Garden School:


Garden School:
Teaching this week: Rose pruning (as always!) and water management

Friday, 28 March 2014

Potbound plants: how to deal with them

What exactly is a pot-bound plant?

Ans, one which has been in the pot for too long. This frequently happens at nurseries: if plants don't sell, they are kept for another year, and instead of being potted on, which means being removed from the pot and put into a larger one, they are left.

Why? Well, because potting on involves money - the cost of the new pot, additional compost, and someone's labour to do the work. It will also need relabelling, and if it has a posh printed label stuck to the pot, this could be expensive.

So it's easier for nurseries to leave them where they are.

The problem is that the roots keep on growing, and when they meet the inside of the pot, they start going round and round, forming a tight net of roots. Then when the plant is bought, taken home and planted, it struggles to get any roots out into the soil.

Here's one I was presented with in January:

This is the classic warning sign of a pot-bound plant: the thick tuft of roots growing out of the bottom.

If you are lucky, you can tap the pot rim enough to loosen the plant within, then "wiggle" the whole thing out without damaging the bundle of roots. 

More often, the only answer is to cut them off in order to get the plant out, which is what I had to do here - when I picked it up, every single hole had a tuft of roots like this one, and I was nearly finished before I thought to take any photos.

Even after cutting off the tufts, sometimes the plant is so securely stuck in the pot, you may have to cut the pot off the plant!

That was the case on this day - the roots were sticking to the inside of the pot, and it just wouldn't budge.

Normally, my first move is to hold the pot upside down in one hand, and bang the rim of the pot on the other hand, which usually dislodges the plant.

Not today, it didn't.

The next move is usually to find something like the edge of a wall or a step, and use that to bang the pot more convincingly.

In this case, it was a small shrub, and it wasn't possible to get the right angle to do so, without risking damage to the plant, so the only option was to remove the pot. Out with the secateurs, slide them carefully down inside, and chop chop chop.

The roots still refused to let go of the pot, so I had to cut it away in sections, as you can see here.

Generally, once you get over half-way round, the rest will peel away in one sullen lump.

In this case, I had to cut right across the bottom as well, before it would come out.


Once the plant was released from the pot, the next job was to get rid of some of that mat of roots.

I know it seems extreme, but those roots which have been circling the edge of the pot are rock hard and bone dry, as they have been "baked" against the inside of the pot for months.

They don't help the plant to take up nutrients any more, and they prevent the smaller roots from working their way out into the soil when you plant it.

So the answer is to gently - or not so gently, in this case - pull them out of the "pot" shape. You can see on the bottom where I have "fluffed  up" the roots,  and I then did the same to the sides. You can use your fingers, or a small hand-fork, and in my experience, you can be quite firm with them.

Sadly, typically, I forgot to take a final "after" picture, as I was rushing to get it safely in the earth, but I hope that at least you can see the principle.

Saturday, 22 March 2014

Today's mystery: the Ivy Tree

Ivy: love it or hate it, gardens are full of the stuff, and if ignored, it tends to get a bit carried away.

There are two sides to the argument about ivy on trees: some say that the ivy does not harm the tree, as it only clings for support, it's not a parasite, and does not take any nutrition direct from the tree.  These people will also point out the beneficial effects to bees of having pollen available in the autumn, and to birds of having berries available in the spring, not to mention the vast amount of wildlife living in amongst the shelter of leaves and stems.

Others will point out that a cloak of ivy can ruin a tree by making it top-heavy in winter, when leaves are normally shed to prevent wind damage: it masks the shape of the tree, ruining it ornamentally, while also making it impossible to assess the condition of the tree.

Anyone that has every pulled away a shield of ivy will know that it is full of woodlice, beetles etc, all of which infest the bark of the host tree: the ivy's aerial roots might not in themselves damage the bark (although I would dispute this, having seen ivy removal taking the bark off with it) but they keep it soft and moist, allowing burrowing insects to get well inside it. This cannot be good for the tree!

There is also the point that although the ivy might not be directly parasitic, it will have its roots in the ground immediately adjacent to the host tree, and will therefore be competing strongly for the same nutrients and water.

And as for the wildlife... I would urge anyone who thinks we should incorporate a wild patch of nettles and ivy in our gardens "for the wildlife" to look over their fences, to go for a walk around the back alleyways and footpaths of their town, to check out the canals, used and disused, to look in hedgerows - you will find masses of nettles, ivy, and other weeds, all flourishing beautifully. There really is no need to sacrifice an isolated patch of our precious garden, when there are acres of wild land all around.

So, you might possibly gather that I'm not a big fan of ivy in gardens.

And never more so that when I found this poor little thing:

 "What the heck is it?" you ask.

Well, I can tell you that the upper branches are some kind of Japanese Acer, there is a massive, badly-shaped box "lump" to the left, and a dwarf conifer behind it.

But as for the ivy-covered area - it was impossible to tell.

So I set to work, carefully untangling the ivy from the upper part of the tree, following it down to the ground, and cutting it away in sections to avoid damage.

After a while, I hit rock! Bizarre, I thought, Japanese Acers don't usually grow out of rocks?

Gradually, the stem of the tree appeared from the dense cover of ivy - it was growing at an extraordinary angle, over the rock, apparently in a desperate bid to avoid being smothered by the encroaching Box to the left.

Here is the result:

Much nicer!

Once I could see what I was dealing with, I carefully cut back the Box "lump" to get it clear of the Acer's stem, and I removed much of the conifer's dead brown undergrowth.

Over the next couple of weeks, I will be reshaping the Box completely - past gardeners had hacked into it to allow room to walk past it, with no thought for the overall shape. I intend to make it back into a round ball, as that was presumably the original intention.

Can you imagine what the Japanese Acer is thinking?

It's either taking a deep breath, for the first time in years, and saying "Ahhhhh! Lovely!" or it's screaming "Don't look! I'm naked!" in panic.

Friday, 21 March 2014

Strip the Willow... it's Pollarding time

It's time for a particular Willow in my care to have its annual pollarding, which I normally do every year (as you would expect for an "annual" prune, ha ha). Except that I didn't get around to it last year, so it's a bit hefty. But no matter, with my trusty bowsaw, my loppers, and my extending saw, I bravely went forth this morning, to do battle.

What is pollarding? It is the rather drastic pruning of a shrub or tree, at the same height every time it is done, either for ornamental purposes, or for promoting long straight growths at the selected height, usually for use as a crop.

Pollarding and coppicing are the same thing at different heights, in case you've ever wondered: coppicing is ankle height, pollarding is usually somewhat above head height, or - in urban streets - at about lamppost height.

As well as producing the required new growth, it keeps the tree or shrub down to a manageable size, and extends the life of the plant almost indefinitely - a regularly coppiced tree will never die of old age.

In this case, it's ornamental, as the Willow would otherwise get so large that it would obstruct the view of the lake from the front lawn, so most years I chop off all the long growth, opening up the view and promoting a flush of new, fresh growth.

There is a minor complication in that the tree is growing right on the edge of the lake, so I can only get to it from one side. This means that some of my pruning cuts are a bit ragged, as I am leaning precariously and having to cut at whatever angle presents itself, but as it's only Crack Willow (Salix fragilis) I don't worry too much about it.

Here is before, looking pretty in the early morning sun:


And here is "after":


My client appeared as I was halfway through, and commented "We always know where you have been!"

As usual, it took me longer to clear away the mess than to do the work: here's a sort-of panoramic shot of some of the off-cuts:



The bonfire pile is now huge again, but I have tucked the thick straight poles behind the pump house, in case they come in useful...

Monday, 3 March 2014

Whoops! There goes another tree.

It's been a winter for trees falling over - so many storms, so much water. Trees can only take so much, and then they snap - literally!

Last week I arrived at work to find that one of the old Plum trees in the meadow had snapped right off, about 10' up:


So where was the top of it? Answer, lying on the ground:


"Oh dear," said my Client, "what shall we do with it?"  Knowing that she loves sculpture and used to have several dead tree trunks lying around the meadow, I made the obvious suggestion that we should chop off the small branches, and keep the main thing as a living/decaying piece.

Half an hour, with my trusty bow saw, later:


It's the Tarantula of Doom!

The amount of smaller brushwood that came off was astonishing, I made three heaps of it, each easily as big as the current bonfire heap - here's one of them (right).

We agreed it would be better to get the bonfire heap burned off first, then move these piles across, otherwise it would make a huge wobbly heap, which might be a little intimidating for the Client's husband, who loves to do the bonfires, but who is always concerned that if it's too big, it might get out of control.

I expect that I'll be asked to reduce the Tarantula in size once we've had a chance to assess it: at present it's a little too big and sprawling, so I anticipate a fair amount of "fettling",  to get it into shape.

Although I do think the Tarantula is quite amusing!

Sunday, 2 March 2014

Cotoneaster pruning

This was a fun job - the client had a large shrubby Cotoneaster growing beside the house, which had extended itself over the path, to the point where they could barely squeeze past it.

 It was also completely swamping the raised bed - from this perspective, behind it - and under cover of the foliage, there were half a dozen Elder trees growing, along with a mish-mash of general weeds, all of which were growing pretty much unseen under the mess of Cotoneaster.

Which, to clarify, is pronounced K'tony-aster. Not cotton-easter!

The most familiar one is Cotoneaster horizontalis, whose branches grow in a flattened herringbone pattern, and which can be found ascending up walls. If not supported by walls, it just sprawls wider and wider, but like all of these shrubs, it produced masses of berries, and is therefore valuable as a wildlife feed plant.

I don't know exactly which Cotoneaster this is - it's hard to tell with the deciduous ones, in winter - but it's quite free-standing. It may even have been a chance self-set seedling, as it is planted in a rather odd position. I suppose it's possible that the plan was to have something to break up the sightline from front to back...

Regardless of the species or origin, the treatment was simple - get underneath it, remove all dead branches, remove branches that were too low to the ground, remove branches that were obstructing the path, and those overhanging the bed: then remove a similar amount from the other side, to retain some balance and proportion.

 Here's the result: now we can walk along the path, and we can see the raised bed, and the invading Elder are no more.

The whole process was somewhat similar to the Salix caprea Kilmarnock pruning which I wrote about earlier - rather than just chopping off the bits that get in the way, it's far better to go right back to the main stem of the tree/shrub, and clear it out.

As a side benefit, you often get a nice view of the stem - in this case a rather interesting wind-blown arrangement of stems, almost Japanese in style, possibly?

And here is the pile of branches which I removed - very nearly the same size as what was left!

As I said, a fun job - I enjoy having a good chop now and again, and it's very satisfying to bring a sense of order to a chaotic shrub.

Saturday, 1 March 2014

Silly Snowdrops

Apparently snowdrops are becoming big business again: there were reports in the Horticultural press of people paying £360 for one snowdrop bulb. One!!

OK, it was a particularly rare one, called "Mother Goose" and as you can see, left, it's mostly yellow, instead of the usual white and green.

But still, £360?

Would you pay that for one bulb? What if it died?

Personally, I'm not that fussy about my snowdrops - I love them all, they are so cheerful at this time of year, and if I have a favourite, it would be the common or garden Galanthus nivalis, double flowered version, Flore Pleno.

One of my gardening colleagues is a big Galanthophile (that's the name for snowdrop lovers, apparently) and she got quite excited about these rare ones, although she draws the line at paying £360 for one.

To amuse her, I sent her photos of two "unusual" snowdrops in my garden which I thought might interest her:

The one on the left is Galanthus nivalis "Grumpii" and the other is "Blue Moods".






*snorts through nose, and puts felt pens away*