Auxins – TrimHedge | Hedge Trimming & Topiary

When I started gardening at home, I inherited a range of hedges in different states. Some of them were quite thin and spindly, so I needed to find ways to encourage them to grow thick. Here's what I learned. Trimming a hedge in a wedge shape that is wider at the bottom will make it grow thicker by enabling more even regrowth. Cut back the hedge at the top to steer growth to the sides of your bushes and use organic fertiliser to encourage the plant's development. Hedge plants are living beings and they respond in many different ways to their environment. Here's a brief run-down of what can cause a hedge to grow thin and how you can address it. Why Does My Hedge Become Thin? All plants are influenced by the weather, their soil and the immediate environment. A hedge becomes thin when it is unable to sustain even growth, which can be caused by lack of nourishment or from invasion by another species. Hedge plants have two hormones that direct their development - auxins and cytokins. Auxins are generated from leaves and buds and, left to their own devices, plants will naturally grow towards the sun, causing the majority of auxins to be produced in those upward areas. Cytokins are produced by the roots and these encourage root growth beneath the ground, which in turn gives the plant a more sustainable lifespan. A bush in hormonal balance will grow outward with new leaves and downwards with new roots, auxins and cytokins working to keep the other in check. However if external factors get in the way the hormones can become unbalanced and this will influence the direction of growth. A plant with lots of new growth at the top may suffer from weaker root growth and is likely to have less new leaf and bud growth towards the base of the plant. . Similarly, a shrub whose roots are growing strong can hamper the amount of growth at the top of the plant, which is one of the reasons why I discourage any pruning of new plants for the first couple of years after planting. How Do I Trim My Hedge To Encourage Growth? To encourage even growth of your hedge plant, trim it at the right time of year - cutting back new growth at the top of the plant in Spring will redirect the growth hormones down to existing areas, leading to a thicker hedge in the Summer. If you want to promote root growth, which I've explained will support the overall good health of your hedge, then trimming in later Autumn/early Winter will encourage the cytokins to work their magic over the cold months. Once the climate warms up, your bushes will focus on growing leaves and buds, and this is where you will want to keep the direction of growth in check. A good trim in early Summer will help even out the naturally occurring run for the sun that all hedges experience. It is important when trimming hedge plants to make sure that the base of the plant is wider than the top. This prevents the lower part of the plant becoming shaded from the sun by the new growth, a classic reason why hedges become thin at the bottom. You will also have a better chance of a more even shape; if you trim a hedge in a cube shape in early Summer, by late Summer you will have a plant that is noticeably wider at the top. Does Pruning My Hedge Help It To Grow? Pruning is an important method for directing the growth of your hedge, as you can precisely cut back foliage and branches that may impede the successful development of a healthy hedge. You may discover that certain areas of your hedge are suffering from their environment and becoming thinner as a consequence. By using secateurs you can focus on specific areas that need attention while leaving the rest of the plant to continue its natural growth. While a hedge trimmer or pair of shears is the best tool for trimming broad areas of the plant, by pruning branches and cutting back woody parts of your hedge, you can force the plant to grow in different directions. and this can lead to thicker healthier bushes. Can I Feed My Hedge To Help It Grow? Feeding your hedge with a balanced nutritional fertiliser will help it to grow - sprinkle it beneath the base of the plant and work it into the soil with a hoe. It is also important to make sure that the plant is well watered. Using mulch on the ground around the hedge plant will also retain moisture and prevent weeds from growing underneath the shrubbery. How Can I Fill In Gaps In My Hedge? Sometimes you will realise that there are gaps in your hedgerow that cannot be closed by encouraging growth. Perhaps the plants have grown too densely and have failed to survive in areas, or maybe an infestation has got into the area and killed off some of the shrub. You may need to replace damaged plants with new versions that will grow as you would like them. If you have to remove the plant, take care to avoid damaging the neighbouring hedge and check that the damage has been limited. Replace a plant in a well-watered hole that has some suitable fertiliser and leave it to grow for a couple of years - this will enable good root growth and allow the plant to find and fill it's place. For more information on how to revive a dying hedge, check out my guide - it's got all the answers so you can save a life! Related Questions How Much Can You Trim Hedges? If your aim is to cut back existing hedge plants to create shape and order and you aren't overwhelmed with leaves and branches, you should not remove more than 25% of the plant at any one time. A cut hedge will grow back most of the time. Can I Hard Prune A Hedge? Hard pruning involves cutting back your hedge plants to between six and twelve inches. This causes the plant to regrow from the ground up and can lead, over time, to a thick, healthy hedge plant. Can Trimming A Bush Kill It? It is possible to over-prune a bush which places the plant under a great deal of stress, sometimes resulting in its demise. I've written a guide to trimming hedges that can help you avoid accidental death in this way.