The shrub in the pot is 18 inches across. The tag says it matures at 6 feet. Almost everyone plants for the pot, because 6 feet of bare mulch between two small plants looks like a mistake, and nobody wants to pay for a hedge that will not look like a hedge until 2030.
So shrub spacing becomes the one garden measurement people knowingly get wrong. Three years later the plants have merged into a solid mass, the bases have gone bare, air cannot move between them, and the only fix is to dig half of them out and start again.
Here is how to space them properly, what you give up when you plant close anyway, and the honest middle ground between the two.
Space by mature width, not by current size
Every spacing decision starts with one number from the plant tag: expected mature width. Find that figure, then work from the percentage that matches the look you want.
- Tight formal hedge: 50 to 75 percent of mature width. The plants deliberately grow into each other and are sheared as one continuous surface.
- Informal hedge or privacy screen: 75 to 100 percent of mature width. Branches touch and overlap slightly, but each plant keeps its own shape.
- Border planting or specimen shrubs: 100 percent or more. Each plant stands clear with space around it and never needs pruning to stay apart.
For a shrub with a 6 foot mature width, that works out as roughly 3 to 4.5 feet for a formal hedge, 4.5 to 6 feet for an informal screen, and 6 feet or more for a border.
Measure centre to centre, from the middle of one planting hole to the middle of the next, not from the edge of one rootball to the edge of the next.
Working numbers by shrub size
If you cannot find a mature width on the tag, these ranges cover most situations for a formal hedge:
- Small shrubs such as dwarf box or low lavender: 12 to 24 inches apart
- Medium shrubs such as most hollies and viburnums: 2 to 4 feet apart
- Large shrubs such as laurel or larger evergreens: 4 to 8 feet apart
Ornamental grasses follow the same logic. A grass that matures at 4 feet across wants 3 to 4 feet between clumps.
Treat these as a fallback. Varieties within the same species differ enormously, and a dwarf cultivar of a large shrub may need a third of the space its parent would.
Distance from fences, walls and the house
The spacing between plants is only half the problem. The other half is what sits behind them.
The rule is the same: plant at least half the mature width away from any solid structure. A shrub that will reach 6 feet across needs its centre at least 3 feet from the fence, or it will grow into the panels, trap moisture against the timber and become impossible to prune on the back side.
That last point is the one people regret. A hedge planted 12 inches off a fence can never be maintained from behind. The back of every plant goes bare and woody, and if a fence panel ever needs replacing you will be working through the shrubs to do it. Our guide to fence post depth and spacing is worth reading before planting along a boundary, because fence repairs are much more likely than people assume.
Near the house, add more. Keep foundation plantings far enough out that mature growth never touches the wall, gutters stay reachable and air can move behind the plants. Trees are a separate and more serious calculation, covered in our guide to how far to plant trees from a house.
Also leave room to walk. If a path runs alongside the planting, mature shrubs will narrow it from both sides, which is why our guide to garden path width recommends building in more width than the path appears to need on day one.
Single row or staggered double row
For most hedges a single row is correct, cheaper and easier to maintain.
A staggered double row is worth considering only when you need a genuinely solid visual or sound barrier and you have the depth for it. The plants sit in two parallel rows, offset so each plant in the back row sits in the gap of the front row.
If you do it, widen the in row spacing rather than keeping single row spacing and adding a second line. A common approach is to space plants within each row at close to full mature width, set the rows roughly half that distance apart, and offset the back row by half the in row spacing. You get density without doubling the crowding.
What you must not do is plant a single row at formal hedge spacing and then add a second row behind it at the same spacing. That is twice the plants in the same ground, and it fails faster than either row would alone.
What crowding actually costs you
Plenty of people plant tight on purpose and accept the consequences. That is a legitimate choice, but it should be an informed one. Here is what you are trading away.
- Airflow and disease. Crowded foliage stays damp. Powdery mildew, leaf spot and root problems all become much more likely, and they spread easily through plants that are touching.
- Bare lower stems. Shrubs shade each other out at the base. You get a green top and a woody, leafless bottom, which is the opposite of a privacy screen.
- Root competition. Plants fight for the same water and nutrients. Growth slows across the whole row, and the weakest ones never catch up.
- No way to replace one. When a plant in a tight row dies, the gap is obvious and the roots either side are already occupying the space. A replacement rarely establishes.
- Permanent pruning. Overplanted shrubs need cutting back every year to stay within their space, and heavy repeated pruning on a shrub that is already stressed is how rows start to thin out.
The cost is not immediate, which is exactly the problem. Years one and two look better than correct spacing. The bill arrives in year four.
The honest middle ground
If you need privacy soon and cannot wait, there are better options than simply planting too close.
Buy larger plants. A more mature shrub at correct spacing closes the gap years faster than a small one planted tight, and it costs less than replacing an overcrowded row later.
Choose a faster growing variety. You are trading speed for a lifetime of more pruning, but it is an honest trade rather than a hidden one.
Plant at the tight end of the correct range. Fifty percent of mature width is dense, closes quickly and is still within sensible spacing. That is different from planting at 25 percent and hoping.
Fill temporarily. Put annuals, grasses or containers in the gaps for the first two seasons and remove them as the shrubs close in. Nothing permanent goes in the space the hedge will need.
Autumn is a good time to plant
Autumn planting suits most shrubs in temperate climates. The soil is still warm from summer while the air has cooled, so the plant puts energy into roots rather than into leaves it has to support through heat.
Rainfall is usually more reliable too, which means less watering during establishment and less risk of losing a plant to a missed week.
The limit is how much time the roots get before the ground freezes. Aim to plant well before that point rather than at the last possible moment, and check the typical first frost date for your own area, because the useful window varies by several weeks across regions.
Once planted, mulch the row but keep the mulch off the stems. Our guide to mulch depth covers how much to use, and the rest of the seasonal jobs are in our guide to fall garden cleanup.
Frequently Asked Questions
How far apart should I plant shrubs for a hedge?
Space them at 50 to 75 percent of their mature width for a tight formal hedge, or 75 to 100 percent for an informal screen where each plant keeps its own shape. For a shrub that matures at 6 feet across, that is roughly 3 to 4.5 feet for a formal hedge.
Do I measure spacing from the edge or the centre of the plant?
From the centre of one planting hole to the centre of the next. Measuring from the edges of the rootballs will put your plants much closer together than intended, because the rootball is far smaller than the mature plant.
How far from a fence should a hedge be planted?
At least half the mature width, so a 6 foot wide shrub sits at least 3 feet from the fence. Closer than that and you cannot prune or maintain the back of the hedge, and you cannot reach the fence if a panel needs replacing.
Can I move shrubs later if I plant them too close?
Sometimes, within the first couple of seasons, while the root systems are still small and separate. After three or four years the roots have interlocked and transplanting a mature shrub rarely succeeds. Plan the spacing properly instead of relying on moving them.
Is a double row better for privacy?
Only if you have the depth for it and widen the spacing within each row. A staggered double row at normal single row spacing is simply twice the crowding, and it thins out faster than one properly spaced row would.
Plant for the plant it becomes
Correct spacing looks wrong on planting day. That is the whole difficulty, and knowing it in advance is most of the solution.
Write the mature width on a stake at each planting position before you dig anything. Stand back and look at the row of stakes rather than the row of small pots. You are judging the hedge you will have in five years, and that one is going to be considerably bigger than the one in your trolley.