Summer is upon us…. hooray!

Summer is here

Summer is here

But how does this affect your trees?

Pruning

Deciduous trees have been putting on all those leaves, and that takes an effort – or to put it a little more scientifically, it is a serious commitment of energy, with stored carbohydrate being devoted to the production of new leaves. In time of course those leaves put that money back into the bank as they produce sugars via the magic of photosynthesis, but initially there is a drain on resources. So, it follows that pruning all that young growth off is a double whammy – it deletes the soon-to-be generated sugars, and the tree has to further deplete its reserves in order to produce a second flush of new growth. So – not the best time to prune severely!

Conifers on the other hand do not have to put on a whole new suit of clothes every spring. In fact trimming in the winter (you might think this is a ‘dormant’ time) can stress an evergreen as it really doesn’t want to think about generating new growth when it’s cold (can you blame it). So – spring and early summer can be a good time for pruning or trimming conifers and other evergreens. However this should not be done when it is very hot and the sun strong, as the newly-exposed foliage can be scorched. This can happen with Box for example, with the leaves bleaching as a consequence. We had this happen, and got the blame, after a very wealthy client insisted on ornamental Box hedging being trimmed during hot weather in June.

If you have a Leylandii hedge (and who doesn’t) then don’t mistake Aphid damage for drought symptoms. Aphid damage normally occurs on the side of tightly trimmed hedges, either green or golden. Patches of brown appear, and unfortunately by that stage there is little prospect of the affected area recovering, as they are probably stone dead – but it is important to try and limit the spread and save what is still green.

Of course there is a transition from fresh green to pure brown, so you may be able to spot a dulling/yellowing initially. The aphids themselves are elusive – I have only ever seen them a couple of times, despite their being quite large. The good news is that our spraying regime can be very effective in halting the spread, though it may need doing annually. Phone the office and ask to speak to Nick if you want to talk it through.

Quite early Cypress aphid damage on golden Leylandii (‘Castlewellan’)

Quite early Cypress aphid damage on golden Leylandii (‘Castlewellan’)

Hedge trimming

Now that the frosty weather is past, we have a major work load of hedge trimming more or less right through until late autumn. Some people like the trimming done in spring or early summer, to get a good effect while the garden is in regular use, and others like to end the season with a good trim, before the risk of frosts starting again.

An example of the latter is the famous Yew collection at Painswick churchyard which we have been trimming for perhaps 25 years now, always in September in good time for their ‘clipping’ ceremony (which despite the name does not involve trimming the trees!) Don’t forget to look after your hedges – it is a false economy to skip it, as the twigs rapidly thicken to the point where a hedge trimmer can’t do the job – meaning much more expensive work using saw and secateurs – or an ever-widening hedge.

Regular trimming is the key and that usually means annual – nearly all evergreen hedges will only tolerate very limited cutting back, so it really pays off to keep them narrow, otherwise the job gets more and more time consuming to trim as they get wider and wider.

View from the Painswick Yews

View from the Painswick Yews

Work in progress, September 2010! Lots more on the ‘Seasonal Blog‘ pages.

High hedge trimming

High hedge trimming

Over the years we have developed an unusual method of trimming the top of this massive Leylandii hedge… Steve claims to really like this work!

New plantings

Have you planted any new trees in the last winter season? We seem to be having extended dry periods in the spring, and this can be a real strain on new plants, as their body clock is forcing them to produce new leaves and shoots, yet their root systems have not yet extended out into the surroundings, so unless moisture is readily available they may be in trouble. So, don’t think that because they are safely in the ground you have done your job – water those plants when the soil is dry and if there is no rain for more than a few days. A good soak is best but see the word of warning below about overwatering!

This sad picture of young Oak was taken at Kew Gardens after a really dry spring; I’m guessing they were planted at more or less this size, but could be wrong:

Drought deaths Kew

Drought deaths Kew

Mulch

We all know mulch is fab (keeps moisture in, keeps weeds out) however make sure organic mulches such as woodchip or bark are deep enough – 75mm / 3” would do nicely. Too thin is a false economy – it won’t do the job properly. For individual trees, a good sized ring at least 1m across is needed; make sure you remove deep-rooted weeds first. Fresh woodchip can take some nitrogen out of the ground as it starts to break down, so it is best used composted (leave in a stack for at least 2 – 3 months prior to use).

Mulching, Aussie style

Mulching, Aussie style

This picture shows some serious mulching in Victoria State, Australia – note the edging strip to stop spillage onto the grass. That is Alex Bicknell in the picture, my old college friend. He has a thriving business over there and took Frankie and me on a great road trip a few years ago (including a spectacular big-tree climb – see my blog ‘Geoff climbs tree shock‘).

Overwatering

Believe me, this is easily done especially if your soil is not free draining and you are using mulch. The planting pit can hold water like a bucket and, with the mulch dried out on the surface you may not suspect a thing until the leaves look small and miserable, maybe browned at the edges – yes, all the symptoms of drought!

The danger then is that even more water is added. The roots are dying from waterlogging – they need air to metabolise, like all living things (unless specially adapted like a few species). So always check under the mulch, digging down a little way with a trowel.

If waterlogging has been going on for a while then roots may be black, dead and the soil dark and smelly (anaerobic). So: if still nice and moist – do not add more water.

For bulk supplies of composted woodchip mulch delivered to your address – phone the office. You’ll find it ludicrously cheap compared to buying bags at the garden centre!

Finally, I was lucky enough to visit Cuba recently. Although not strictly a tree-spotting holiday, Frankie and I travelled right through the island with a small group so there was plenty of interest.

Trinidad, Cuba, April 2011

Trinidad, Cuba, April 2011

I take it you are just looking at the Palm trees!

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