Planting Hedges

Trimming Unlaid Hedges

Trimming Laid Hedges


Hedge planting - an overview 

Introduction

The information provided here is intended to help someone to select and plant a hedge themselves in the UK using native woody stemmed plant species.

It is not intended to give a complete and definitive guide to all aspects of hedge propagation, species characteristics, planting, aftercare and pruning.  If this is required, I recommend you refer to either Murray Maclean's "New Hedges for the Countryside" and/or the British Trust for Conservation Volunteers (BTCV)  "Hedging - A Practical Handbook".

Both these books are excellent with, inevitably, some overlap of coverage.  As you would expect from the title, Murray Maclean's book covers all aspects of hedge propagation in great detail.  He emphasises larger scale mechanised planting and management regimes for farms and propagation considerations for commercial growers.  The BTCV book places more emphasis on manual planting and management techniques, conservation and the management of mature hedges.

What do you want from your hedge?

Unless you have already decided what plant species you are going to use, you need to decide which of the following are important to you:

Some of these criteria are mutually exclusive so you may need to prioritise your requirements.

Suitability of location

It is a good idea to have a look for similar types of hedge in the neighbourhood to see what plants grow well in your locality.  This is not just a question of soil type - rainfall, drainage or lack thereof, altitude, latitude and exposure to the elements are all significant factors.  Remember that if it's a native species and not growing in your locality then there is probably a good reason!

There are also safety aspects and consideration for others to be taken into account.  Will the hedge eventually cause visibility problems to road users or vehicles leaving your land?  Will it unreasonably reduce light levels?  It is a good idea to ensure that neighbours are consulted both out of courtesy and because you may one day want to trim the hedge from their side!

If planting in a garden, have a look at similar types of hedge nearby to see how tall and wide they can get.  Remember that the more compact the hedge, the more often it has to be trimmed!  Ensure that the line you intend to take for planting will give adequate width for both sides for the hedge as it grows.

All year round cover

This pretty much restricts you to beech, hornbeam, yew, holly or privet.  Although the leaves of beech and hornbeam hedges die in the autumn, they remain attached until pushed off by the new buds in the spring so remain an effective screen through the winter months.  Yew is slow growing and highly poisonous and should not be used where there are stock.  Yew, beech and hornbeam all have the advantage that they can grow tall whilst being kept dense and relatively narrow.  In a garden setting a mixture of green and copper beech can look very spectacular.  Holly is very slow growing and tends to suppress other plants once it finally does become established.

Secure boundary

If this is a requirement you should go for a preponderance of thorn species, preferably hawthorn.  Blackthorn has the disadvantage that it suckers vigourously and will encroach either side of your hedge.  The deterrent nature of a thorny hedge cannot be overestimated and it has the advantage over any fence or wall that it is not prone to vandalism and looks attractive as well.

Quantity and type of plants required

As a rule of thumb you should allow one plant every 9 inches, so whether planting in a single row or a double staggered row the number of plants required is the same.  For a mixed hedge, many nurseries can supply a hedging mix comprising predominantly hawthorn with a small number of other hedge plants included as well.  Some may offer a stock hedging mix and a conservation hedging mix, the latter having a larger proportion of plants other than hawthorn.

The size and nature of the plants required will depend on both your budget, your patience and whether your require a formal or informal hedge (see below).  Remember that the larger the plant, the larger the roots, and even with some trimming of the roots, more effort is going to be required to plant them.  This is especially true with transplants which will already have a dense and well developed root system.

You should also consider whether any hedgerow trees are required.  Twenty two yards is the minimum distance that should be left between hedgerow trees so that they remain sufficiently spaced at maturity and do not completely dominate the hedge.  One option is to plant them slightly inside the line of the hedge though this may require additional stock protection.

Formal and informal hedges

Formal hedges are generally single species hedges found in gardens which are trimmed regularly to maintain a very uniform and tidy appearance and to keep them as compact as possible.  They tend to be very dense and where formed of hawthorn, for example, it is likely to be impossible to separate out individual stems of the plants.  Since regular trimming makes them so dense they should not need laying.  The thickness of formal hedges can be encouraged by using 'feathered' plants with multiple leaders and using stakes and horizontal wire along the line of the hedge to train the leaders.  The size of plants used in a formal hedge is likely to be bigger than that for an informal hedge since the initial appearance is more important.  As the hedge grows the plants entwine into each other.

Informal hedges are most commonly farm hedges and may comprise several different species though hawthorn usually predominates because of its general hardiness and stockproof qualities.  These hedges may be trimmed every few years except where proximity to a road requires more regular trimming to maintain visibility.  If the hedge grows very tall but is still thick at the base its height may be drastically reduced and then allowed to grow up again.  Alternatively, if gaps have appeared at the base then an informal hedge may be allowed to grow up and then laid to rejuvenate it.  As well as reducing overall costs, this less intensive management pattern increases diversity so that collectively, informal hedges have greater wildlife benefit.  Informal hedges can use either 'whips' which are hedging plants with out significant side shoots or 'feathered' plants.  Whilst whips are cheaper, a hedge planted with whips will grow straight up rather than out and spaces between the plants will be slower to fill in.

Identifying aftercare requirements

If planting a new hedge you may need a fence to protect it from stock at least until it gets established.  This must be far enough away from the hedge to prevent them from reaching it - not alongside it!  Any grass/herb stretch by a hedge forms a valuable wildlife habitat in its own right as does a ditch alongside a hedge.

You also need to consider hedge pests such as rabbits which will require the use of rabbit guards or for a heavier duty solution rabbit wire.  Rabbit wire is hexagonal mesh wire which should have the bottom six inches buried facing away from the hedge to prevent the rabbits burrowing straight underneath.  Deer may require tall fencing both sides for a newly planted hedge to be able to survive making it a serious and costly undertaking.

You also need to consider at the outset what weed control you will employ in the early years to prevent the new plants being swamped by a rampant herb layer.  This could be individual mulch mats, a mulch layer, polythene sheeting or, for shorter lengths of hedge, hand weeding.  You should not use a strimmer anywhere near your newly planted hedge since this will damage the base of the stems!

In the first summer after planting, your new hedge will need watering if there is a lengthy dry spell.

Preparation for planting

Before selecting your planting method, you should investigate the soil condition along the line of the hedge to ascertain the method and treatment most appropriate. Poor and heavy soils will need more preparation initially to break up and fertilise the soil and this effort will be rewarded later on as less weed control will be required as the hedge grows vigourously.

If the line of the hedge is to be cultivated prior to planting then this should take place to 'double digging' depth and poor soils should be fertilised below the root level.  Planting should take place from October to March, except for evergreens which should be planted in early autumn else in spring to reduce frost damage.  Generally autumn planting is preferable to give the hedge as much rain as possible before the summer.  Planting should not take place, however, when there is a frost nor into very wet ground.  Delivery of the plants should take place as close to the day of planting as possible.

If a ditch is being dug at the same time as a hedge planted then the ground where the hedge will be planted should be cultivated and fertilised as necessary before soil dug from the ditch is tipped on top.

It is most important that the plant roots are not allowed to dry out before planting.  This occurs very quickly once they are exposed to the air.  Roots should be kept in the dark and damp in strong plastic bags tied firmly above root level and with the roots watered as necessary.

The following preparation and planting regime has been used successfully and recommended by a Canadian contributor with a knowledge of permaculture:
 

"The following methods were used for weed suppression and ground preparation which saved a lot of time digging and weeding. This was done in late September 2000, when we start to get our autumn rainy season.
  1. Slash the grasses and weeds back, leave them lying on the site.
  2. Add 1/2 inch one year old composted sheep manure.
  3. Cover the lot with a thick layer of flattened cardboard boxes.
  4. Cover with mulch, I used 3 inches of one year old leaf mold (crawling with soil-building insects) then covered with new leaves when they fell.
  5. Place cut branches over the site to keep things from blowing around, and to capture passing leaves.
In late November, when I planted the hedge, the soil under the cardboard was friable, the weeds and grass, along with their roots were gone, and digging small pits for the plants was a dream, right through the softened cardboard, rather than trying to dig into concrete, which would have been the case, had I tried to dig into the thick roots of the grasses and weeds of late summer. 

By adding mulch over this in the summer 2001, I have had only a few wizened thistles to hand weed. Otherwise, the hedge plants are thriving, and grasses are held in check."

Planting methods

Before the different methods are outlined below there are a number of general rules which are common to all methods.

  1. A line or guide of some sort should be used to ensure that the line of the hedge runs true.  You cannot do this sufficiently accurately by eye.  Have the line or guide slightly to the side so that it is not disturbed or obliterated during the planting and work a fixed distance from it.
  2.  
  3. It is most important that the plants are well firmed down with the feet once planted so that the soil makes good contact with the roots of the plant.
  4.  
  5. Allow the roots to spread out as naturally as possible, even when slit planting.  Excessive or awkward root growth can be trimmed off before planting.
  6.  
  7. As with any plant, ensure it is planted to the same depth as previously.
The different planting methods are now described separately: Weed suppression

Your hedge needs help in the the first couple of years until it can dominate and suppress the grass and herb layer around it.  There are a number of options some of which may be used in combination:


Trimming of Laid and Unlaid Hedges 

Trimming unlaid hedges

You can apply the normal rules for pruning to hedge shrubs with a view to encouraging dense growth from top to bottom of the hedge.  If the intention is to allow the hedge to grow up for laying then you can just trim the side of the hedge and keep the top level for appearance.

Trimming laid hedges
1. The overall objective is to make the hedge as thick as possible and to maximise the intervals between laying, which is a time consuming and relatively expensive activity.  There is a trade off between getting the hedge tall again as quickly as possible and thickening it up as I am forever telling customers when I am laying hedges!
2. Whether trimming mechanically or by hand, the direction of trimming should follow that of the laying so that you are trimming with rather than against the lay of the hedge.  This minimises the damage to stems as they are cut.  If trimming mechanically, the equipment used must be able to cut the regrowth cleanly and with minimum damage to the stems.  Torn as distinct from cleanly cut stems are not only unsightly but promote disease and dieback in the stems.

This laid hedge has been well trimmed
                    mechanically and is consistently thick and even
This laid hedge has been well trimmed mechanically and is consistently thick and even
3. The first time a laid hedge is trimmed it should be cut just above the top of the stakes.  Where possible, the sides should be trimmed at an angle, the wider the hedge, the shallower the angle. 

Wider hedges, which are the most beneficial for wildlife, are easier to achieve where you have plant species which will sucker such as blackthorn and where there is no ditch to keep clear.  Ideally, the new growth at the outer edges of the hedge should be cut as low to the ground as practical.  As well as getting the hedge to bush out from as low as possible, this will also thicken the hedge up at all levels.  If you just "top" the hedge, you will end up with a lot of undivided stems 4ft or so tall, which is not what you want.
 


This predominantly ash hedge has been trimmed by hand two years after laying.  By stepping the cuts as shown the hedge will bush out at all levels as it starts to regrow
4. Where the requirement is for the normal informally managed country hedge rather than a formal and annually trimmed town hedge, trimming need not take place more often than every two to four years.  As well as saving time and money, this also benefits wildlife since you only get blossom and fruit from previous years' growth.
5. Successive cutting of the hedge should be further out and up each time to further promote thickening of the hedge.  Repeated cutting at the same level is bad practice and causes progressive damage to the hedge. 

A tall well managed hedge is likely to have several horizontal lines visible in winter where it has been cut mechanically in the past.  Once a hedge reaches the maximum height required, then providing, there is no requirement to lay it to fill in any gaps, it is quite acceptable to significantly reduce the height of the hedge once more.  This will involve cutting through relatively thick wood and is likely to require the use of a saw attachment rather than a flail.  The hedge can then be allowed to grow up again and managed as before.
 

6. It is generally reckoned that the best time to trim a hedge is late winter when there are no berries or fruit left in the hedge for the birds but that you should avoid doing this when there is a hard frost.

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