Hornbeam hedge - disappointingly few leaves retained

[kGarden]

I've been meaning to ask your advice on this for some time.

It seems to me that our Hornbeam hedges (now about 5 years old) have disappointingly few leaves retained this winter. I would say that 10% of the plants have lost all their leaves, and many of the others are "patchy".

I wonder if they perform better in an Autumn which turns cold suddenly? as last Autumn was mild continuously. I don't remember any strong winds in the Autumn that might have dislodged the leaves. We don't have much in the way of Beech heading here, or nearby, (the heavy clay is not suitable) but I would say (very subjectively) that they have held fewer leaves than in other Winters too.

Perhaps a factor of last Summer, rather than the Autumn / Winter ?

[charlie]

Afraid I have no experience of either, nothing on the web?

[JohnJearrard]

Funny you should mention it - I was looking at a friends hornbeam hedge last week that was bare. Can't offer any sensible reason, it is well sheltered.
I'm sure you know but Beech and Hornbeam (and Oak, but I've never seen a hedge) retain their leaves while they are juvenile and shed them once they become adult. Hedges that are regularly clipped remain in juvenile growth and so keep their leaves. Maybe a long wet winter has left them feeling old - it certainly has me!

[kGarden]

I read a forum discussion some years ago about someone who had bought an "instant hedge" of Hornbeam, or maybe Beech, and was complaining that he had paid a fortune! and it was not keeping its leaves. The discussion came to the conclusion that the individual plants that made up the hedge were "big" - planted perhaps a metre apart - and as such had probably switched to "mature" and thus were not holding their leaves.

Mine are, hopefully, still juvenile. Not all that old, but they have had all branches "pinched" from year one, so I don't think they can have got it into their heads that they are Mature, but I'm not sure what the exact trigger is. Perhaps as the hedge thickens up (it had its first proper face-clip for the bottom 3 or 4 feet this year, so the top part is still straggly) it will behave better.

Only think I can think of is that I have let it grow "tall" to then top it and let it grow back. I think the norm is to let it get to a foot or so above final height, cut it back to 6" below, and then establish a top-surface at the desired height. I topped mine (for first time) this year at 8' and quite a few plants were a good 3' taller than that (albeit not much substance to the bit I cut off). That said, most were a foot taller, if that.

Dunno if any of that suggests anything that I could have done differently . better, or that I should now start to do?

I'll try to remember to report back next winter to see if there is any difference, given a different season's weather influence etc.

I didn't think to Google it before asking, sorry ... but I'm not sure what Keywords to use. I'll have a bash and see if I turn anything up.

[kGarden]

Well that jaunt found the original thread I remembered :)

http://landscapejuicenetwork.com/forum/ ... -retention

There is talk there about making sure that the hedge is trimmed early enough (i.e. in Summer, and perhaps again in Autumn) to trigger new shoots before Winter, and it is those (juvenile) shoots what will hold their leaves. I get the definition of Juvenile now ...

Probably the plants that have lost their leaves have not had any trimming at all, as they are "small enough", within the overall size of the hedge, not have reached the extremities, and therefore not to have been snipped by the hedge trimmer at all.

Next year should ensure that pretty much all the face is wide enough to get snipped, and I will be sure to do it early enough to trigger new growth before autumn.

[JohnJearrard]

"juvenile" is a poorly defined term when applied to trees, but it is a physiological state of the plant, not simply the age of the twig. With forest trees it generally related to the period when they are growing rapidly beneath an established tree canopy. They tend to produce upright growth with few branches, large leaves and long internodes. Once they reach the sunlight the branches thicken, internodes shorten, leaves are usually smaller, they produce horizontal branches and start to flower. I'm not aware of any research that has identified clear triggers for the change but exposure to full light clearly has an effect. However plants grown as hedges in full sun remain juvenile as long as they are trimmed. Pot bound plants may be pushed into premature adulthood in the same way that pot bound plants are often reported to flower more freely. Possibly an expensive hedge of large potted plants had already become mature by the time they were planted.
The key point is to trim them regularly. With hornbeam I like to trim once the spring flush of growth has started to firm up (maybe June) and then tidy up any straggling shoots in September.
And congratulations on planting a Hornbeam hedge, they are lovely things and it's the county tree of Essex (I'm an Essex-boy)!

[kGarden]

Thanks John, very informative.

I enjoyed this article about Hornbeam, in particular, by Monty Don on my Google travels looking for answers.

http://www.theguardian.com/lifeandstyle ... 14/gardens

Het Loo is on my must-visit list, as I would like to create a tunnel-walkway and could do with stealing some ideas from the Queen's Garden at Het Loo; I've collected some pictures in a PInterest folder

https://uk.pinterest.com/kgardenpins/paleis-het-loo/

[kGarden]

Diligently clipped the hedge last Summer. Its still young, but there is a reasonable amount of "cover" on it this winter. The top 18", which is all "first year growth", is just twigs - looks like one of those two-tone hairstyles that youngsters get! I plan to get the cutting-platform out over the winter and "nip" all the branch-lets with secateurs to promote a good branching structure. There are quite a few lengthy branches that have grown sideways within the hedge, and really long, which I think would be better "pruned" to force a tight structure.

But ... I remain disappointed that a Deciduous hedge is "not all that dense" in winter. Of course this was obvious to me, so we are only really taking about the matter of "degree".

The thing that set me on this train of thought was seeing Monty Don's garden in the Spring episodes of Gardener's World, where it was possible to see from one end to the other through the skeletons of his hedges (Hornbeam I think, might be Beech) as they disrobed completely in the move from Winter into Spring in readiness for the clothing of their new leaves.

So I have a plan. Where I don't want the hedge to be transparent, at any time, I am going to plant something evergreen behind it. Mostly my Hornbeam hedges partition the garden, deliberately blocking the natural / direct view, so reinforcing that with some evergreen shrubs will mean I have the benefit of the Hornbeam / Beech informal style of winter-leaf cladding, and not the far more formal look of Yew (which I do have in places, where I want that look, but I also want a contrast in the less formal places).

Apologies if this is obvious to everyone else, its only just dawned on me!

[charlie]

Hedges are so important to a garden I am surprised that they are not often considered worthy of discussion on some garden groups, its difficult to see how you could grow anything without their help in open situations. there are so many different plants you can use. I have been following this thread because I have never (knowingly) come across a Hornbeam hedge, Beech yes but Hornbeams only as trees.

This does not mean I enjoy cutting them! :)

[kGarden]

Thanks Charlie

Hedges are so important to a garden I am surprised that they are not often considered worthy of discussion on some garden groups

I don't think I've ever seen the discussion in print that Beech / Hornbeam are very bare when setting their new leaves (and its not a day or two! or course, more like a month). Its a piece of knowledge that I could have done with.

Cristo Lloyd wrote some useful stuff about hedges, but that was mostly drainage recommendations and not planting anything like as close together as the plant-sellers suggest! as a mature plant will, then, have so little ground to get its nutrition from. One of the mega-Yew-hedge stately homes was planted at 2' centres and then a few years later every-other-one-removed - although they do say that when the time comes to cut it back to the trunk, because annual clipping has allowed it to become too wide, over time, the recovery-time is, of course, longer than if planted with closer-centres

difficult to see how you could grow anything without their help in open situations

Yes, good point. For us (given that it is flat around here) it was to create "rooms", but of course "flat" also means "exposed". We started out with the notion of having some vistas across the surrounding countryside, but we have no borrow-view opportunities, and although the view is not exactly flat, it is not really undulating enough to create interest.

I have never (knowingly) come across a Hornbeam hedge, Beech yes but Hornbeams only as trees.

We don't see many Beech hedges around here, they don't do well on our heavy clay soil. I suspect that's the issue, pure and simple. I have a Copper Beech hedge, hard to get that colour in Hornbeam Natch!, and that has replacement soil, good drainage and raised quite a bit, and still I had losses and have poor growth in some places along it.

I presume once a young Beech struggles to tree-status it then drains enough water that it can cope, but even so we don't see many/any? stands of Beech round here, there are specimens in gardens, but that's about it. Drive a bit further away, to lighter land, and then woodland is full of them