It's July… So Why Are the Leaves Falling Off My Trees? It's Not What You Think!

Walk through almost any Surrey, Hampshire or Sussex outdoor space this July, and you'll notice something splendidly peculiar.

Leaves. "To the South West... thousands of 'em."

Also probably every other compass direction as well, but any excuse to shoehorn in a quote from one of the greatest films ever made.

For a moment you wonder, after all the World Cup excitement, if you've somehow slept through August, September and October and woken up in autumn.

Depending on what nefarious escapades you have embarked upon, or indeed when you are reading this...

The good news is that you probably haven't.

The trees have almost certainly not decided to skip summer either.

Trees are cleverer than they look.

Unlike us, they don't complain when they're thirsty. They don't post dramatic messages on social media announcing they're "literally dying." Instead, they quietly start making sensible financial decisions. (Yes Mother, I am trying to take note.)

Think of every leaf as a tiny factory. It manufactures food using sunlight, carbon dioxide and water. The downside is that every factory has running costs.

Every leaf slowly loses water throughout the day through thousands of microscopic pores. When the ground becomes dry, the tree has a problem.

It can either keep every leaf and continue losing precious water... or it can go all Alan Sugar. Most trees choose to offer involuntary redundancy. The oldest leaves, shaded inner leaves and those that aren't earning their keep are quietly cut loose. The tree seals them off and lets gravity do the rest.

Of course, the tree isn't consciously sitting there with a calculator and a spreadsheet. It doesn't know what The Apprentice is. Millions of years of evolution have simply arrived at exactly the same conclusion that any sensible manager eventually would.

It isn't panic. And despite what many would have you believe, it isn't stress.

It's budgeting.

Is the tree dying?

Usually not.

A healthy oak, beech, lime or sycamore can shed quite a surprising number of leaves during a hot, dry summer and still be perfectly healthy.

Think of it as switching the central heating off because you've received a frightening electricity bill.

Mind you, if you're still using the tumble dryer during a July heatwave, perhaps dropping it from a great height would be more economical.

The house is still standing.

You've just become a little more fiscally responsible.

However...

If leaves are turning black, branches are dying back rapidly, the bark is splitting or the entire canopy suddenly goes brown, then that's a different matter altogether and worth investigating.

Should I water it?

That depends on its age.

A mature tree that's been happily growing for twenty or thirty years generally doesn't need your help. Its roots may stretch many metres beyond the canopy and surprisingly deep into the soil.

Think of a mature tree as someone who has spent decades quietly building up reserves. When difficult times arrive, it has something in the bank.

A newly planted tree is rather different. It hasn't had time to build those reserves. Its roots are still shallow and close to where it was planted. During prolonged dry weather it may need a deep soak every week or two rather than a daily sprinkle.

It's rather like someone who has just discovered contactless payment and is suddenly wondering where all their money went.

Will those missing leaves grow back?

No.

Once a deciduous tree has shed a leaf in summer, that's usually it for the year.

The Lady was not for turning, and neither is the tree. It has already made its decision. Those leaves won't be returning this year—or ever.

The tree simply carries on with a slightly smaller workforce until autumn.

So... will they all fall off again in November?

Yes.

This is the part that seems gloriously unfair.

The tree has only just finished dropping a few leaves to save water... then, a couple of months later, calmly and almost vindictively drops the rest.

It's almost as though it waits until you've finished clearing up before thinking: "Actually... I've found a whole lot more. Have that, sucker!"

Nature isn't wasting leaves. Most of the useful nutrients have already been reclaimed. Think of it as taking the batteries out of the TV remote before throwing it away.

What it sheds will eventually return to the soil in some form or other.

The tree is simply recycling its resources.

Can anything be done?

Actually, yes.

It's mulching. There I go again with my great horticultural love. The panacea for almost every gardening ill. I promise this will only take a moment...

As I frequently repeat, a generous layer of organic mulch helps keep moisture in the soil, reduces temperature extremes and gradually improves soil structure as it breaks down.

It is the simplest, most important job with the biggest long-term benefits. If you do nothing else, mulch.

Good soil is like money in the bank. You may not notice it immediately, but you'll be very grateful when difficult times arrive. OK, that's enough.

Trees don't usually die from one hot summer. They decline after several difficult summers in a row, each one quietly chipping away at their reserves.

As our summers become longer, hotter and drier, July leaf fall is likely to become a more familiar sight. Looking after the soil beneath our trees is becoming just as important as caring for the branches above them.

The bottom line

If your lawn is collecting leaves in July, don't panic.

Your tree is probably doing exactly what millions of years of evolution taught it to do.

It's managing its resources, reducing water loss and giving itself the best chance of surviving until the rain finally returns.

Rather sensible, really.