Garden School:

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

Wednesday, 27 July 2016

How to: Cut back Primroses in summer

A simple task, but a surprising number of people are unsure how to deal with their spring flowered primroses now that we are in mid-summer (says she, with wry face, looking at the rain streaming down the window pane).

The answer is simply to chop them right back!

Here is a typical small group of Primrose plants:

 the leaves are yellowed, limp and floppy, and they look rather a mess.

If you get down on hands and knees and look closely, though, you will see that new, fresh green leaves are already starting to push through, but of course they are completely covered by the wilting foliage,

So, what to do?

The procedure is remarkably similar to that in my earlier article about Cutting Back Aquilegia: you can either spend a lot of time carefully snipping off the dead leaves individually, or you can take hold of the entire clump and sever them at just an inch or so above ground level.

Here's one I did earlier, as they say: more accurately, here is the same clump two minutes later.

The actual process is to ruffle through the foliage to work out where each plant is, then round up all the leaves in one hand, pulling them upright: then with the other hand, swoop across with the secateurs and chop the lot.

Yes, there is a risk that you will chop off a couple of quite nice new leaves, but they will soon regrow, especially if you water the plants afterwards : even if it looks like rain, a good drenching will help them get growing, and many primroses are growing in quite shaded locations: this little group are sheltered by a dry-stone wall, and are underneath a plum tree, so they won't get much "natural" watering unless it really pours.

Having chopped off the leaves, I then use my faithful Daisy Grubber to gently rake through the stumps to pull out any dead matter,  then to fluff up the earth around the plants (which breaks any surface pan, allowing your watering to have the best effect instead of running off and into the lawn) and tidy up the newly-revealed edge of the grass.

It all takes just a couple of minutes, but the result is quite impressive: and in a week or two, when the new leaves spring up, it will look great!

Saturday, 23 July 2016

Unusual Sedum fertiliser.

I was asked to move a gigantic clump of Sedum last week, as the builders are due in soon to widen the path, so even though it is entirely the wrong time of year, it was either move it, or lose it.

As usual, when you try to lift a well established clump, they fall apart into several sections, but that's fine, as I was planning to split it up anyway: if you try to move a tall Sedum at this time of year they invariably flop, droop and snap (which sounds like a rather unappealing new breakfast cereal) so it is usually best to split them, cut them down, and just accept that you are going to miss out on flowering for this year.

I was particularly keen to lift and split this clump, as it was infested with couch grass, which had been resisting my attempts to weed it for the last year or more, so this was my chance to get rid of the unwanted infiltrator for once and for all.

In went the fork, out came the clump, falling easily into two main sections.

Oh, hullo, what's that?

Let's look a little closer:

Is it a bird? (It's certainly not a plane, although did I find a small plastic helicopter in my garden at home the other day, presumably a small child was crying somewhere for the loss of their toy)

Yes, there was a complete, dead, bird right in the densest part of the plant. Feathers, skull and all, but no contents: presumably they had rotted away and done their bit to promote this year's strong, healthy growth.

Well, I'm familiar with feeding plants with fish, blood and bone, so I suppose that dropping a dead bird in the middle of the plant is no more than nature's way to provide two out of three of those organic fertilisers? 

Friday, 22 July 2016

Sad looking Willow: Salix kilmarnock

 Mike recently sent me photos of his "sad looking Willow Kilmarnock" and asked if I could advise what the problem was, and would it recover.

It's incredibly hard to diagnose from photos - it's not always easy to ID things, either! - but there are a couple of quite straightforward issues with this tree, so I'll say what I think, and you can all do your own research if you think I am wrong.

There seemed to be three main problems: orange spots, curling leaves, and skeletonised leaves.

Firstly, here are the pictures:

 This one shows the orange spots on the leaves.

Orange spots = a disease called rust: it is caused by a fungus, and is often specific to the plant, by which I mean that plums get plum rust, willows get willow rust etc.

Rust does not usually kill a tree, but it reduces the vigour - as the leaves have less green surface area available for photosynthesis - and it looks pretty horrible, so it is not something we want to encourage.

Treatment: if there are only a few leaves involved, pick them off as soon as you see them. This can help to slow down an even halt the infestation.  If there are a lot, then removing the leaves can do more harm than good, so just leave them in place.

Clear up all fallen leaves as they fall - either burn them (which is preferable) or send them off to the council recycling in your wheelie bins: don't compost them, whatever you do. Commercial composting reaches much higher temperatures than our home composting does, which can kill the spores, but if you put them in your home compost bins then you are likely to end up with compost which is full of rust spores. Not good.

Prevention: spray with a fungicide. Pick one that includes the word "rust" on the pack: I won't give you the technical names of the chemicals involved, as they keep changing, but if you pick one which is good for "rust" you should be ok.

At the end of the season, make sure to clear up every single fallen leaf, diseased or not, and at the same time, check the tree for any dead or diseased-looking parts. Prune any such off with sharp secateurs, and burn or dispose of all this material: don't make leaf mold from them, just in case.

Next is the curling leaf edges - this is usually caused by aphids: they suck the sap and distort the leaves. It can occasionally be a virus, but that would be carried by aphids, so the treatment is the same. To prevent aphids, you need to spray with a Bug fighter: again, I won't give chemical names, just pick a spray with a picture of an aphid on the pack, it's entirely up to you if you go full-on chemical, or try the "organic" fatty acids ones.

Again, aphid damage won't kill a tree - usually - but it looks quite unpleasant. If some leaves are so distorted that they are completely crumpled up, pick them off, but otherwise just leave them.

Thirdly, the skeletonised leaves: these are simply being eaten by caterpillars/beetles. Once again, pick off any leaves that have been totally destroyed, like the one in this picture, as they are not doing any good at all.

The treatment for this is again, a bug spray, but you can help the tree by checking all the leaves on the tree (remembering to look underneath the leaves as well as on top) and picking off any caterpillars that you find. I would squish them, but I suppose it's ok to fling them away into a far corner of the garden... and keep on checking, as they do tend to keep on coming.

The fact that this tree has healthy new buds is a really good sign: all of the above problems are, in effect, only cosmetic, but of course we want ornamental plants in pots for their appearance, don't we!

So, what regime would I suggest?

Firstly, get the hose out and "gently sandblast" the tree, if you see what I mean. Wash all the remaining leaves, both the top and bottom surfaces, to literally wash off aphids and anyone else living there. As you run the water over them, use your fingers to gently massage each leaf, ensuring the water gets into all the nooks and crannies. This should remove the majority of the current population, giving the tree a short breathing space in which to recover, before the little buggers (that is a technical term) move back in.

When it's dry, and you have removed any really damaged leaves (into the bin or onto the bonfire heap, remember?) spray it with any of the fungus fighters and the bug fighters: Bayer do a very good one which treats both. (No, I'm not being paid by Bayer!)

Most of these treatments are "systemic" which means you spray it on, the plant absorbs it, and when the critters come back and start to eat the tissue, they absorb the poison, and die. So, once you have sprayed the tree and the chemicals have infiltrated it, it is protected from future attacks. But not for ever! Read the pack and check when you should re-apply it. And make a note that, next year, you will apply it earlier in the year, before the problem starts...

Meanwhile, you can help the tree to be healthy enough to resist attack, Here is the overall tree:

Pretty little thing, isn't it? You can see why these kilmarnock are so popular.

Now, Mike (the worried owner), I hate to sound critical, but the pot is just a little bit small for that size of tree, so if you can repot to a bigger one, so much the better. Choose a straight-sided pot if you can, rather than a tapered one: it's more stable, and gives a larger volume of soil for the tree to enjoy.

Give it a balanced feed (something like Growmore, it doesn't matter if it is pellet or liquid) and ensure it's well watered for the next few weeks, but at the same time you don't want it waterlogged, so raise the pot up off the patio on "feet" to allow better drainage.

This four-star pampering should help the tree to produce a new flush of leaves, and by spraying it now, those leaves should be much more resistant to damage by rust, aphids and caterpillars.

Hopefully, this will sort out the problems!

Saturday, 16 July 2016

Hedges: how to recover an overgrown one

I get some interesting challenges in my daily work - and two years ago I was presented with this one - a very overgrown Lonicera Nitida hedge.

It's a small panel of hedging, marking the edge of a property, providing some privacy, and giving some shelter to cars parked in front of the garage.

But it had been allowed to get a bit out of hand, to the point where the garage door wouldn't open anymore! It had grown outwards into a V-shape, with the top being more than twice as wide as the base. This is bad for many reasons, quite apart from looking ridiculous: it is very hard to trim a hedge that leans towards you;  the top overshadows the base so the base often loses leaves and becomes bare and brown, which is ugly; it flops around on windy days, swaying alarmingly and threatening to fall over; and a wide-topped hedge is constantly at risk of splitting open and flopping outwards in heavy rain, or snow. Plus, the garage door wouldn't open any more! As a lesser problem, the neighbours were also complaining that the outside edge was grabbing at their cars as they drove down the lane.... so it was time to do something.

I ran the hedgetrimmer over it as a first fix, pushing back into the hedge as hard as the hedgetrimmer would go, just to see what general shape it was, and yes, it was clearly twice as wide at the top as at the base.

The next job was to trim it back close to the building so the door would open: that was easy enough, I just took the loppers and chopped away a section of it: easy to do, but not a permanent solution, as the hedge now had a big bite out of it, which was not pretty.

So, the main job is to restore it to being a neat, upright, slender hedge. This is a big job and will take the best part of three years, as it has to be done in stages. Doing it all at once would probably kill the hedge, not to mention leaving the Clients looking at a hideous brown stump for months on end.

Year One: cut back just one side of the hedge. This is done with loppers - the hedgetrimmer simply can't get through the thickness of the stems. I do this sort of thing by eye, but if you are not confident of your straight-line abilities, put a peg into the ground and stretch a line to mark where you want to go. I wanted to go back to about a foot and a half inside the boundary of the property, which allows it a bit of growing room between clippings.

Typically, I didn't take any photos of the "before" stage, so I can only show you what it looked like from half way through the exercise, but you will be able to see from Part II what Part I was like. I did this in mid summer - not the best time to do it, I prefer to do this work in spring, so that the bare branches will "green up" as quickly as possible, but the Client really wanted to use their garage again!

By the following May, here is the result:

 You can see that the outside face is nicely upright, but the inside is still leaning in towards the drive.

Just imagine what it looked like when it was leaning out in both directions!

After six months, the outside had "greened up" enough to need a light pass with the hedgetrimmer.
 A month later, and you can see that the whole hedge is growing nicely, so it was time to tackle the inside face.

Year Two: cut back the second face.

First job - run the hedgetrimmer over the outside face and the top, so I can see what I am working with.

Next job: repeat what I did to the outside.

There you go - scary, isn't it?!

I have started at the front, and used loppers to cut into the hedge at least a foot or more inside it's current edge.

The whole side of the hedge - matted together and impenetrable - is falling away, like shearing a sheep but much, much slower.

I just kept cutting until I met the "step" where I'd cut in to allow the garage door to open. Obviously, when doing this, try to keep the cutting line parallel to the other face of the hedge, and try to keep it vertical. It's not easy!

Here's the result after the first pass - nearly enough to fill the yard square builders' bag,  and a horrible brown hedge, all scruffy and ugly.

The message at this point, should you wish to try this yourselves, is "Don't Panic."

I went over the hedge carefully by hand, pulling out any branches which had been severed, but which were still caught up in the "live" part. This is because they will die and go brown, making it look as though you have killed the hedge, so it's worth taking the time to pull them all out, even though it leaves behind a thin, sometimes slightly holey, hedge.

 After running the hedgetrimmer over what was left, you can see that now I have a neat slender hedge, tapering inwards slightly at the top, and running pretty much parallel to the road, and pretty much parallel to the edge of the garage door.

The angles are slightly deceptive, the inside face is actually a good six inches clear of the garage door edge, in order to allow the hedge room to grow in between clippings.

From this angle, you can see more clearly the gap between hedge edge and garage door edge, and you can see quite clearly that it is almost entirely brown and bare.

However, it will soon "green up", and the reason for doing the outside face first is to reassure the Client that it will work! They don't have to look at the outside every day, but they do see the inside face, so it makes sense to do the least visible face first, give the hedge time to recover, and then tackle the side which is seen every day.

This took place last month, and already the bare hedge is starting to sprout.

Stage Three is to reduce the height, I'll be doing that next spring: the garage has a house number on it, which is currently completely invisible, and I aim to get that sign clear of the hedge again. This also means that the hedge will be a great deal easier to cut, as I won't need to stand on the steps to reach the top of it.

As always with gardening, there are a couple of extra things which need to be done: when you cut back a hedge really hard, you need to give it a feed at the time, and I like to keep a hard-cut hedge well watered for the first couple of months, to give it the best chance possible. And it is always a good idea to rake out as much dead material from inside and underneath the hedge as you can: a really vicious chop can give you the chance to clear the base of ivy, weeds and general rubbish, which reduces competition, allows the free flow of air (important to prevent disease) and greatly enhances the appearance of a hedge.

So, to summarise:

Year One: cut deeply into one face only. Remove all cut branches, shake out and rake out all dead leaves and debris from inside the hedge, clear the base, feed and water.

Year Two: repeat for the other face. Don't forget to feed it, and to water it for a few weeks afterwards.

Year Three: lower the overall height, as much as required.

The top can actually be done at the same time as one of the faces, if you want to get it over and done with - the main reasons for doing it as a third phase are to leave the hedge plenty of green leaves for photosynthesising while it is recovering from each of the major cuts, and to leave the the Client as much greenery as possible for as long as possible. Once both sides are green again, it is much less noticeable if the top is cut off - and the tops of hedges always recover much faster than the sides.

And yes, this technique is used for pretty much all sorts of hedges: evergreen, deciduous, and even flowering hedging such as Escallonia.

So be brave! If your hedge has grown out of control, get on top of it! And just to prove that it doesn't kill the hedge, here is a photo of the scalped edge of the hedge one month later, now sprouting green:

It's not pretty, but it's alive!

Oh, and look, there's the house number, to show how low the hedge used to be.

Good, healthy new growth...

... from most of the cut points.

I'll give it another month or so, then any branches or cut ends which haven't produced new growth will be cut out, which will reduce the general brown-ness.

This is the one advantage of Lonicera Nitida hedging - they do recover quickly from a big chop!