Gardening Guides
Take Care of Your Hedges With These Pruning Pointers
Hedging plants are often called the garden’s architecture. Here’s how to keep different kinds healthy and attractive
Pruning is a huge subject, and it can be confusing to know when and how to do it. Here are a few tips to help you get the best from some popular plants used for hedges.
Many hedging plants are cheap to buy as bare-root plants in late autumn. Not only do they provide an attractive green boundary and good garden structure, but they’re also wonderful for wildlife. The Royal Horticultural Society has divided woody shrub pruning into 13 groups, and hedging falls into several of these, depending on whether the plant is evergreen or deciduous and the chosen variety.
Always check for nesting birds before you do any pruning.
Many hedging plants are cheap to buy as bare-root plants in late autumn. Not only do they provide an attractive green boundary and good garden structure, but they’re also wonderful for wildlife. The Royal Horticultural Society has divided woody shrub pruning into 13 groups, and hedging falls into several of these, depending on whether the plant is evergreen or deciduous and the chosen variety.
Always check for nesting birds before you do any pruning.
Boxwood. Buxus falls into RHS pruning group 8, the early-flowering evergreens that also include plants like camellia and Viburnum tinus.
There’s a great deal of debate about when to prune boxwood, not least because of the disease problems now associated with it in the U.K. Some people say that cutting the tops to a 45-degree angle prevents blight from settling on a flat-topped hedge. And the good news is that boxwood, like holly and yew, will regrow from bare wood; it’ll look unsightly until the following spring but will then resprout with fresh new shoots.
Dipping your shears’ blades into diluted bleach will also help prevent any disease from spreading.
For young, newly planted hedges, cut back in May to encourage new bushy growth. Prune back the new season’s growth when it’s about 4 inches long. For older, established hedges, you can cut in May or June, but any adverse weather conditions, such as scorching heat or late frosts, may affect young growth, allowing disease to enter. For this reason, you may prefer to prune them in August or September, when any new growth has hardened off.
There’s a great deal of debate about when to prune boxwood, not least because of the disease problems now associated with it in the U.K. Some people say that cutting the tops to a 45-degree angle prevents blight from settling on a flat-topped hedge. And the good news is that boxwood, like holly and yew, will regrow from bare wood; it’ll look unsightly until the following spring but will then resprout with fresh new shoots.
Dipping your shears’ blades into diluted bleach will also help prevent any disease from spreading.
For young, newly planted hedges, cut back in May to encourage new bushy growth. Prune back the new season’s growth when it’s about 4 inches long. For older, established hedges, you can cut in May or June, but any adverse weather conditions, such as scorching heat or late frosts, may affect young growth, allowing disease to enter. For this reason, you may prefer to prune them in August or September, when any new growth has hardened off.
Bare-root hedging plants. Young bare-root plants are sometimes called whips because of their long, slim appearance. They often knit together better than larger shrubs, forming a thicker hedge. They also tend not to have side branches, making it easier to attach a spiral guard to the upright stem to fend off nibbling rabbits; you may need to do this until the plants are well-established.
For a good, informal-looking and wildlife-friendly hedge, consider planting hawthorn (Crataegus monogyna). Once established, it produces scented white blossoms in May, followed by red berries in the autumn that are ideal for birds.
When planting young hedging plants, you need to be brutal and cut them back by half to encourage vigorous regrowth and low branching. By spring, the dormant buds below the cuts you made will start to pop out. The following winter, do the same and cut it back by half.
As with other hedges, make sure the bottom is always wider than the top to allow light into the lower branches to keep them leafy.
The Beauty of Bare-Root Plants
For a good, informal-looking and wildlife-friendly hedge, consider planting hawthorn (Crataegus monogyna). Once established, it produces scented white blossoms in May, followed by red berries in the autumn that are ideal for birds.
When planting young hedging plants, you need to be brutal and cut them back by half to encourage vigorous regrowth and low branching. By spring, the dormant buds below the cuts you made will start to pop out. The following winter, do the same and cut it back by half.
As with other hedges, make sure the bottom is always wider than the top to allow light into the lower branches to keep them leafy.
The Beauty of Bare-Root Plants
English yew. Taxus baccata is a forgiving hedge when it comes to pruning. English yews are slow growers, but they make wonderful thick hedges, which also lend themselves to topiary.
If you’re planting young hedging plants from October to March, trim back any straggly side growth. But don’t cut the top growing point, or your plants will never recover the same vigor or grow properly in height.
For the first few years, trim your hedge in April, July and October in a tapered shape, allowing light to get to the base. When you have the desired height, let it grow about 4 inches higher than you want, and then you can start to reduce the top slowly, little by little.
Make sure when you plant yews that the soil is well-drained. They won’t tolerate being waterlogged and could be susceptible to Phytophthora root rot.
To renew an old yew hedge, you can be brutal and cut it down almost to ground level — 6 to 10 inches — in early spring. New growth will appear, but the hedge could take a few years to recover properly.
If you’re planting young hedging plants from October to March, trim back any straggly side growth. But don’t cut the top growing point, or your plants will never recover the same vigor or grow properly in height.
For the first few years, trim your hedge in April, July and October in a tapered shape, allowing light to get to the base. When you have the desired height, let it grow about 4 inches higher than you want, and then you can start to reduce the top slowly, little by little.
Make sure when you plant yews that the soil is well-drained. They won’t tolerate being waterlogged and could be susceptible to Phytophthora root rot.
To renew an old yew hedge, you can be brutal and cut it down almost to ground level — 6 to 10 inches — in early spring. New growth will appear, but the hedge could take a few years to recover properly.
Informal flowering hedges. There are some lovely plants that can be used as hedging. Evergreen examples include shrubs such pyracantha, cotoneaster, escallonia and lavender. Most of these plants are best pruned after flowering or fruiting.
- Pyracantha flowers on the previous year’s growth, so when you prune in the spring after flowering, try not to remove too much of the past two years’ growth. Make sure you wear thick gloves since it has sharp thorns.
- Cotoneaster is a great wildlife hedge, but the variety will dictate when it needs trimming. Cotoneaster franchetii, for example, requires only light pruning after the berries have fallen.
- Escallonia is best pruned after flowering, but you can keep it trim throughout the year with regular cutting, as some varieties grow quite quickly and need to be kept in check.
- Lavender doesn’t break well from old wood; after a few years, some plants may become so leggy and woody that they need replacing. The main pruning is done after flowering in late summer. Cut off the old flower stalks with pruning clippers or hand shears, and then go back over the plants, trimming back to about an inch, leaving some fresh new growth; avoid going into old wood.
- Deciduous flowering hedging plants like Rosa rugosa are pruned in spring, when you simply thin out any leggy growth.
- Forsythia heralds spring and should be pruned by removing stems that have flowered right back to a healthy pair of buds. You can also cut out one in every three stems right back to the ground to encourage basal shoots to grow.
Evergreen hedges. Conifers and Leyland cypresses don’t like to be pruned hard. A hard prune will lead to bare brown stems in the middle of the plant and unsightly patches in places that will inevitably fail to green up.
Because evergreen hedging plants are, by nature, never really properly dormant, don’t prune any of them straight after planting, as you’ll only invite infection into the wounds before the plant has had time to root properly.
- As a plant for a dense hedge, arborvitae (Thuja), also part of the cypress family, is better at being pruned. But, as with the other evergreens, the time to do any cutting is in the spring (March or April) before the first flush of new growth. Some conifers can irritate the skin, so wear long sleeves and gloves when cutting.
- Privet (Ligustrum ovalifolium) can cope with hard pruning. For a new hedge, it’s best to buy bare-root plants since they establish very fast. Prune young plants by a third once they have settled a bit and rooted in, as this will make them bushier at the base.
- Cherry laurel (Prunus laurocerasus) is so tough that you can cut it back as hard as you like. If you want your laurel to flower annually, prune straight after flowering for buds the following year. Portugal laurel (P. lusitanica) is also very forgiving when it comes to being pruned, and it will flower if you leave your trimming until late June.
- To stop a newly planted Leyland cypress (x Cuprocyparis leylandii) hedge from getting out of hand early on, in the first and second year, trim back long side shoots in April and July. Make sure you train the leader (the main dominant stem of the plant) to grow up straight. Keep trimming the side shoots until the plant has reached the desired height. In the spring, once the hedge is the correct height, cut back the leading shoots to about 6 inches below the height you want to achieve, as the new growth will promote a fuller top.
Because evergreen hedging plants are, by nature, never really properly dormant, don’t prune any of them straight after planting, as you’ll only invite infection into the wounds before the plant has had time to root properly.
Variegated and ornamental hedges. There are many varieties of shrubs with variegated foliage that can be used for hedging: Ilex aquifolium ‘Argentea Marginata’, Euonymus fortunei ‘Emerald ’n’ Gold’, Pittosporum tenuifolium ‘Variegatum’ and Cornus alba ‘Elegantissima’ to name a few. When to prune depends on the variety of variegated shrub you have.
Photinia x fraseri ‘Red Robin’, whose new leaves are bright red, falls under the evergreen group of hedging plants, which means it shouldn’t be pruned when it’s dormant, but rather in the growing season. It’s widely used for its ornamental foliage, and regular trimming in spring and summer will help keep it a neat hedge shape. Don’t cut it later than August, however, since any new foliage will be susceptible to frosts.
You can prune a very old Photinia hedge to about 2 feet above the ground around May, and it should soon recover and produce new foliage.
Photinia x fraseri ‘Red Robin’, whose new leaves are bright red, falls under the evergreen group of hedging plants, which means it shouldn’t be pruned when it’s dormant, but rather in the growing season. It’s widely used for its ornamental foliage, and regular trimming in spring and summer will help keep it a neat hedge shape. Don’t cut it later than August, however, since any new foliage will be susceptible to frosts.
You can prune a very old Photinia hedge to about 2 feet above the ground around May, and it should soon recover and produce new foliage.
Tools and safety tips. Spending a bit more on the correct tools for the job is a worthwhile investment. There’s an abundance of quality handheld shears and loppers on the market, as well as battery- and electricity-powered units.
Take time to select the right option for you. Depending on the application required, this should also take weight and comfort into account.
When cutting hedges, protect your ears and eyes. Small pieces of the cut branch can often fly out of the machinery.
If you’re using an electrical hedge trimmer, make sure you have an RCD (residual current device) circuit breaker to protect you in case you cut through the wire. Don’t work for longer than an hour at a time, as you may feel a bit breathless and dizzy, especially if working at a height. It sounds obvious, but do make sure your stepladder is up to the job and never lean it into a hedge.
To help protect your hedge, make sure you have clean, sharp blades to keep it from becoming bruised or stringy as you prune.
When you think you’ve cut your hedge sufficiently on one side, use a spring rake to tap against it. This will make any folded long shoots spring out so that you can catch them in a final pass.
Tell us: Do you have pruning tips to share? Let us know in the Comments.
More
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Got Frost-Damaged Plants? How It Happens, and When and How to Prune
Find pruning tools
Take time to select the right option for you. Depending on the application required, this should also take weight and comfort into account.
When cutting hedges, protect your ears and eyes. Small pieces of the cut branch can often fly out of the machinery.
If you’re using an electrical hedge trimmer, make sure you have an RCD (residual current device) circuit breaker to protect you in case you cut through the wire. Don’t work for longer than an hour at a time, as you may feel a bit breathless and dizzy, especially if working at a height. It sounds obvious, but do make sure your stepladder is up to the job and never lean it into a hedge.
To help protect your hedge, make sure you have clean, sharp blades to keep it from becoming bruised or stringy as you prune.
When you think you’ve cut your hedge sufficiently on one side, use a spring rake to tap against it. This will make any folded long shoots spring out so that you can catch them in a final pass.
Tell us: Do you have pruning tips to share? Let us know in the Comments.
More
How to Prune Your Flowering Shrubs for the Best Blooms
Got Frost-Damaged Plants? How It Happens, and When and How to Prune
Find pruning tools
When you start pruning a large hedge, trim from the bottom to the top. This is very important since it allows more sunlight to reach the bottom of the plants.
The aim is to eventually cut the hedge into an A shape. If you just cut upward in a straight line, the top of the hedge, which always gets more sunlight anyway, will shade the base, giving you a plant that’s weaker at the bottom.
Beech and hornbeam (Carpinus betulus) hedging is best trimmed in August or September, as this will enhance the winter appearance and help keep leaves on the branches for longer. Cut both hedges again in February if you want to keep them looking sharp.
Most people say that it’s best to use pruning clippers or hand shears for this type of hedge, so you don’t tear into the leaf and make it turn brown. Whichever tool you choose, prune back the new long shoots at an angle to two or three leaves from its base.