The Tree Center

Spacing Hedges – Let’s Get it Right

September 21, 2020

Written by Dave G.

Hedges are important components in just about every garden. In cities and suburbs they give privacy and a calm background to your garden, screening out neighbors, traffic noise, and unsightly views. In rural areas they provide wind protection and that sense of enclosure that is often needed when creating a garden inside a larger area. While hedges are often planted around the perimeter of a garden, to define its overall form, they are also incredibly valuable as internal dividers, especially in a large garden, where they can separate work areas from ornamental sections, and enclose the vegetable and fruit areas from lawns and play sections. Low hedges can border drives and pathways, and although they are often thought of as straight and formal, they can also curve and flow gracefully for less formal looks, and be used playfully too, with undulating tops, or even trimmed into exotic forms, like the 100-foot dragon hedge shown at the top.

Correct Spacing is Vital

Whatever the form or function of your hedge, and whether you choose evergreen or deciduous plants, spacing out those plants correctly for your needs is vital. Too close and you will have an overgrown mess that will quickly thin out at the bottom – besides costing you more than it should to plant. Too far apart and that smooth, flat surface you want could be decades away. Hedges should be the first thing you install in your garden, once you have decided on the basic layout, so let’s take a detailed look at this issue, which always creates uncertainty for new gardeners.

One Row or Two?

There are two basic layout patterns used for hedge planting. The most common and straightforward is to use a single row of plants, evenly spaced along a line. Remember when doing this that the first and last plant should be half the spacing distance away from where you want the hedge to end, which could be in the open, with a trimmed end, or up against a wall or fence. A common mistake is to plant the first tree right at the end, forgetting to allow room for foliage to develop and make a smooth, green edge. Always use a tight cord to make the line, and space out all the plants before you start putting them in. That way, any slight errors in your measurements can be adjusted for by moving plants around a little until you are satisfied that they are all evenly spaced. If the spacing you use is relatively close, then digging a trench for planting will make spacing much easier and give your new plants a great area of dug soil to spread out into as well.

If you want a really dense hedge, with maximum sound buffering and wind resistance, then a double row is the way to go. The rows are staggered – that is, each plant in one row is in the space between the plants in the other row – a kind of zigzag pattern. You do of course need more width, so this option is rarely useful in a smaller garden, but for a big windbreak hedge it will give you quick results and a solid fill.

Spacing Distances for Single Rows

The distance apart you space your plants depends on two factors – final height and the natural width of your chosen plant. For low hedges you obviously need the plants closer together, and for something like a 12-inch boxwood hedge, planting as close as 8 inches apart is normal. For that you need a supply of small plants, but most hedges can be successfully created out of larger material, of course. As a general rule, with smaller plants and hedges under 5 feet tall, the spacing should be about two-thirds of the intended finished height of your hedge. So, if you want a 3-foot hedge, space the plants no more than 2 feet apart. As well, when planting low hedges, choose rounded or bushy varieties of the plant, not slender upright versions. This sounds counter-intuitive but keeping low hedges bushy all the way to the ground is often an issue, so you want plants that push shoots out sideways, not straight up.

Consider too the final height of the plant you are choosing, and its growth rate. It is easy to see that a plant that normally grows to no more than 3 feet will never make a 5-foot hedge. However, a plant listed as reaching 10 feet, but that only grows a few inches a year, like some boxwoods, is going to take a couple of decades to reach that 10 feet, which is rarely a practical time-frame when growing hedges.

For larger hedges the key factor is the natural width of the plant. Try to find its height and width after 10 years of growth. Will it be tall enough by then for the hedge-height you want? Look at the width. That represents the growth on both sides of the trunk, so its sideways reach towards another plant is half that. Two plants side-by-side will, if spaced that width apart, touch after 10 years. However close planting makes bushes grow upwards towards the light, so they will be slimmer. A good rule is to space your plants at half that ‘10-year width’ apart. So, plants that will be 6 feet wide in 10 years should be spaced 3 feet apart in the row.

Spacing Distances for Double Rows

A double row isn’t just two single rows, staggered. That will be too crowded, and the plants will grow tall and spindly. Calculate the spacing for a single row, and use that as the spacing between the two rows. Add 50% to that single-row spacing, and that is the distance apart for the plants in the row. If you do the math – we won’t bore you with it, but remember that Pythagoras guy? – that creates a situation where the spacing on the diagonal is 25% more than the spacing for a single row. That gives us a good alternative way to lay out the plants, using a stick cut to the single row spacing plus a quarter of that spacing. Place it at 45 degrees to the direction you are going with your hedge.

To Summarize

All that sounds a bit complex, but it isn’t really. Let’s summarize:

See, that was easy!