Shaded lawns have different requirements from lawns that are grown in full sunlight. A shaded lawn may be in full sun for part of the day and full shade for the rest of the day or it may receive filtered sunlight that passes through the canopy of the trees and leaves.
Stress effects of shade on the lawn
Shaded lawns are subject to more stress than lawns that are grown in full sunlight. Reduced sunlight can be caused by the shading effect of trees, shrubs and buildings. Fallen leaves can also shade a lawn and prevent sunlight reaching the grass blades.
The first stress is a result of less sunlight, this means that the amount of photosynthesis that takes place in the grass is greatly reduced. Photosynthesis uses the energy of sunlight to produce ‘food’ for the grass so that it can grow. In shaded lawns the rate of growth is therefore slower when compared to sunny aspect lawns.
A side effect of lack of sunlight is that it results in the lawn being more subject to moss infestation as the turf is damper due to the lack of the suns drying effect. Moss thrives in damp conditions.
The other main stresses on the lawn are caused by the roots of trees and shrubs which overhang the lawn. The roots of these trees and shrubs compete with the grass for both water and nutrients. Large trees can lose hundreds of litres of water a day by evaporation through their leaves. They replace this water by drawing it up from the soil and through their roots. The trees root system can deprive the grass roots from being able to take up sufficient water.
Trees can also prevent rain from reaching the lawn and soil as it can be intercepted by their leaves and branches and then lost through evaporation. Trees and shrubs also take up nutrients from the soil and so the lawn suffers because there are fewer nutrients that are available to the grass roots.
The net effect of these extra stresses on the shaded lawn mean that it has slower growth rates, is more susceptible to drought and requires a longer recovery and regrowth period after mowing.
All lawns need some degree of sunlight for sufficient growth and if this level of sunlight is not available then the lawn will not grow properly and it will be impossible to establish/maintain the lawn. If this is the case then an alternative ground cover plant should be considered along with other alternatives such as bark mulch, synthetic turf and gravel.
Actions to counteract the stresses faced by a shaded lawn
Choose suitable grass type(s)
Certain grasses are much more shade tolerant than others. Fescues are commonly used on shaded lawns, especially red a chewing fescue.
Water thoroughly (roughly once a week in the hottest parts of the year).
Mow higher than lawns that receive full sunshine
Only remove 1/3 of the grass height when mowing
Prune trees and shrubs – reducing the shade level
– Remove all tree branches that occur below 8 feet up the trunk
– Thin the density of the trees canopy by selective pruning to enable more light to filter through the gaps in the canopy
Remove fallen tree and shrub leaves by using a light rake. Heavy raking can pull out some shallow rooting shade tolerant grasses such as fine leaved fescues.
Lawn care summary for shaded lawns
- Routinely prune trees and bushes to reduce shade density
- Set your lawn mower blades higher and mow more often
- Water the lawn more often in warm seasons
- Feed more often but with half the amount
- Promptly remove leaves and other plant debris that fall / collect on the lawn