Caring for your Leylandii hedge

Leylandii topiary in the shape of a viaduct at Newtownards, Portaferry Road, Mount Stewart, Northern Irelandcredit

Once you’ve planted your new hedge, your work has only just started! Here’s the low-down on helping your Leylandii trees to grow and thrive.

Leylandii hedge giving privacy around a swimming poolcredit

Keep your trees well watered

You need to make sure the trees get enough water to thrive and that their roots don’t dry out.

If you’re planting them between November and February, they’ll need less water (or none at all if it’s rainy) – compared to if they were planted in spring and summer. If you buy pot-grown Leyland cypress trees from thetreecenter.com you can plant them from March to October just fine, but make sure you water them regularly. Once they’ve gone through one growing season, their roots will have extended enough so that they won’t need additional help from your garden hose.

Long, tall Leylandii hedge with a large urn to give structure and proportioncredit

Here’s how you water them

You should check if your trees need watering by putting a finger into the root ball – or the soil next to the root ball – and judging its dampness. It should be moist, but not waterlogged. You should do this every two or three days throughout the first growing season.

You’ll probably find that new Leylandii need a good watering once or twice weekly, but obviously this depends on your weather and soil type. If you’re planning to go on holiday, use an automated sprinkler or ask a friend or neighbour to water them while you’re away.

Hose the soil around the root ball until the water starts to run off, then move along to the next tree. Wait for the water to sink in before repeating this process three or four times.

You might imagine that rain is enough to keep your trees watered, but often summer rain isn’t heavy enough, so it would be a good idea to invest in a rain gauge. The average Leylandii needs around a ¼-inch of rain to provide it with enough water for three days during the summer months. If you’re not getting that from the sky, you’ll need to intervene! Step in before the foliage starts to wilt and before the roots dry out.

Giant Leylandii hedgecredit

Drought symptoms

When Leylandii get too dry or too wet, you’ll see the leaves turn yellow, then brown. This starts at the bottom of the plant near the trunk, before spreading.

As you’d imagine, drought symptoms are most often caused by the lack of water, but similar symptoms can also be down to too much water. Don’t leave an automatic sprinkler on for too long, and if you’re planting in heavy clay, break it up with a garden fork or shovel so excess water can drain downwards and sideways. Otherwise, the roots will rot and this means they stop working, leading to water not reaching the foliage.

Trimming a Leylandii hedgecredit

How to establish and maintain your hedge

You can begin to trim your trees as soon as you’ve planted them – lop off any branches that are too high or long and this will encourage shoots to grow within your ideal shape, thickening the hedge. When the tops of the trees get to about six inches from your desired height, trim the tops, which will thicken out the width.

Once your hedge is established, you only need to trim once a year.

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