Hedges 1 Any Questions?

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Q. I have a large west facing garden to the side of my Suffolk Cottage, bounding against a road. In April this year I planted a Laurel hedge along this boundary, I hope to eventually have a dense informal hedge around 6-8 feet high. The Laurels were 4ft high when planted and they have grown strongly over the summer, they are now around 5-6ft but are starting to look a little leggy. How do I go about cutting the hedge with the aim to achieve a dense high hedge? I very much hope you can help with this question as I have hunted high and low on the WW web and found very little advice.

A. If left to their own devices with lots of space, laurels will grow into a bushy tree / tall shrub about 20ft + high. It seems that this is what yours are in the process of doing, particularly as you say they have grown strongly. To get them to bush out, particularly low down, you need to prune quite hard.

Q. I have a two-year old grapevine in my greenhouse. I know that I should take off any grapes whilst still young this year, but how do I prune it? When I bought it, someone talked about cutting off leaves after a certain joint, but that person is no longer available for advice. Grateful for any information.

A. You need to tie-in the leading shoot so that your vine develops a good strong leader, allow it to grow unchecked. Any laterals that grow from this should be pinched back to five or six leaves and their side-shoots to one leaf.

Q.  I have a beech hedge approx 8ft high. What is the best time to prune it back and do you advocate the method of cutting back on one side the first year, and then cut back the other side the following year. I also want to reduce the height, what is you advice on going about this task?

A. It depends on how drastically you wish to cut the hedge back. For general maintenance of a beech hedge, two trims a year are fine, once in midsummer and once when dormant during the winter months.

If the hedge is very overgrown then any major pruning should take place in midwinter. Leave it until then if you want to take more than about 2 feet off the height of the hedge involving cutting back into larger established branches.

The cutting one side at a time approach is only necessary for drastic pruning. If you want to reduce the width by cutting into large established branches, then do opposite sides on alternate years. If the cutting back only involves young twiggy growth, then it's not really necessary.

Q. I'd really appreciate any info you might have re a dieback problem I'm having with my laurel hedge. About 2 months ago a three feet wide section of the hedge appeared frost-damaged - we had 2 or 3 very sharp drops in temp at night during the previous week. The hedge had been well cut back c3 years ago due to building work but was flourishing with lots of lush new growth - I thought its thinning perhaps had made it susceptible to frost damage.

This 3 feet section however has now extended to almost 6 feet wide & appears to be spreading. My neighbour & I are very concerned & would appreciate any advice on how we might save it.

The laurel is c.12 feet high/50 feet long & I think was planted when the houses were built in 1920s - the leaves are fine and small and a light green colour, not dark. The dieback appears to start from the bottom up with leaves wilting, then brown spots, then entire leaf brown and stems browning. Is there a disease that affects laurel? or could the roots be water-logged (nurseries here have been recently selling off plants due to the extraordinary wet weather we have had!) A friend has also suggested cats & their 'ablutions' (another neighbour has two new cats).

A. If those cats can kill off a 12ft high by 6ft wide 80 year old laurel, I'm glad they're in Northern Ireland and not over here! Seriously though I think we can disregard the cats as a factor.

It's difficult to tell without seeing the hedge directly. With such a large old plant, I think the most likely cause will be a fungal disease triggered by several factors that have acted together to weaken the plant. Age, water logging, physical damage - letting fungal spores in - will all have a part to play.

The first thing I would do would be to delve into the hedge and determine how many plants the die-back is affecting, is it just one or is it moving to others? Look carefully at the plants, leaves, stems, trunk for any clues, I presume there aren't any pests or you'd have mentioned them? Are there signs of fungal disease any where? especially low down near the ground, is the bark damaged? Is there anything peculiar about where the damaged plant/s are growing?

Are the branches the dead leaves are attached to dieing too? Snap one or two and see if there are signs of life. If they are dead then cut back into a live part. If they are still alive, things are looking better.

To be honest things don't sound too great and it may be a question of containment if the problem can't be dealt with directly, stopping it from spreading to the next plants on in the hedge. If the problem is containable and stoppable then the good news is that laurels usually recover well from some hard pruning.

Q. I planted a hedge of 25 Thuja conifers in late September, 20 inches apart in a well-prepared trench. The trees run in a North-South direction for approx. 40 ft. and there is a 6 ft. fence to the Western side.

The trees appeared to be doing fine until about a week ago, during recent heavy rains in the UK. On 5-10 trees there are a number of brown leaves, especially nearer the ground that are falling off. I can accept that there may be some loss over the winter. However, some leaves and stems higher on the plants in random locations are turning an almost blue-black colour and falling off. Is this normal, or do I need to take action?

Thanks for your question. It's not always easy to work out what's happening when conifers start dying off. I wouldn't expect the browning off or blackening of stems at all, neither are expected responses for newly planted conifers in such a short time.

A. I think the strongest possibility is an infestation of Phytophthora fungus. The fungus thrives in damp and waterlogged soils so may be in your soil, but the speed at which your plants have been affected implies that there is a good chance that they arrived with it. It kills the plants from the roots upwards and can give the blue/black colour on the stems that you describe. The roots of affected plants are reddish brown or black rather than white.

Some trees, such as Lawson's cypress are highly susceptible to Phytophthora root rot. Nevertheless, root rot is almost always the result of over-watering, root damage or prior drought stress, poor soil conditions, flooding, etc. Pythium and Phytophthora can almost always be found in dead, rotted roots, so may not be the primary cause. Except for highly susceptible species, re-planting with healthy trees should not be a problem if the soil and environment are improved and good horticultural practices are followed

Other possibilities - you'll need to investigate a bit further:

Cure? obviously depends on the cause. If it's Phytophthora there's nothing you can really do. I'd go back to where you bought the plants from, but there's no chemical control available to cure it. The fungus remains in the soil so despite what MAFF say, I wouldn't risk planting the same again. Tsuga heterophylla (Western hemlock - not keen on exposed windy sites) and the ubiquitous Lleylandii (tough as old boots and grows like mad) are resistant.

Q. We have a very long privet hedge that skirts all three sides to our garden.  It is about 3ft - 4 ft high but has got very wide and is encroaching on our beds too much.  How and when do we prune it.  We will need to prune hard, any tips on how we tackle it please.

A. Privet can take very hard pruning, so no real worries about damaging it. Leave it until it's showing signs of spring growth first though. I'd do it a side at a time, prune the side that is causing the greatest encroachment first, and then when that has greened up again, prune the other side. You can do both at the same time, but the plants then have to draw entirely on their reserves rather than being "powered" by the leafy side, the hedge also looks very threadbare until new leaves have grown.

Q. I have a hawthorn hedge that is gives little privacy/cover in the winter months. Removing the hawthorns to plant a new hedge will leave the garden too exposed for too lengthy a period. Therefore I would like to supplement the current hedge by planting evergreens, probably Laurel bushes. My question is, will laurels grow happily alongside the hawthorn. If not what evergreen hedging will ?

A. Yes you can plant laurels between the hawthorns to fill the gaps, but they won't grow "happily" - nothing will. Assuming the hawthorns are fairly mature, anything you plant will have to compete with them and to start with at least from a difficult beginning as what's already there will be well established. Unless you plant anything new a fair distance from the hawthorns - 1m+ then it will be a slow old process - that is assuming the hawthorns don't just simply out-compete and kill off the interlopers.

In short - might work but will take a longer time than if the laurels (or whatever) were there on their own, and it might result in the death of your "new" plants.

Q. What is the best time to plant a laurel hedge?

A. The best time to plant any kind of shrubs / trees / hedging is in the early autumn. September to November. That way there's still enough of the growing season left for the plants to get established before it gets cold. It's not going to be so hot or dry that the plants get stressed or need lots of looking after and come the spring they're all ready and raring to go as they are established already.

The down side is that you don't really see much growth for about 6 months.

Spring, Feb to about May is also good. If plants are containerised however they can be planted at any time of the year as long as they're looked after, but autumn is optimal.