Planting a hedge
This information 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 TCV (The Conservation Volunteers, formerly BTCV) "Hedging - A Practical Handbook". The latter is available online from TCV here if not currently in print or you may be able to find second hand copies.
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 TCV 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:
- Decorative feature
- All year round cover
- Secure boundary
- Avoiding poisonous plants
- Keeping children, pets, animals in/out
- User friendliness - i.e. no thorns!
- Variety of plant species for interest/wildlife value
- Something that reflects the change of the seasons
- Type of hedge required - informal or formal
- Space available and shading considerations
Some of these criteria are mutually exclusive so you may have 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!
Hedges need light and do not favour being planted in tight to close boarded fences. They can end up growing away from such a fence. If you plant a hedge against a south facing close boarded fence then the hedge growth is going to be relatively slow.
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. Hornbeam has an advantage over beech in that it is deeper rooted and therefore more drought tolerant. 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.
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. Do not exceed recommended spacing when planting, expecially if you envisage having your hedge laid in the future. Although obviously wider, I would always recommend a double staggered row of plants where possible; a single row can look stingy. 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. For a mixed native species hedge, I would always recommend at least 75% hawthorn and when planting ensure that three of every four plants are hawthorn. This allows diversity whilst still maintaining a degree of consistency to the appearance of hedge overall. Do not group species other than hawthorn together in a mixed hedge as you will create weak points in the hedge. This applies especially to rose, guelder rose, wayfaring tree, spindle, privet and dogwood. Consider whether you want field maple in your hedge; is is very attractive, but can grow very rapidly and come to dominate a hedge completely - see here and here for two examples.
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. Using a soaker hose can save time, effort and heartache later on and should be under any mulch or sheeting and down at root level if you are planting in a trench.
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.
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."
Before the different methods are outlined below there are a number of general rules which are common to all methods.
- 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.
- 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.
- 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.
- As with any plant, ensure it is planted to the same depth as previously.
The different planting methods are now described separately:
- Slit planting
This is the quickest and easiest method and just involves working a spade backwards and forwards in the ground until sufficient space is made to insert a single plant into the slit from the side so that the roots are disturbed as little as possible. This method is only suitable with good soil conditions using small plants without dense root systems.
- Pit planting
Here individual holes are dug for each plant. You will have to use this method or trench planting for larger plants. You should experiment whether pit planting is practical with your soil type or whether trench planting is going to be easier. With pit planting you must ensure that soil makes good contact with the roots - you can't just pile it in on top. To do this tip crumbly soil down onto the roots whilst gently shaking the plant to facilitate this before filling in the hole fully.
- Trench planting
Your trench will need to be about 18 inches wide for a double staggered row. If your test of the soil conditions have already indicated that double digging is necessary you should consider doing this before taking delivery of your plants since it will be very time consuming. As with pit planting, you need to ensure that the soil makes good contact with the roots before firming the soil down with your foot.
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:
- Suitable for short lengths of hedge. This must be done with care to minimise disturbance to the hedge.
- Organic mulch
- TCV recommends that a four inch thick layer should be applied immediately after planting to be effective. Since so much is required, you should give some thought as to whether you can make or obtain any of this inexpensively in advance.
- Black polythene mulch. This is sold in rolls for hedging use and must be a suitably thick grade to last three years. The edges must be securely bedded into the ground either side of the hedge. It has good moisture and heat retention properties. The sheet should be weighed down with earth or gravel to discourage nesting vermin.
You can slit plant small plants through the polythene sheet, using a knife to make the correct size cut for your spade and plant carefully through the hole. This requires good soil and care to avoid damaging the sheet.
You can also apply the polythene mulch after you have planted the hedge by pruning the plants obliquely at 6 inches high so that they can easily and cleanly pierce the polythene. Hedgeplanting references also recommend this as a way to stimulate vigourous bushy growth from the outset, particularly with hawthorn but I have yet to observe it in practice!
- Herbicides. It is good environmental practice to keep the use of herbicides to an absolute minimum. Try to use products with the least environmental impact and follow the instructions carefully.