Hedges – especially evergreen ones – are a vital structural part of many gardens. They define the boundary of our space, marking property lines and giving screening from the street, neighbors, and open spaces. Besides the practical benefit of screening, in terms of warmer gardens with less wind, there is value in the sense of enclosure they bring, and the definition they give to the space.
All these things motivate us to put in hedges, but while our intentions and dreams may be good, things don’t always work out the way we thought they would. As you look at your garden, taking stock and wondering if you should make changes, do you look away when your eyes reach the hedges? Are you embarrassed by them? Do they annoy you, thinking of the investment that didn’t pan out, and instead left you with something unsightly?
There are several common faults seen in hedges, and if you have them perhaps something can be done to save the day and turn that unsightly hedge into something attractive. Or maybe not. . . Deciding if your hedge can be saved, or if you should replace it, is the subject of this blog, and we will look at the different things you might see, their causes (so you don’t repeat your mistakes), and what, if anything, can be done. This will give you valuable insights in guiding you to the best next step.
Common Hedge Faults
There are several ‘symptoms’ of bad hedges, so let’s start with diagnosis:
- Doesn’t reach the ground – this is usually because the lower branches have died, since most hedging plants are green to the ground when they are new. Over time the lowest branches first stop growing, and then die. You may have had to cut them off, and perhaps you hoped the trunks would sprout again, but of course they didn’t.
- The lowest parts are thin and sparse – this is the precursor to the first problem and connected to it. Once you start to see little growth down below, which is easy to notice when you are trimming, and don’t need to trim the bottom 3 or 4 feet, then you are heading into a future with a hedge that is bare at the bottom, letting wind, animals and children wander through, and defeating he purpose of your hedge.
- The top is overhanging – as you walk by your hedge, you (or passers-by) collide with the upper parts, because it leans outwards. Besides the nuisance issue, if you live where there is significant snowfall, a broad top is much more likely to collapse under the accumulated weight of snow and destroy the hedge completely.
- There are gaps where branches or plants have died – this can leave ugly spaces, and really make a hedge look bad. This might be caused by disease, and its tempting to blame such outside forces, but in reality plants often die from overcrowding, and if a branch dies and leaves a big hole, there is something wrong with your trimming technique.
Why is this happening to me?
How do these faults come about, and how, with my spanking-new hedge, can I prevent them from happening again? These symptoms can be traced back to two issues – poor planting and poor trimming. Let’s look at each one.
Putting your plants in the ground so you get a reasonable screen quickly, but don’t overcrowd them, is vital to a healthy, working hedge. There is a great temptation to plant those nice young plants almost touching, so that they will become a solid wall almost immediately. Tempting as this is, it is a big mistake. By planting closely together you increase competition between the young plants. They struggle to grow upwards, seeking the light, and two things can happen. First, the lower branches never develop properly, and soon die, leaving the bottom area bare. Secondly, slightly weaker plants become weaker and weaker, until they die, leaving a gap in what is by this point a substantial hedge. You can see how initial spacing errors relate to hedges that are thin or open at the base, and also to hedges that develop gaps.
Correct spacing varies, depending on which species of hedging plant you use. For larger plants like Thuja Green Giant, three feet or more is a good starting point. In theory, with a 12-foot spread, they could go 10 feet apart and still make a solid wall, but that would take time, and they would have to be allowed to grow fat too, creating a hedge that takes up too much room. So 3 or 4 feet is about right, although if you plant a staggered double row (a good idea by the way) then 5 or 6 feet apart in the rows would be spot-on.
Most other problems come from trimming incorrectly, especially allowing the top to become wider than the bottom. It takes discipline to prevent this, as it is natural for a plant to spread outwards as it grows up. You should always be taking more from the top, trying to keep it as thin as possible, when you trim. If you just take the same amount off all over, a wide-top hedge is the result. Keeping the top thin prevents obstruction, allows more light to reach the bottom, and that narrow top is much better at shedding snow and not accumulating so much that it breaks open.
The second issue is trimming upwards only. You should trim in all directions, so that the branches have short, tufted ends, not long strands growing up. If a branch dies – and they do, even on the healthiest hedge – then it only leaves a small hole if you have horizontal branching. That quickly fills in and doesn’t leave the 6-foot gap a long, upward-growing branch will leave. Again, you can see how these errors create the symptoms we began with.
Can I Fix It?
So how many of these problems can be fixed? A lot depends on the age of your hedge, and how advanced the problem is. If you are just seeing the lower part thinning out, and the top is only leaning outwards a little, then some tough trimming, combined with fertilizer and watering, will often bring things back. Remember though, that with the exception of yew trees, conifer evergreens cannot be cut back into bare wood, so there is a limit to how much you can reduce that top. If it is very wide, and an experimental cut shows only bare wood, then it is too late – start planning a replacement.
Gaps can sometimes be successfully filled in. Use the largest plants you can handle, and dig the biggest hole you can. This is difficult if the plants are close together, and you might be better-off removing another plant, just so that you can install a decent replacement. Pay extra attention to that newly-planted bush, and water it well, using liquid fertilizer. It will take a while to develop enough to hold its own against existing plants. Again, of you have lots of gaps, and a generally dilapidated hedge, a complete replacement may be the best long-term option.