Be careful when planting trees in your garden

When designing a new garden, trees really should be the first feature to be considered, but great care must be taken as some have damaging root systems and should be avoided in small gardens, says Peter Dowdall.

Trees are natures carbon mops, filtering out many of the pollutants in our air and creating a fresher, more enjoyable environment. 

In any garden much thought should be given to the choice of tree — and the smaller the garden the more important this becomes.

A tree is going to be a commanding feature and if the garden is small, then it willquickly outgrow its space, crowding out theplot and taking it over. 

When designing a new garden, trees really should be the first feature to be considered — from where are they to be planted, to which variety to choose, and how tall and wide the variety will get.

Bear in mind what it will look like in 10 and 20 years time and be mindful of the aspect in which you are planting your specimen. 

If your choice is going to grow upwards of five metres, is it going to stop the sun from hitting your garden, or will make your house very dark.

Some trees have a damaging root system and should be avoided in all but the largest of gardens. 

The most infamous variety in this part of the world is the variegated poplar or Populus candicans (pictured below).

Be careful when planting trees in your garden

I say infamous because about 30 years ago there must have been some garden centre or nursery who made millions — as every second garden, if not more, seemed to have one of these attractive looking trees growing in its midst.

The aesthetically pleasing foliage is what the tree is grown for, new growth starting off a blush pink as the buds open in spring, opening up to full leaves of white mixed with green.

It was recommended for small gardens as it was marketed as dwarf. But dwarf was meant in poplar terms, it can still reach a height over 10 metres or 30 feet. 

But the reason for its infamy, and why I could never recommend it as a garden plant is that the root system is a menace.

It’s a quick-growing tree and to produce that speedy growth, the roots travel far and fast in search of water and nutrients allowing next to nothing to stop it in its quest. 

Loving septic tanks and leaking water pipes, these have provided the thirsty roots with much loved moisture.

Poplars will do untold damage to these tanks and pipes as soon as they get a hold, as well as patios, footpaths — even house foundations don’t prove a deterrent to these vigorous bullies. 

I have often seen suckers appearing from the root system in the middle of lawns up 20 metres away from the original plant and indeed the roots can travel up to 60 metres wreaking havoc as they go. 

It was only after about ten or more years, that this structural damage became apparent to garden owners and people were clamouring to get them out of their gardens — as much as they sought to get them into them 10 years previously.

Most trees, you will be glad to hear, are much better behaved, but it does illustrate the point that some time and thought should be given to choosing what is going to be an imposing influence — and friend — in your garden over the next number of years.

If choosing for pure elegance and as a statement piece then, provided your garden is big enough, look no further than Cornus contraversa variegata. 

Known as the Wedding Cake Tree because the branches create a fabulous tiered effect as the tree matures, it really is a living work of art. It’s slow growing however. 

As a poor student this gardener purchased one for my parents 25th wedding anniversary, I still remember, it cost me £200 punts and believe me that hurt as a student, but being the perfect son I arrived home from Orchardstown Garden Centre in Waterford where I was doing my work experience year, one weekend with the Cornus. Now 25 years later it has developed into a magnificent specimen.

However, during the intervening years I had to stop myself from pruning it and interfering with the shape — and thank God I did. 

It often looked like it needed attention and bits looked wrong, but as is often the case with nature, once left to its own devices it has blossomed into something really special.

You do need a garden of a certain size for it will grow to an eventual height of 8 to 10 metres with a diameter of five to six metres. One of the finest specimens you are likely to see in Ireland can be seen in Mary Byrne’s garden, ‘Hillside’ in Annmount, Glounthaune. 

This garden is open from time to time and for groups. Next time you see it advertised, make your way to see the Cornus, if nothing else.

Cornus alterniafolia argentea the Silver Pagoda Dogwood, will provide you with the same statement piece, but with an altogether more delicate feeling, the leaves being slightly smaller, indeed the overall height and spread will be less than that of contraversa variegata, never growing higher than 4 metres.

Similarly Cornus alternifolia ‘Golden Shadows’ will remain relatively low and is an ideal choice for a small or medium specimen tree. 

It’s beautiful shape and habit is further complimented by the green and gold foliage which takes on beautiful copper hues during the autumn before it sheds totally for the winter.

All of the Cornus or Dogwoods mentioned will produce panicles of white flowers during spring but often go largely unnoticed on ‘Variegata’ and ‘Argentea’ as the foliage is similar in colour but on ‘Golden Shadows’ the contrast between foliage and flower is another reason to introduce this beauty to your garden.


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