Garden School:


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

Tuesday, 29 November 2016

Do we need to water new plantings in frosty weather?

I've had two questions on this subject in the last two days, and it's quite an interesting subject, so I thought I'd answer it in detail.

The first question was "With frost forecast for tonight, should I still water new plantings?" and the second was "Should I plant these newly-bought plants out now - late November - or leave them in their pots until spring?"

Taking them in reverse order - firstly, then, is it advisable to plant out new plants now, so late in the season?

Answer: yes. It is fine to plant out at any time of year, unless the soil is actually frozen. If you think about it, those plants in plastic pots are going to have cold frosty air all the way round them, on all sides, and on the top, but if you plant them in the garden, then they are protected by soil on all sides except the top - so on balance, plants are safer being in the ground, than being in pots.

Generally speaking I would prefer not to plant things out when we are in the middle of a cold spell, but it can be done,  as long as the soil is not frozen solid: a thin layer of frozen crust is not a problem, if the soil below it is still friable, and friable, in gardening, means that the soil breaks up into small crumbs. You can easily test this by trying to dig an 'ole in the soil: if you can't get the trowel in, or if all you can do is lever up one enormous wodge of solid soil, then it's too cold for planting!

However, if you break through a surface crust and find that the soil below is easy to work, then it's fine to plant out - there's a difference between a couple of mornings of frost, and that situation where it's been below freezing for day after day... that's what I would call permafrost, and there is simply no point trying to plant anything when the soil is frozen solid.

There is also a halfway house, if the soil is not really friable any more, but you still want to give them some protection : you can "plunge" them, which means putting the plant, still in the pot, into the ground up to the rim of the pot. The hole does not need to be a perfect fit, air gaps don't matter because the roots are still within the plastic pot, so even if the soil is horrible and hard, you can still chop out enough of a hole to slot the pots in, ramming the chunks back in around the pot as best you can.  This means that the sides and bottom of the pot are protected by the soil from frost, but they can easily be moved later, or next spring, into their permanent positions. Just don't leave them too long, otherwise they will root through the pots! Ask me how I know this happens...

...answer, a Client asked me to remove a large-leaved ivy when its supporting tree had to be cut down (hence the sawdust everywhere in this photo) and when I cleared away the mess, having cut off the top-growth, I found that it was still in a pot...

and when I lifted the pot, I found the ivy had completely shattered the bottom of the pot in order to get roots down into the soil!

Anyway, back to the questions:

Secondly, do I water new plantings when cold weather is forecast?

There are two aspects to this question, firstly there's the plant's point of view, and for the plant, it is usually best to water in new plantings, even on cold wet days, as the deluge of water helps to settle the soil around the roots, or around the pot-shaped root ball: air gaps are the worst things for plant roots, leading to root death, which is why we firm down the soil around them when we plant them.

They don't need as much water as we would use in summer, and generally speaking they won't need any extra watering over the first few days, as you would in summer, unless - when planting them - you observed that your soil is bone dry, in which case then yes, you will need to water the new plants for the next week or so. 

But if the soil is dark, and damp to the touch, then other than the initial "settling in" watering, no, you don't need to water them again.  (Although it's often a good idea to give them extra watering next spring, which is when they will start to actively grow.)

The second aspect of the question relates to the possibility of the water, if you have watered them, freezing overnight. Will this damage the plant? Answer, no: this early in the winter, even a hard frost will rarely reach more than an inch down into the soil, and most of the plant's roots are well below that level. 

We have all read that lovely suggestion about digging our vegetable plots over roughly in autumn and leaving the clods to be "broken down by the frost" which is absolutely true: the frost will freeze the water in those clods of soil, the water expands into ice and breaks up the clumps. But you will note that this only occurs on the surface of the soil, that's why we have to turn over the soil into colds, exposing it to the cold frosty air: and it can take all winter for there to be enough frost to work the magic. The plants, meanwhile, have their roots all a few inches further down, safely protected from the effects of the frost.

There, I hope that's answered a couple of questions: do please feel free to email me with questions, I love getting them!

As for the actual frosty mornings, I suppose you could look on it that when that frost melts, mid-morning, it does provide a bit of gentle watering for everything below!

Friday, 18 November 2016

BSBI: why are people not joining?

A few days ago I asked this question:

Here's a question for all fellow botanists out there: why are you not members of the BSBI?

I don't mean that in a tub-thumping "Why the hell aren't you a member!!" sort of way, I mean it in an "I know why I personally have chosen not to be a member anymore, but I'd be interested to know what other botanists, both beginners and improvers, think about it" sort of way.

Why do I ask?

Like many organisations, the BSBI (Botanical Society of Britain and Ireland) is failing to engage younger people, and failing to increase membership. They are trying to address this by updating their website to be more whizzy and modern looking, and by promoting themselves as follows:

"We support all botanists - beginner or expert, amateur or professional - as they identify, record and map what grows where"

So they are clearly interested in getting new and younger members, but they don't seem to have a clue about their own shortcomings.

Having asked this question, I received quite a few responses, including some slightly huffy ones from the BSBI themselves, so I do apologise to them if they thought I was being a bit rude about them!

There were several general themes which arose repeatedly.

One was the cost - well, everything costs, these days, and I don't think £30 a year is unreasonable, especially as they have a concession for students up to age 25 (25!! Still studying at 25!! ) which reduces it to just £12.

"They don't let you sign up online" was one objection, but that's no longer a problem, you can now sign up direct from the BSBI website, using Paypal or a credit card.

Then we had a whole raft of "The publications are too academic/dull". Well, fair point, but they do make it plain that the Journal (which is so intensely academic as to be of very limited interest to a more "general" botanist) is specifically an academic publication. The "lighter" publication was, when I was a member, called BSBI News:  it came out three times a year and contained what they called "notes", which appeared to be contributions that were not sufficiently academic for the proper journal. These were mostly, in my opinion, only of interest if they happened to be about a plant in which you were already interested, or which was your specialist subject. There were few that related to botany in general, very little that were of any "use" to beginners, and virtually nothing with a sense of humour.

When I first joined the BSBI I wrote suggesting that they should have a section specifically for beginners/improvers, with light-hearted, short, pieces:  they eventually replied that they considered the News to be perfectly appropriate for such people. I think they are wrong, and that if they really want to engage new and/or younger people, they need to create some sort of induction route, involving a section specifically for new people, and maybe a list of useful terms - which led on to the next point.

Several people commented that "the jargon is inpenetrable for beginners."  Well, I have to agree with this one, when I first joined, I simply could not work out what a monad was, or a tetrad (four monads?) or a quadrat or quadrant: it didn't seemed to be written down anywhere.  It's as though the BSBI expect us, having joined, to spring, fully formed, into being: au fait with their jargon, and ready to submit records! That could do with a bit of work.

"They're all old fuddy-duddies"  was, I'm afraid, quite a common response.  There is indeed a common perception that botanists are all silver-tops, but I have to say that the BSBI do seem to be trying to present themselves in a more modern way these days, and they are certainly plugging their Twitter/Facebook links.  I suppose the only real solution to this perception problem is to get nature rambles back on the school curriculum, and I think it would take more than the BSBI to do that.

One interesting comment was "What does BSBI offer members that they don't offer non-members?"  Well, if you check their website, they give a whole long list of benefits of joining, including the already-maligned Journal - yawn - and the  "News" magazine, which is now available online to save costs. Then there is access to an "expert" in the form of the VCR who can make a ruling if you are uncertain about a plant identification (well, good luck with that, hope you have more success in getting a response from yours than I did from mine), opportunities to submit records (which rather assumes that you already know how to do it), and they do offer training courses, and grants; the one overwhelmingly positive response I received was from a young chap who had just been given a grant. But most of their benefits relate to recording.

Other comments include the perceived emphasis on recording squares, rather than anything more ecological: a suggestion that they are selfishly restricting access to their scientific literature, which could all now be put on line: being orientated on field botany rather than other academic activities (? not sure what that person meant - perhaps they thought the BSBI should do research? GM? ), and a comment that "They'd be more useful if there was a convenient means of taking a floral formula and finding a list of taxa possessing that formula".

All of which is very interesting.

One final point to be made is that we keep hearing about this ageing membership, and that "all the experts are elderly".  Well, expertise is something you accumulate over your lifetime, so of course the experts are elderly. It would be more worrying if the experts were all teenagers, as one person so perceptively said.

It is true to say that there is not going to be a shortage of older people in British society in the foreseeable future, and it is true that for many, it's not until they retire that they have the time to devote to botany. So it is entirely possible that the membership of the BSBI, along with the RHS (Royal Horticultural Society), the RSPB (whatever that stands for, Royal Society for the Protection? Preservation? I checked seven pages of their website without finding it - but it's definitely Birds), and other nature-oriented groups, will continue to rise in line with the ageing population.

Going back to the recording issue, a couple of people - although not anyone from the BSBI, interestingly - bothered to ask me why I was no longer a member. The answer is threefold: 1) the BSBI seems to me to be entirely geared around recording; 2) it is only interested in wildflowers, and 3) I found it quite inaccessible for beginners.  Now, firstly, I am just not that interested in recording, so the main thrust of the BSBI does not engage me. Secondly, professionally, my botanical consultancy work involves having to identify plants (including trees, not just pretty flowers!) all year round, not for the brief period in which they are flowering: so the BSBI obsession with flowers does not fit into that aspect of my job.  And thirdly, I am passionately dedicated to helping botany "improvers" to move forward in their IDing,  and I could hardly bear to deal with a group who seemed, to me, to be utterly uninterested in people with only this level of knowledge.  So the BSBI really doesn't offer much to me: I realised that I was barely skimming through the News, and tossing the boring Journal in the recyling bin without even opening it, and it all seemed rather a waste, so I now donate that money to charity instead.

So there you have it: I didn't get a simple answer to the question, but I got some viewpoints, and some new questions, foremost of which has to be  "is it really that bad a thing, if your membership is weighted towards older persons, of whom there are an increasing number?"

Thursday, 10 November 2016

How to use bark as a mulch

Well, you'd've thought this one was quite straightforward, wouldn't you?

It says on the pack, “apply as a decorative mulch to help suppress weeds and retain moisture” so you wouldn't think you could go far wrong, would you?

However, having just returned from a Consultation session with a Client who was extremely dissatisfied with their present barkage (no such word, really!),  I feel it is worth mentioning a couple of minor points that will make using bark mulch just a little bit better, more efficient, less costly, and less of a disappointment.

Firstly, what type of bark to buy? I would recommend micro-bark if you can get it: the smaller the pieces, the less of it you need to use to get a decent coverage, and the better it looks. Really coarse bark always looks untidy: and it's hard to know when you buy it, just exactly what you are going to get, so anything with "microbark" on the pack will be the better quality stuff. If in doubt, look all around the pile of bags of bark - there are usually one or two bags which have been damaged during delivery or storage, so you can often find a sample of the contents lying on the ground.

Second: prepare your ground. This is a big subject, as the way you prepare has a huge effect on the results. Decide beforehand why you want to apply bark: in fact, this ought to be Second, as this decision dictates what preparation you are going to need. So, let's look at that one first - why do you want bark?

Some of the options include to suppress weeds, to look decorative, to protect roots from frost, to preserve moisture, to be an easy-care surface, or any combination of the foregoing.  Before we run through those five, here are some facts which will be referred to as we go.

1) If you want really good weed suppression, you will need to lay a membrane down, over the soil and under the mulch. You might think that any old plastic sheet would do for this purpose, but there is a reason that the garden centres sell so much landscaping fabric: the membrane has to be water-permeable, otherwise you end up with waterlogged mulch and dead (dried out) plants. In my experience, the most expensive membrane will not stop all weeds, and the cheapest will stop most weeds: the cheapest being those yard-square builder bags that lorries deliver sand and gravel in: cutting them up and spreading them out is a bit of a pain, but you can usually get them for free!

2) Birds will flick the bark about all over the place.

3) Bark will slowly rot away to nothing: you will need to top it up, probably every second year.

4) You will need to be generous with it: a skimpy layer of bark looks terrible, especially if you go for membrane, as you will see bald spots poking out through the mulch.

A. To Suppress Weeds.   if you want it simply to suppress weeds, there are a couple of points to be made. Firstly, there are two types of weeds: those that are already in the soil and those which float down as a gentle rain of seeds from above. Mulch will not prevent the latter!

Of there former, there are again two types: those which are already in the soil as seeds, and which need light to germinate. This sort of weed can be successfully controlled by membrane and bark.

On the other hand, we have the sort of weeds that are already growing in the soil: deep-rooted perennial weeds such as dandelion, nettle and bindweed. Unfortunately, no amount of mulch will suppress them, they will just grow right on through it, and even a top quality membrane (see point 1) will struggle to keep them under control. Often, you will find that such weeds will sneakily grow along through the places where the membrane sheets overlap, popping up far from their original roots. They can be dealt with by spot weedkilling: but if you try to pull them up, you will find that you pull up whole sections of the membrane, which ruins the effect and means that you have to rake off all the bark (which is, by now, semi-composted), stretch out the membrane again, peg it down if necessary, then re-spread the bark. This is a lot of faff. If you have perennial weeds, it is far better to get rid of the weeds before you think about laying bark: either a determined weeding session, or a season of constant vigilance with the weedkiller, will be necessary.

And once all that is done, you will still need to be aware of points  2, 3 and 4.  This is where the disappointment comes in: if someone told you that a layer of bark will suppress all your weeds and look lovely for evermore, they are lying!

B. To Look Decorative.  In this case, a light scattering of bark can be made, as long as you appreciate points 2 (birds) and 3 (it will disappear).

C. To Protect roots from frost.  For this, you will need a deep layer, at least a couple of inches, which takes up more bark than you would think... and do bear in mind that many plants, such as roses, trees, anything with a main "trunk", will not flourish if left sitting up to their necks in a deep layer of damp bark - they will rot.

D. To Preserve Moisture: this is a valid use, but you must remember to water the bed very thoroughly before you apply the membrane/mulch, otherwise the mulch will act as a thatch,  preventing water from getting down to the roots of the plants.

E. To be an easy-care surface:  well, I guess bark does fulfil this function, as long as you realise that it is not a wholly weed-free surface. It does make it easier to walk on the beds, if they have a good layer of bark on them: your boots don't get all muddy, but too much foot traffic will compact the bark down into a sort of woodland path effect, which is less good at allowing water through for the benefit of the plants.

So, having decided why you want bark, having bought it, prepared the ground by weeding, weed-killing, and/or laying membrane, now we come to the actual application.

Bark arrives in compressed form, in large bags.

 Here is a typical bag, it just about fills the wheelbarrow, and I can just about lift one of them into it.

Having trundled it round the garden to where I want it, the next job is to cut the bag open.

Don't rip into the middle, as though you were a dinosaur devouring a gazelle (or whatever tender fresh morsels were around 70 million years ago, I'm a Botanist, not a Paleontologist): cut open one end or the other. There are two reasons for this: if you cut the end, you can re-use the strong bag for any number of purposes in the garden - you can turn them inside out to make them plain black, if you don't like the jazzy printing - and because if you rip into the middle, you will just spill it everywhere and waste it. As well as wasting the bag. And I don't like waste.

This - right - is the sign of a GOOD bag of bark. It is so compressed that, even though I've cut the bottom off altogether, the bark is not falling out all over my feet.

It is also dark and moist, this means that, although it makes it heavier to move, the bark is already damp, so it won't "steal" moisture out of the soil. Nor will it create a dry, water-repelling layer, thus depriving plants of the next rain shower. (It also looks much nicer, but that's just an aesthetic consideration.)


 Having opened one end, tip out half of it into the wheelbarrow.

Now fluff it up, by hand: lift it, stir it, break up the lumps, get some air into it. The volume will expand dramatically - this is half a bagful, half of the bag that filled this same wheelbarrow, and you can see that it nearly fills the barrow, even though I've only used half of it.

Fluffing up the bark gives much better coverage: instead of having half a dozen great solid dollops, which crush anything they land on and make the bed look like the surface of the moon, you now have enough to make a good, even coating, without damaging the plants.

Best of all, as you can see in these photos, this bark is not already covered in a layer of white mould. Damp wood chip is a very attractive to fungus, and often you will open a bag to find a lot of white cottony stuff, or long white threads, in some or all of the contents.

Don't panic: it will be one of the many types of fungi that live on rotting wood: no, it's not honey fungus, no, it won't hurt the plants, no, it won't hurt you: it's perfectly natural, the spores are all around us in the soil, in the air, and all that happens is that the fungi help the bark to decompose, thus returning nutrients to the soil. They are, in fact, helping the bark to become composted.

Personally I don't find fungus to be at all attractive, so if a bag of bark does not arrive pre-fungussed, then I am happy! But if it does, no matter, I just fluff up the bark and fling it around anyway.

Now we come to the application: take a double handful of the fluffed-up bark, and throw it along the bed. Don't drop it from above - use a bowling action, and aim to skid the handful sideways onto the surface. This has the dual benefit of making it go a lot further in terms of coverage, and of preventing damage to plants. It often surprises my Clients, if they watch me doing this, that I can "bowl" great handfuls of the bark over perennials without damaging them, and without having to go round every single plant afterwards, shaking the leaves free of a heavy layer of bark.

This fairly small bed took one and half bags of bark to make a good, deep layer: I had prepared the bed by digging a deep gutter all the way around the outside, so that the bark could fill the gutter, rather than spilling over onto the grass.

I know that the birds will still flick some of it about, and it can be a bit of a nuisance when I am edging, but the effect is very nice, and was much admired by the Client.

Job done!

Old techniques for lanky roses

Some time ago, one of my elderly ladies gave me an ancient gardening book, which caused me much amusement: some of the things they used to do in their gardens are, shall we say, out of step with modern life, involving strychnine and arsenic on a regular basis.

But one section caught my interest - the technique of reviving an old rose by tying it down to the ground, in order to promote new growth. Not something I had heard of, and not something I had ever seen done!

This is not the same, by the way,  as pegging down lanky growth, which we do to make domes or fountains of roses: this is specifically for when an old rose gets so hard and woody that it has barely any flowering growth, and where the only real treatment is to dig it up, throw it away, and buy a new one.

How does it work?

It's a simple principle: lay the rose down until it is nearly horizontal, tie it firmly in place, and leave it there until it is forced to put up some new growth.

As luck would have it, last year I was asked by one of my ad hoc Clients about a rose in her garden: it was an old one, had been there for donkey's years, and it only had one upright stem, five feet tall, brown and stout, with a tuft of flowers on the top. Not very satisfactory! I suggested the dig-it-up-and-throw-it-away solution, but the Client said it had sentimental value, and was there anything we could do to keep it?

As I told her, the usual answers are firstly to take cuttings from the newer growth, in order to grow on a new plant, but that can take years to get to a decent size: or to prune the rose hard, in order to promote growth lower down: I've done both of these with success.

But this rose had just one single stem, and if we cut that down to ankle height, well, it would probably give up the ghost and die.

So I suggested that we try this technique, and bless her heart, she was brave enough to give it a go.

When I took hold of the rose,  I found that it was actually quite wobbly, it had done that trick where they seem to rise up out of the soil,  so it looked like a good risk to take.

The actual bending was quite nerve-wracking: what if I broke the stem? What if it split?  To my relief, it went straight down like a slow-motion skittle:

 ... so I tied it to a handy stump to keep it in place.

I didn't prune off any of the top growth, I just left it there, lying on the ground.

 Here's the close-up of the base of the stem, showing that there is just one stem, and it is now bent right over.





Last week I was back in that garden again, nearly a year to the day later, and look!

 Lo! and behold, the rose had put up two lovely strong new shoots, one from right down at the base (“perfect!”), the second one from about a foot further along the stem.

Not the best of photos, but I hope you can see it: the first stem is on the far left, right where the brown arching stem leaves the ground.

The other is a little to the right, and both of them are strong, stout, and shooting straight upwards.

They had each flowered nicely, at about 4' off the ground: had I been there through the summer, I would have dead-headed them both very hard, probably back down to knee height: I might even have bent the two of them over and tied them in to the original stem, to get them to produce more new shoots.

Interestingly, the "old" growth did nothing: no flowers, no new shoots, all the energy went into these two new stems.

Here's a closer view of the two new stems: quite impressive!

As it's well into autumn now, I have left the old stem tied down for one more winter, and have instructed the Client to cut it off early next spring, as close as possible to the new shoots, which should also, at that time, be cut down to about knee height.

I have also suggested that they cut back the Thuja hedge a bit more forcefully, to give the rose some more room - and to water the rose well in spring, to promote new growth.

If it were mine, I would probably keep just the far left-hand shoot, the one nearest to the root of the plant, on the grounds that it will make a more natural-looking new bush: although it is possible that when the original shoot is cut off, the stump might well "spring" upright, which would actually be a good thing. The second shoot will quickly straighten itself out - at first, it will appear to be growing at a very odd angle! - and the rose will then be well on the way to creating a good new structure for itself, with branching much lower down than before.

Hopefully, next year there will be more strong new shoots, and this rose will be revived: so there you go, an interesting old technique which certainly does appear to work!