FAQ

Planting and Growing

How many Leylandii do I need to form a hedge?

Leylandii should be planted between 2 and 3 feet (60-90cm) apart.

If you are going to grow your hedge very tall (over 15ft or 5m) then plant them 3ft (90cm) apart.

If you want a quick screen then plant them 2ft apart, but you will get just as good a hedge at 3ft apart, it will just take about a year longer to “fill in” to form the screen. However, planting at 2ft apart will cost more as you will need more plants – sometimes a good compromise is to plant at 2’6” (75cm) apart.

Our online hedging store Evergreenhedging.co.uk has a Hedge Spacing Calculator to help you work out how many you need.

What is the best time of year to plant Leylandii?

You can plant pot-grown (sometimes called container-grown) Leylandii at any time of year. If you plant them from November to February, they will need less watering over the growing season (March to October) than those planted during the growing season as they will have developed root systems in mild spells over the winter months.  It will be worth keeping an eye on them to make sure their roots don’t dry out in dry or hot spells of weather.

If you plant between March and October, your Leylandii will need to be watered over the growing season for the first year. See our sections on Planting, Establishing and Maintaining a Leylandii Hedge for more information.

How do I plant Leylandii?

Planting your Leylandii properly is essential for successful establishment and quick growth early on. We have full instructions on how to plant Leylandii. Please click here.

How quick do Leylandii grow?

Under good conditions the different types of Leylandii will grow the following amounts:

Green Leylandii - up to 3ft (90cm) a year.
Leylandii 2001 - up to 3ft (90cm) a year.
Leylandii Castlewellan Gold –up to 2ft 6in (75cm) a year
Leylandii Gold Rider – up to 1ft 6 (45cm) a year

What conditions do Leylandii need to grow and establish well?

Leylandii need to be planted well, fed well and watered well to get them to grow and establish properly. Like all plants, they will also grow quicker in full sun. Windy conditions will slow the growth down but they will take the wind well as long as they are staked for the first year.

The best feed (fertiliser) to use is a Controlled Release Fertiliser such as Multicote or Osmocote that feeds for 12 months. This provides all the macro and micro nutrients they need for the first year. In general, after the first year, they should have a large enough root system to find their own nutrients.

Rootgrow is a friendly fungus (mycorrhizal) that can help your plants form a huge secondary root system. This aids growth and establishment, especially under dry or difficult conditions.

How far from a wall or fence should I plant Leylandii?

If you have space, plant them 3ft (90cm) or further away but if space is limited to can plant them as close as 18 inches (45cm) away from a fence or wall. You may need to trim the branches on the side of the fence until the hedge “fills in” to prevent them pushing against the fence. Once the hedge fills in, no light will get to the wall/fence side of the hedge and so no branches will grow. This is not a problem as long as the hedge or fence is not removed.

You need to ensure that you can reach the other side and top of the hedge from your side of the fence, if the fence is not on your property. If the hedge is on your property, you are responsible for maintaining the hedge and keeping it trimmed so it doesn’t grow so big that it damages the fence or wall.

How narrow can I keep my Leylandii hedge?

If you trim your Leylandii hedge every year, you can keep it as narrow as 18 inches (45cm). Just trim it back to the same width every year from the start.

Will larger Leylandii plants establish well or is it better to plant smaller plants?

Larger Leylandii plants will establish and grow away quickly if they are planted properly. Leylandii have been selected over the years to establish well from larger plants. If you want a quicker screen, then plant larger specimens as this will save time.

How do I get my Leylandii hedge to thicken out and become dense?

Trim your Leylandii hedge immediately after planting if there are branches coming out further or higher than you want the hedge to be. Trim the sides back to the width and height you want twice a year. This will encourage the shoots within the hedge to branch out and “fill in” the hedge to form a dense screen.

When do I cut of the tops of my Leylandii trees?

Leave the tops of the Leylandii trees until they get to within 6 inches (15cm) of the height you want your hedge to be, then trim them off. This will allow them to branch out to form the top of the hedge. You can do this at any time of the year.

How long will it take to form a good, dense hedge?

It depends on the growing conditions but under good conditions, your Leylandii should thicken out to form a good screen in about 2 years when planted at 2ft (60cm) apart and 3 years when planted at 3ft (90cm) apart. Planting them well is extremely important to get good growth.

What is the difference between bare-root, rootballed and container or pot-grown Leylandii?

Bare-root plants are plants that are dug from the field in the winter months (November to March) and the soil is shaken off the roots. We do not recommend planting Leylandii from this method.

Root-balled plants are plants that are dug up from the field in the winter months with a ball of soil around the roots. The rootballs are then wrapped in sacking to keep the soil around the roots from falling off. This method is often used successfully with plants such as Laurel but is not a reliable method with Leylandii.

Container-grown or pot-grown plants are plants that are grown in pots or containers. Each year they are potted on into a larger pot to provide them with more feed and compost to grow. Most Leylandii are container-grown as this is the most successful method of establishing and growing them.

Established Leylandii Hedges

I have just bought a house with a large Leylandii hedge, can I reduce the size of the hedge?

You can reduce the height but be careful about trimming the sides of the hedge or Leylandii trees. Always leave green foliage on the sides of the hedge as Leylandii will not shoot back from the older, brown wood (see below). When we moved into our nursery, we had a row of Leylandii trees that had never been trimmed and were about 20ft high. We cut them down to about 10ft in height and trimmed the sides. Now they are great examples of thick, dense Leylandii hedges which provide shelter for our polytunnels and screen us from our neighbour.

When is the best time to trim my Leylandii hedge?

It is best to trim your Leylandii hedge in late spring or summer as this gives your hedge a chance to recover and put on a bit or re-growth before the winter. However, watch out for birds’ nests as it is illegal to disturb nesting birds

How often should I trim my Leylandii hedge?

Trim your Leylandii hedge once a year, every year. If you trim it more often, the hedge doesn’t get a chance to recover and put on a bit of re-growth before the winter. It also makes it more susceptible to stress conditions such dry or hot weather, cold winters and Cypress Aphid. Recent research indicates that hedges trimmed only once and those trimmed in the late spring or early summer, are unlikely to suffer from any problems.

My Leylandii hedge has grown too tall. How can I trim a large Leylandii hedge?

If you have not trimmed your Leylandii hedge for a few years, it may be too tall to reach safely. We use a Henchman Hi Step Platform to trim our hedges. Alternatively, you can buy a long-handled hedge trimmer or get a tree surgeon to do the job.

Will Leylandii grow back from brown wood?

No. Always leave green growth on the sides of the hedge. If you cut back into the brown, leylandii will not re-shoot. This is not a problem if you keep your Leylandii hedge trimmed from the start and you trim it back once a year to the same point. It is only a problem if you let it get over-grown or move into a property with an untrimmed Leylandii hedge. You can trim the height of it as low as you like as long as you still have green shoots on the side of the hedge. If the Leylandii trees are too over-grown or have lost foliage near the ground, it is better to dig them out and start again (see below).

We have seen someone cut back one side of a very wide hedge back to the trunks. The green shoots from the other side of the hedge grew back through but this took five years.  It would depend on how wide the hedge is and how far the green has to grow back through so is a bit risky.  The only other alternative is to start again with a new hedge and keep it narrow from the start.  If a leylandii hedge is cut back to the width you want immediately after planting and then cut back to the same width once a year, every year, you can keep it as a dense but narrow hedge.

Can I re-plant a Leylandii or another type hedge where an old Leylandii hedge used to be?

It is best to get a digger in (if possible) to completely remove the stumps and to dig a trench 2ft deep x 2ft wide (60cm x 60cm). Put in fresh top soil or a mixture of top soil and John Innes No.3 compost as even Leylandii will struggle to get their roots established where a large Leylandii hedge has been removed.

How long do Leylandii live?

Some of the earliest Leylandii planted in the UK in the late 1800’s and early 1900’s are still alive and growing, so the answer is “over 100 years” but nobody knows how long they will live for eventually. The National Collection of Leyland Cypresses (Leylandii) is at Bedgebury Pinetum in Kent where several large specimens can be seen.

What are the alternatives to a Leylandii hedge?

Thuja plicata (Western Red Cedar) is another type of conifer that makes a good hedge or screen. It looks very similar to Leylandii and grows nearly as fast. It will shoot back from brown wood but it is more difficult to grow on the nursery (not when planted out) so it usually costs more than Leylandii to buy.

Laurel (sometimes called Cherry Laurel, Common Laurel or Prunus laurocerasus ‘Rotundifolia’) makes an excellent evergreen hedge. If you do not want a conifer hedge then Laurel is probably the next quickest growing hedging plant.

For other alternatives, see our page Alternatives to Leylandii section.

Troubleshooting

My newly planted Leylandii are going yellow and then brown from the bottom upwards, what is the matter with them?

It sounds like they are just struggling to get enough water. The classic symptoms of drought stress are leaves turning yellow or brown and falling off. This starts at the base of the plant, near the stem (trunk) and works its way up the stem and out towards the tips of the branches. This is either caused by the plants being too dry or too wet.

Plants that are too dry (Drought Stress)

Test the rootball of the plant with your finger, it should be moist but not waterlogged as far as you can feel into the rootball. Newly planted Leylandii hedges need watering at least once a week during the growing season (March to October) and more often in hot and dry weather. Even if it rains, the plants may not be getting enough water. It needs to rain at least ¼ inch (6mm) before you don’t need to water. It is worth buying a rain gauge to measure how much rain your plants are getting. Often in the summer, heavy showers can actually provide very little quantity of rain, yet it seems like it has poured down.

Water around the roots of the plant, not the leaves. Keep testing the rootball of the plant to ensure it is moist and never allow it to dry out.

See our Care section for more details on how to water your newly planted Leylandii hedge.

Plants that are too wet (Waterlogging)

Unless you have been watering your plants a lot and the soil is very compacted and poor draining, it is most likely to be drought stress. However, the roots of a plant will rot if the soil is too wet so the plants can't get enough water to the leaves and, as a result, they show the same symptoms as when they are too dry. Wet conditions often occur on heavy clay soil especially when the plants have been planted into compacted soil. Ideally, a hole about twice the size of the plant’s rootball should have been dug and the soil broken up for at least 6 inches (15cm) below the rootball of the plant. This allows the roots to get away easily and any excess water to drain away. The rootball of the plant needs to be kept moist at all times but it doesn't want to be sitting in water. Push your finger as deep into the soil as you can to see if the soil is too wet. If the soil is really soggy then they are too wet. You could try digging up one of the trees (probably the worst affected plant) and see if the soil below is very wet but only if the trees have been planted within the last 12 months. If the soil is too wet, cut down on the watering and just water the plants when they need it. Keep testing the rootball of the plant to ensure it is moist and never allow it to dry out.

Plants can also show drought symptoms when the root system is damaged on planting or after even planting. (especially rootballed rather than pot-grown plants). Always ensure care is taken not to disturb the roots and that the plants are staked to prevent the wind from rocking the plants and breaking their roots after planting.

I have planted a row of Leylandii and some have survived but some have died, yet I have treated them all the same. What could be the problem?

It is likely that the conditions for growth are difficult. This could be poor planting, compacted soil, too dry or too wet conditions. Under difficult conditions, in any population of plants or animals, some will survive and some will not. Try to assess what is causing the problem and correct it before the plants suffer further. Check they were planted correctly with a big enough hole and that the soil underneath the plant was broken up so the plants could get their roots into the ground. Check they are not being over or under-watered. Check, also, that there is not a patch of ground that has been poisoned or polluted before or after planting.

My established Leylandii hedge has developed brown patches this spring, what could this be?

This is likely to be over-enthusiastic hedge trimming, salt damage or attack from Cypress Aphid.

Trimming your hedge very hard so that there is very little green foliage left on the hedge and trimming your Leylandii hedge too often can cause patches of brown to appear especially when the plants are under stress (such as in very hot or dry conditions). It is best to only trim your hedge once a year. Trimming it too often doesn’t give your hedge a chance to recover and can create a lot of “thatch” or dead material in the hedge. This can act as a site for disease which can cause brown patches. It is worth raking the hedge or brushing it with your hand, after trimming your hedge, to remove any dead material. This will also increase the air flow within the hedge and help prevent any further brown patches.

Cypress Aphid can attack Leylandii and other conifers in the late winter and early spring (normally January to April) but the damage is not seen until early spring. There is good evidence that Leylandii that are trimmed back in late autumn are more susceptible to attack especially if they are trimmed back very hard so trim your Leylandii hedge in late spring or early summer (but watch out for nesting birds).

Leylandii are fairly tolerant to salt but they can be damaged by high concentrations of salt either from the sea or, where hedges are planted very near main roads, from gritters that salt the roads in icy weather.

Cut out the brown patches - as they will not re-shoot - and try and encourage branches from nearby parts of the hedge to grow back over the brown patches.

In summary, to avoid brown patches in Leylandii hedges:

  • Trim your hedge only once a year

  • Trim your hedge in late spring or early summer

  • Brush out any dead material from the top and sides of the hedge after trimming

  • Check your Leylandii hedge from January to March for Cypress Aphid, if you see a greeny-brown coloured “greenfly” 2 or 3 inches inside the hedge, then spray with an insecticide such as Scotts Bug Clear Ultra or Bayer Garden's Ultimate Bug Killer.

Plants in my established Leylandii hedge are dying out one by one. The problem is moving along the hedge each year.

This could be caused by lack of water or by a soil-borne fungus such as Honeyfungus. Honeyfungus will attack most plants including Leylandii and spreads through the soil by black “bootlace” structures called rhizomes. The only way to prevent further spread is to put a barrier in the soil such as a pond liner to the depth of about 18 inches (45cm) depth. See our section on Diseases for further information on Honeyfungus.

I have a row of large Leylandii and they are starting to lose their foliage at the bottom. What could be causing this?

If a row of Leylandii trees are left to grow tall, they will eventually start to compete with each other for water and light. If they struggle to get enough water from the soil they will not be able to supply water to all their foliage so they tend to shed their lower foliage in favour of the new fresh growth, therefore making them bare at the bottom.

Removing every other Leylandii tree in the row may be the only option to prevent them losing more of the lower foliage.

Trimming your hedge from the start and keeping it a reasonable height will also prevent this.

I have a row of large Leylandii and they are starting to lose their foliage at the bottom. What could be causing this?

If a row of Leylandii trees are left to grow tall, they will eventually start to compete with each other for water and light. If they struggle to get enough water from the soil they will not be able to supply water to all their foliage so they tend to shed their lower foliage in favour of the new fresh growth, therefore making them bare at the bottom.

Removing every other Leylandii tree in the row may be the only option to prevent them losing more of the lower foliage.

Trimming your hedge from the start and keeping it a reasonable height will also prevent this.

Leylandii Law and Neighbourly disputes

Do I need permission to plant a Leylandii hedge?

In most cases, you do not need permission to plant a Leylandii hedge, although some developments and properties have Covenants that can stipulate what type of hedge you can grow. The details should be in your deeds.

My neighbour has a large Leylandii hedge that grows over onto my property. Can I trim it back?

It is your neighbour’s responsibility to maintain their Leylandii hedge so it would be worth having a polite chat with them before you trim the hedge. They may even trim it for you.

If they are unwilling to trim it, you have the right to cut branches or roots back to the boundary. By law, any trimmings that you cut are still the property of the owner of the hedge, so check with them what they want you to do with them. In the interests of neighbourly relations, don’t just throw it back over the boundary.

My neighbour has not trimmed their Leylandii hedge and it has grown very tall. How do I get them to trim it back?

The best way is to ask them politely to trim the hedge back. If you politely explain to them what the problem is and how it affects you, you may be able to come to an agreement over what height it should be kept at. You could invite them to your home so they can see the hedge from your property.

If talking to your neighbour does not work, you must try mediation before you can complain to the council. Another option is to take legal action but this can be costly so check first. For more details see our section on Leylandii Law.

My neighbour has a very large Leylandii hedge that has not been trimmed and a branch has broken off and damaged our greenhouse. Are they liable for the cost of repairs?

They are responsible for maintaining the hedge. If it has damaged your property, your neighbour could be liable to the cost of repairs or for compensation.

Other FAQ’s

Will Leylandii roots cause damage to my property?

Most trees growing near buildings will not cause a problem. There are many trees that have been growing near buildings for years so it would be wrong to assume that all trees growing close to buildings will cause damage. Factors such as the height of the hedge, soil type and the extent of the foundations of a property will determine whether roots will cause damage.

Many factors, both of the site and tree, can affect root spread. Roots grow in proportion to the height of the hedge. If a Leylandii hedge is kept to a reasonable height 2-3m (6-10ft) then the root system will be much less substantial (and much less likely to cause damage) than if the trees are left to grow to 10m (30ft). Roots often extend for a radius wider than the hedge height.

Structural damage is generally limited to properties on shrinkable clay soils. Trees taking moisture out of these soils can cause soil shrinkage and this can result in subsidence. Conversely removing large trees from clay soils can cause the ground to swell, again leading to structural displacement.

Buildings built before the 1950s are most at risk, as they frequently have foundations only 50cm (20in) deep.

Drain damage - roots may block drains, which burst as a result. This can lead to the formation of cavities as the water from the drain flows into the soil. In general, roots will not break into drains but will enter existing cracks and poorly sealed joints. Older drains with poor seals and rigid joints are most susceptible.

Is Leylandii any use for timber? I have some rather large logs that I thinking of cutting into beams to construct a bridge to cross a small stream

The timber from Leylandii is naturally semi-durable. It would be good for constructing small bridges or pergolas in the garden.

What are the environmental benefits of Leylandii?

Leylandii are good nesting sites for birds.

Leylandii also filter out particulates from the air. Particulate pollution is a serious global problem adversely affecting human health, especially in urban areas. According to the report from the World Health Organisation in 1999, more people are killed prematurely by the effects of this pollutant than from car accidents. Research at Southampton University in 2000 has highlighted Leylandii’s ability to absorb pollutants. Results produced by the researcher, Gail Taylor “suggest Leylandii can improve air quality by 40 per cent, as its complex foliage structure is much better at trapping the smallest particulate pollutants than deciduous species”. Perhaps we should all plant Leylandii hedges along our roadside boundaries.

Where can I get Leylandii seed?

Leylandii are grown from cuttings, not from seed, so you will not find any seed available. Until recently, it was thought that Leylandii didn’t produce viable seed, however, in 2011, James Armitage sowed seed he collected from females cones on a mature Leyland Cypress in Wisley Garden. These produced a Leylandii seedling for the first time under controlled conditions, showing it is possible to grow Leylandii from seed. However, it is still uncertain whether the parentage was mixed as there are suggestions that Leylandii is self-sterile and may need a compatible pollen donor. At Wisley, a specimen of Nootka Cypress (one of Leylandii’s parents) grows near the mature Leylandii and may have cross-pollinated the tree.

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