General gardening topics

How and when to prune Phormiums (New Zealand Flax)

Last updated on April 28th, 2022

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If you have a New Zealand flax evergreen shrub, also known as a Phormium, you know that they can add a great deal of interest to your border garden or landscape and they make excellent centrepieces, some varieties can even be grown in pots and containers. As an evergreen shrub, Phormiums provide you with years of foliage and blooms with very minimal maintenance once the plant is fully established.

One aspect of the minimal maintenance required is pruning. The New Zealand flax plant only really needs doing to remove spent flowers and any leaves that have been damaged by the winter weather.

When to prune your New Zealand flax

The best time to prune your New Zealand flax (Phormium) is going to be in autumn. You can prepare your plant for winter by getting rid of the flower stalks and any brown leaves that have been damaged. This won’t hurt the plant and it will go a long way toward encouraging new growth, especially come spring.

Even though the plant is technically evergreen, the leaves themselves may be damaged by the intense cold they experience in the winter. This is fairly common if you have a very harsh UK winter climate where you live. If they turn brown you will need to remove them in the spring.

How to prune your New Zealand flax

The New England Flax is a robust plant that is well-regarded for its large spiky foliage, but as it grows you need to maintain its shape and size, and you can do this by pruning. The process is fairly simple. The leaves are quite tough and firm so you will need a pair of gloves and a pair of strong, sharp gardening shears. Once you find the leaves that need to be removed because of damage or overgrowth, follow that leaf all the way down to the base of the plant and cut it off at the base.

Just the same as with any plant, always make sure that you regularly sanitise the tools you are using between each use. This will prevent the spread of any disease from one plant in your garden to another. And again, the sharper the tool you are using, the more effective this process is going to be. 

This is a fairly simple process that, when done regularly, will help to keep new growth appearing every spring and improve the overall appearance of your plants.

You can also consider dividing your Phormiums to make new plants or to help reduce their overall size. You should also put a thick layer of mulch around the base during the winter to protect the roots from long periods of frost. This has been something that is known to have killed Phormiums in the past.

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