Further Information about Leylandii Hedging

What conditions and soil does a Leylandii hedge need to grow?

Green leylandii hedging conifers (x Cupressocyparis leylandii)

Leylandii conifers are one of the most versatile hedging species, they will grow successfully in all soil types including Clay and Chalk soils. On lighter sandy or chalky soils it is advisable to add some organic matter to the soil to help reduce the drying effects of the summer months. When planting as also advise using a little bonemeal and rootgrow to get the new hedge established quickly. For a full set of planting instructions please take a look at our ‘How to plant a hedge’ page.

Leylandii hedges are suitable for conditions from sheltered to exposed, they are a good choice for coastal gardens too although the tips can get scorched occasionally by the salty spray– but this is only cosmetic, soon covered by the new growth when it comes.

If you are planting a new Leylandii hedge or screen on an exposed site, be sure that the plants are firm after planting and keep an eye on them for the first year or two. Wind rocked plants can fail – if they flap around in the wind a hole will form in the soil at the base of the stem, as with any new hedge this can be fatal if it fills with water.

Because Leylandii are very fast growing, crooked plants that have been blown around can be VERY heavy and hard to get straight again when they have grown! A little time spent monitoring/straightening the new hedge when it is young will go a very long way. It is much easier to stake and secure a small plant.

How many plants do I need?

Gold Leylandii hedging conifers (x Cupressocyparis leylandii Castlewellan Gold)

Planting distance is very much a matter of personal choice and budget but the closer you plant them together – the more quickly you will get a hedge!

As a general guide, when planting a hedge, we would recommend 4 plants a metre for the smallest sizes, 3 plants per metre for medium sized hedging plants and 2 per metre for the largest sizes. You can of course plant them further apart if you don’t mind waiting a little longer for them to knit together.

If you plan on letting your Leylandii trees grow taller as a screen (more than 2.5 metres) we would recommend that your planting distance is about one quarter of the proposed height (so for a 4 metre high screen, we would suggest planting them about 1 metre apart)

What is the best option/size to purchase for a new hedge?

Choosing the right size plant for a new Leylandii hedge

This is very much down to your budget, few hedging species give you so much cover if you have a smaller budget, the smaller starter plants in 9 or 11cm pots will develop into a fine hedge within 4 years or so. Although they will need a little more aftercare in the first couple of years (especially keeping them weeded and watered) they should develop into lovely bushy hedge specimens having so much space at a young age!

Many customers choose the mid-size plants in 2 or 5 litre pots as these are something of a ‘sweet spot’ in that they have a degree of impact from the moment they are planted, are easy to establish yet are still modestly priced.

Our larger Leylandii hedging plants in pot sizes of 10 litres and above are great for instant impact, you only need 2 per metre of hedge to be planted and they will generally give the look of an established hedge very quickly, especially if planted in the spring.

(At Hopes Grove Nurseries we only sell Leylandii hedging conifers grown in pots, this way there is no root disturbance and you can expect 100% success in establishing your new hedge with no more than basic aftercare. Some nurseries sell field grown Rootball Leylandii hedge plants which can give satisfactory results if the weather is kind but establish poorly in harsh conditions. If you are considering buying rootball stock we would recommend that you seek assurances from the supplier that they will replace any failures as they may be considerable in number in a dry spring.)

Advice on trimming Leylandii conifer hedges.

Advice on trimming a Leylandii hedge

Leylandii are a great hedging and screening plant but there is one important thing to remember – they will not re grow if you cut back into the old wood. Once it is brown, it will stay brown and there is no way of remedying this as Leylandii hedges have little or no ability to regenerate from the old wood.

If you are going to keep a Leylandii hedge in good order and not too tall or wide, then it is essential to trim it at least once a year. This will ensure that you are only ever cutting into the new green growth and the hedge will therefore still look nice and green (as well as tidy!) after you have cut it, with no brown patches.

For a new hedge the first trimming will probably involve no more than taking the tips out of any long side growths, for a really dense hedge from the start it is worth sacrificing some height by cutting the tops back, the plants will grow back really quickly and will be far bushier for it.

Once your Leylandii hedge is well established its worth bearing in mind that even if you do trim once a year, the amount of clippings this vigorous hedge produces will be substantial. If this is likely to be a problem, or there is a chance you may not be able to cut it every year then we would recommend you consider a slower growing alternative. We have a number of other conifer hedging species including various types of Thuja and also English Yew, as well as being slower growing they also regenerate when cut back into old wood which can be really useful if your hedge does get out of hand. You could check out our complete range of conifer hedging and screening or consider alternatives from our evergreen hedging page.

If you trim a Leylandii hedge more than once a year, it is possible to get a true ‘show garden’ look, very neat, crisp and precise – more like a Yew hedge but much faster growing! Frequently trimmed Leylandii hedges can look very fine indeed, especially in a garden setting – and there are far fewer clippings to clear up and dispose of afterwards.

However often you choose to cut your Leylandii hedge and whether you use shears or a hedge trimmer, do make sure that they are sharp. Blunt cutting tools will cause unnecessary damage to the growth that remains on the hedge making it easier for fungal spores or other pests and diseases to gain a foothold and infect your hedge.

While there is no hard and fast rule about which time of year is best to trim a Leylandii hedge, there are a few basic rules:

  • Trimming more frequently and lightly is better than an occasional heavy handed trim
  • Avoid cutting Leylandii hedges during very frosty or very hot weather
  • Try not to cut the hedge in wet conditions, the aim is for the cut edges to dry and heal as quickly as possible
  • Use sharp tools
  • Ideally choose a cool breezy day

Feeding and general aftercare of a Leylandii hedge

Leylandii hedges are easy to grow, with a little soil preparation and aftercare you can expect excellent results, you new hedge plants should develop into a fine evergreen screen quickly.

This can be helped by providing a mulch (a layer of organic matter like bark chippings or compost) around your new hedge, not only will this look good it will also stop the soil from drying out so your plants have more water, and it will generally discourage weeds – any weeds that do get a foothold will probably be rooted in the mulch and so are easy to pull up.

The new hedge may need watering in the first summer after planting, if so we would strongly recommend a good soak once a week rather than just spraying them over more frequently. This way the plants get the water they need, but the new roots are also encouraged to seek water and so the plants will establish more readily. Frequent light watering can encourage the roots to stay near the surface which can leave the plants vulnerable to drought if they don’t get their frequent ‘fix’ of water. The easiest way to water a new hedge is with Soaker Hose, especially is the run of hedging is substantial, or a long way away from the mains.

After the first year your establishing Leylandii hedge may benefit from a top up of mulch, at the same time you might consider applying a balanced feed in the spring like After plant to keep the foliage a rich colour and the plants healthy to maximise thier growth potential giving privacy in a minimum amount of time.

Pests, Diseases and problems of Leylandii hedges

The Leylandii hedging conifer is a tough and robust plant of strong constitution and generally suffers from few pests and diseases.  There are however a number of possible problems that a hedge may suffer from, usually when the hedge is under stress and is weakened – perhaps from over zealous pruning or harsh environmental conditions such as a prolonged drought or a long period of waterlogging.

Honey Fungus (Armillaria)

Leylandii hedging and honey fungus

Honey fungus is a fungal disease that affects many woody plants, the disease spreads underground by means of Rhizomorphs that look like strong black ‘boot laces’, affected wood has sheets of white mycelium that smells strongly of mushrooms.

Symptoms above ground include a general weakness of the affected plants which show poor colour and weak growth, the plants may die slowly over time or very quickly, especially if the growing environment causes further stress – a prolonged drought for example. The stems of affected plants may split and crack near the base of the stem, sometime accompanied briefly by clusters of light brown toadstools.

There are no chemical methods of controlling Honey fungus, the best approach is to try and limit its spread. This may be achieved by removing any affected plants including the roots and either sending them to landfill or burning them. Installing a strong, vertical physical barrier around the affected area (such as strong pond liner) will stop the spread, the barrier should protrude 5-10cm above the soil level to be completely effective.

While no plants can be considered truly resistant to Honey Fungus, there are a number of hedging species that rarely succumb to the disease that you may like to consider as replacements. These include Yew, Box, Griselinia, Hypericum, Potentilla, Alder and Cotton Lavender.

Cypress Aphid (Cinara cupressivora)

Cypress aphid on Leylandii hedging plants

This is the most common cause of brown patches on established conifer hedges including Leylandii caused by large greyish coloured greenfly (although by the time the damage is evident the aphids are often long gone). Sometimes the shed skins of the aphids can be seen, other symptoms include a sticky black sooty mould that develops on the sugary liquid excreted by the aphids although this is very much a secondary infection and again, will appear before the browning of the foliage is seen.

Cypress Aphid can be controlled with a suitable insecticide spray which will help to limit the damage. If caught early enough then the brown patches should grow back in over time, this can be hastened by tying in neighbouring healthy shoots to help cover the affected area. This may also be helped by mulching the hedge and applying a feed, ideally in the spring to strengthen the hedge and help it to recover.

High Hedges and the law.

There have been a number of high profile cases over the years where homeowners have let hedges (often Leylandii) become very large to the point that their neighbours have been deprived of light and enjoyment of their own property. This lead to the development of the High Hedges legislation in 2003 which offers affected homeowners a route of complaint to their local council. If the council considers that the complaint is justified, they can take enforcement action although this only happens where all other reasonable courses of action have failed. You can find out more about the High Hedges act by visiting the GOV.UK website