Sometimes things in the garden don’t work out as we thought they would. With hedges, that vision of a lush green wall framing our garden and bringing privacy doesn’t materialize – instead we have poor growth, gaps, thinning out, and other issues that arise. We want to fix them – and also understand where we went wrong. Some fixes are easy, others perhaps not, so this can also be a cautionary tale on how to avoid things going wrong.

‘My hedge looks pale and thin’

Instead of thick, bright-green foliage on your Thuja Green Giant, or other evergreens, they are growing slowly, and the leaves look pale, perhaps with some of the older pieces looking yellow. There are two possible reasons for this – lack of nutrients or lack of water – or both. Evergreens need plenty of nitrogen, and if your soil is sandy and lacking in organic material, then there will not be enough available. As well, if your plants have been dry for some time, perhaps due to drought, or because you haven’t watered them, they are not absorbing water. The pathway for nutrients is via water, so if there is very little water uptake, even if you have fertilized, and have rich soil, the minerals are not making their way into your plants – which are in survival mode, trying to cope with dryness by going dormant.

This one is an easy fix. First, establish a regular watering pattern. This will be a lot easier if you install a simple ‘leaky pipe’ trickle hose along the base of your hedge. Wind it in and out between the plants, so you cover the area well. Attach this to a regular hosepipe, and let it run for several hours, so that the water makes its way down to the roots. To restore your hedge, do this weekly for a couple of months, and then it will only be needed when the soil is dry. If this is a newly-planted hedge, then you should keep up the weekly watering into the fall on a weekly schedule. An easy way to do this chore automatically is to attach a timer to the outdoor faucet. These are inexpensive, and can be programmed to come on automatically, without the expensive of a full irrigation system.

If the problem is poor soil, then the best fix is to improve your soil when planting. Add plenty of rich organic material, like compost or rotted manures, when digging the area over before planting. If you didn’t do this, there is still hope. Start with concentrated fertilizer – it could be something organic like fish meal or fish emulsion, or alfalfa pellets, or a synthetic fertilizer. The quickest fix is with a liquid fertilizer – look for a high first number, perhaps around 20, in the fertilizer formula. This should be watered thoroughly into the ground over the root area, and you can also spray it at half-strength directly onto the foliage. Repeat 2 weeks later, and again a month later. You should see a big improvement. Once you have restored growth, start using fertilizer regularly, in spring and through the summer. Once your plants are healthy again you can switch to a granular fertilizer, which is much easier to apply. There are also slow-release formulations that only need one application a year – an even bigger time saver.

‘The bottom part of my hedge is looking thin’

Once a hedge has grown to its full size, the lower parts can weaken and thin out. In extreme cases the whole bottom section for several feet may die, leaving your hedge on bare trunks. Yet that lower part is usually where we want it to be thick and green. What to do?

This problem is most often seen on the north-facing side of a hedge, and there are two possible causes. It might be you have planted shrubs in front, and as they grow they are making a lot of shade on the bottom of your hedge. That shade will reduce growth, and it may kill the lower branches. Evergreens like Thuja Green Giant need sun or bright light, and in the shade of shrubs, especially other evergreens, they will abandon their lower branches, and put their energy into the upper growth – which is not what we want in a hedge. The fix for this is simple – trim those plants in front, if necessary removing some – you can transplant them somewhere else in your garden – to let the light in. it is best to leave a pathway at least 3 feet wide between the outer branches of other plants and a hedge.

The second reason could be poor trimming, specifically, letting the top growth become too wide. Look at your hedge from the end. Is the top wider than the bottom? If it is, then the upper part will draw all the energy, leaving the lower branches to starve and weaken. If you catch this problem while the lower parts are still reasonably healthy you can turn it around. Start trimming more from the top, in stages, until you have a slight inward slope on the face of your hedge. Remember that you can’t trim evergreens back to bare branches and expect then to re-shoot. With a few exceptions, like yew trees, they won’t. So you need to cut back in stages, always leaving some green. If the problem is not too extreme you will be able to reverse this error. Of course if you are starting a new hedge, don’t let it happen in the first place, and always lean the face of the hedge backwards a little, to let light to the bottom, and inhibit the upper growth from taking over.

Sadly, once that lower part is dead, you won’t be able to bring it back. Planting small plants along the bottom sometimes works, but it often doesn’t. It is almost always better in the long run to start again with a new hedge.

‘Every spring my hedge is brown’

There are three reasons this might happen. The first and most obvious is that you have chosen plants not hardy enough for your location. Thuja Green Giant is hardy to zone 5, but not colder. Other evergreens will take colder conditions, while others need more warmth. Always match your choice of plants to your location.

The second possible reason is salt damage. If your hedge is along a roadway that is salted, then drifting salt can burn the foliage. Thuja Green Giant is tolerant of some salt spray, but other evergreens for hedges are not. The best solution, if this is a regular problem, is to erect a burlap screen a couple of feet in front of your hedge, to catch the spray. Don’t let it touch the hedge, otherwise the salt will just sit there, and the damage can be worse.

The third reason is lack of moisture at the roots. If neither of those first two reasons seems to be the problem, then soak your hedge well shortly before the soil begins to freeze up. Apply a mulch over the roots as well. This will keep the ground from freezing so hard, and your hedge plants will not desiccate in the cold, dry, winter winds.