Growing grass in shade: what works, what doesn't and what to do instead

Shade is one of the most common reasons a lawn thins out, and one of the most misunderstood. People feed it, water it, re-turf it and spray it, and the grass under the tree or along the south side of the house keeps getting thinner.

Every lawn grass needs direct sun to grow. Some cope with less than others, but no lawn grass grows well in deep shade. If an area gets less direct sun than your grass needs, no product will fix it. The fixes are more light, a better-suited grass, less wear, smarter care, or accepting that a spot is better as something other than lawn.

How much sun do lawn grasses need?

The Turf Growers Association of WA lists the minimum direct sun for the main warm-season lawn grasses:

These figures are written for Western Australian conditions, and varieties within each grass type differ. Your turf supplier can tell you about the varieties they grow.

“Direct sun” means sunlight falling straight onto the grass, not bright light under a canopy or light reflected off a wall. Dappled shade under a tree counts for less than full sun.

Measure the sun you actually get

Most people overestimate how much sun a shady spot gets. Spend a day finding out.

1. Pick a clear day. Check the area every hour or so from early morning to late afternoon.
2. Note when it’s in full sun, part sun and shade. A phone photo each hour from the same spot makes this easy.
3. Add up the hours of direct sun.
4. Repeat in winter if you can. The sun sits lower in the sky in winter, so shadows from houses, fences and trees are longer, and some areas that get plenty of sun in summer get very little in winter.

Warm-season grasses slow down in winter in most of Australia, so they can cope with less sun then. But a spot that’s shaded for most of the year will struggle.

Two kinds of shade

Shade from buildings and fences

The grass gets less light, but nothing else is competing with it. Caring for it well and choosing the right grass can work if the area still gets enough direct sun.

Shade from trees

Trees cause two problems at once. The canopy blocks light, and the roots take a large share of the water and nutrients. Under trees, a lawn is often short of water even when the rest of the lawn is fine. Fixing the light without fixing the water, or the other way round, rarely works.

Choosing grass for a shaded area

If you’re replanting a shaded area:

• Choose the grass that needs the least sun for your conditions. Of the four main warm-season grasses, the TGAWA lists soft leaf buffalo as needing the least.
• Ask about varieties. Varieties within a grass type differ in shade tolerance. Your turf supplier can tell you which of theirs suits your sun hours.
• Match the rest of the lawn if you can, so the shaded area blends in and the grasses don’t compete at the edges.
• Use the Grass Type Picker to compare options for your climate, sun and wear.

Laying a more shade-tolerant grass helps only if the area gets at least the sun that grass needs. If it doesn’t, the new turf will thin the same way.

Caring for a shaded lawn

Mow higher

Raise the mowing height in shaded areas. More leaf means more surface to capture the light that does reach the grass. Never take off more than a third of the leaf at once.

Cut down traffic

Shaded grass grows more slowly, so it recovers from wear more slowly. Shady spots are also where people tend to sit in summer.

• Move outdoor furniture, play equipment and dog beds around so wear is spread out.
• Put stepping stones along regular paths.
• Keep heavy use off shaded lawn while it’s recovering.

Water deeply under trees

• Water slowly and deeply, so water reaches the grass roots and not just the tree roots near the surface.
• Check with a screwdriver a few hours after watering. It should push in easily.
• Watch for dry patches. Soil under trees often dries out and turns water-repellent; a wetting agent can help.
• Don’t overwater shade from buildings. Without tree roots competing, shaded soil dries more slowly than sunny lawn.

Feed lightly

Shaded grass grows more slowly, so it needs less fertiliser than a lawn in full sun. Feed at the label rate while the lawn is actively growing, and don’t add extra to try to force growth. Under trees, roots compete for nutrients, so a light feed may help the grass hold on.

Watch for disease

Shaded lawns stay damp for longer, which suits some fungal diseases. Brown patch, for example, appears in mild, humid weather. Water early in the morning so leaves dry during the day, improve air flow by pruning low branches, and avoid watering in the evening.

Keep leaves off

Fallen leaves block what little light the grass gets. Rake or blow them off regularly, especially in autumn.

Letting in more light

The most effective fix for a shaded lawn is usually more light.

• Raise the canopy. Removing lower branches lets in more angled morning and afternoon sun.
• Thin the canopy. Selective pruning lets more light through without removing the tree.
• Trim hedges and shrubs along the lawn’s edges.
• Consider fences and screens. A more open fence or screen lets more light through than a solid one.

For anything beyond small branches, use a qualified arborist. Councils can protect trees, including trees on private land, so check your council’s rules before pruning or removing a tree. Never remove a tree only to grow lawn without thinking about the shade and cooling it provides.

Sorting out tree roots

• Don’t pile soil over tree roots to bury them under new turf. It can harm the tree, and the roots usually come back to the surface.
• Don’t cut large roots to make room for lawn. It can harm or destabilise the tree.
• Use mulch around the base of the tree, out to where grass can grow well.

Repairing thin patches in shade

Thin patches in shade fill in slowly, because the grass around them grows slowly too.

1. Fix the cause first: light, water, traffic or tree roots.
2. Wait for the growing season. Repairs in late spring and early summer, when warm-season grass is growing strongly, recover fastest.
3. Core compacted areas while the grass is actively growing, so water and air reach the roots.
4. Topdress lightly so the leaves still show, and let the runners grow across.
5. Patch with turf of the same grass if the bare area is large, and keep traffic off until it roots.

Shade through the year

When a spot is better as something else

Sometimes the answer is to stop trying to grow lawn. In deep shade, or under trees with dense canopies and shallow roots, consider:

• mulch, which suits trees and keeps the area tidy;
• pavers or stepping stones, for areas that get walked on;
• shade-loving groundcovers or garden beds;
• a seating area, where people already sit in the shade.

Reshape the lawn so it ends where the sun does. A clean edge between lawn and mulch looks better than a thin, patchy lawn that’s always struggling.

A worked example

A buffalo lawn is thinning under a large tree in the back yard and along the south side of the house.

• The sun map shows the area under the tree gets about 2 hours of direct sun in summer and less in winter. The south side gets about 4 hours in summer but almost none in winter.
• Under the tree: even buffalo needs at least 4 hours. The owner has the canopy raised by an arborist, and mulches the area closest to the trunk, where shade is deepest, with a curved edge to the lawn.
• The south side: the owner raises the mowing height, puts stepping stones along the path to the side gate, and feeds lightly in spring and summer. The grass thins in winter but recovers in the growing season.

Common mistakes

• Feeding a shaded lawn more to make up for the shade.
• Re-turfing every year without fixing the light.
• Mowing shaded grass as short as sunny lawn.
• Watering shade from buildings as much as sunny lawn.
• Burying tree roots under soil and turf.
• Pruning or removing trees without checking council rules.

Log it

Record your sun map in your Lawn Journal, with the date, along with any changes you make: pruning, mowing height, new turf. Over a year, you’ll see whether the changes are working, and whether a spot is better left to mulch.