lop-sided mop, it will take a lot of weight off the trunk, which will help the roots to stabilise, and will thus mean that the ugly diagonal prop can be removed as soon as possible. (If it were mine, I'd paint that prop dark brown, or at least smear it with mud, just to reduce the impact of it.)

Is it possible to see a bit of almost Bonsai-like oriental grace in those twisty stems?

It's certainly an unusual view!

So, having cut off the dead stuff,  shortened the over-long ones, thinned out the remainder, what is left to do?

Answer, give it a good fistful of food - a balanced food such as Growmore, or a watering-can full of  seaweed feed, or fish, blood and bone - and a good drenching.

Continue to water it twice a week from now until mid summer, even if it rains, and feed it once a fortnight or so.

Hopefully, it will be invigorated and will put out a good flush of new growth: and Marie, do please send me a photo of it in mid-summer, I would love to see how it performs!

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?