Promoting strong early growth?

Most people call Leylandii fast growing but as anyone who has planted a fresh row of trees hoping for dense and instant privacy to 6-8ft knows they dont quite grow quite as fast as one would like.

This frustration has not been relieved by any knowledgeable contribution across the internet which leads me to this post.

My situation. We have a garden and a long established (probably 15 years at the least) monster of a Leylandii hedge along the back fence. These are the neighbour-behind's trees which we quite like. They are a job to trim though as they are 12ft our side and nearer 15ft his side where the ground falls. But a solid square hedge. An area of disused garden to the side was on our minds to bring into the main garden. But in order to have some privacy from houses across the road looking out of their bedrooms windows, we proposed to grow a similar hedge and forma complete L shape, maybe not as high as the other rear hedge but a good 10ft.

In the Autumn of 2007 we had a run of leylanddi (standard green)planted. They were 5 footers (against some advice who suggested smaller plants were going to grow quicker in the long run). I can be a bit obstinate and was determined with good care I could beat the younger plants timeframe.

The plants are now a good 10 feet to the lead tip. Am I right they would be best grow a lot higher before cutting the tip off so some density is given to the top of the hedge? As a result of this good height growth sideways filling has been pretty poor. There is certainly no privacy afforded yet. We would like to keep the hedge fairly narrow say 4ft max, so ia have been avidly clipping back any sideways growth beyond this point.

My big question is this. Has anyone done a study on growth patters in young leylandii branches while still green. Whenever you seem to cut back strongly new growth on established trees, the trees seem to grow back with even more aggression. This could be down to the fact that the earlier growth has created a stronger lead branch stem from which to resprout, and maybe the root system had grown proportionally stronger from the extra foliage (since cut) to feed faster future growth. My main idea was to be lazy this coming season and not trim the trees at all until Spring 2011, then cut back strongly into all this growth, for the tree to refill during 2011. Do you think this will fill the tree faster than a simple constant trimming twice or thrice a year?

I have also been feeding the trees with chicken manure pellets, bonfire ash, crushed eggshells and grass clippings. Last year was so wet we didnt need to water during the Summer - but we will during dry spells.

Its worth mentioning that the new hedge is growing under the umbrellas of two fully grown Laburnum trees, which compete for nutrients and the worst growth has been at the end where it meets the 15ft established hedge, being so bereft of nutrients and light. Still the little Leylandii are fighting hard!! Come on babies!

Any comments welcomed from tree specialists.

Re: Promoting strong early growth?

Hi Mate,

You are indeed right in the fact that Leylandii's do suffer from reduced growth when in the shadow of larger trees. We have a few that probably have lost 50% of their growth because they are in the shade.

The best thing to do like you say is give them feed and bonfire ash is pretty good (plenty of carbon in there.) If people do feed them then they can do without as much light and get their nutrients a different way. This can help a lot when getting these things started. Of course as they are tall enough to start to obtain sunlight direct, they won't require feeding from then.

With the bushing out if you cut the tops of, I'm not aware of any real reasearch into it but it my guess is it is more an optical illusion.

As the tree doesn't grow in height it makes it appear more fuller at the existing level, this would be fuller anyway as the tree would have grown.

However it's just my guess rather than anything scienetific so would be good to know if anyone has done any research into it.

Cheers
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