It is best to spray the existing grass with a non-selective weed killer, such as glyphosate (ask chemical supplier for trade names). It is absorbed by the leaves and translocated to the roots but does not have a residual effect in the soil. This type of herbicide kills anything green so be careful when you spray. (It does not have a residual effect in the soil).

Wait for a week or two for the grass to go completely brown before removing. You may need to spray more than once.

Remove the dead grass (mow on lowest setting and then dig out the rest).

Bunch grasses do not heal themselves after damage has occurred.

Damage that may occur would include:

Leaf and/or plant scorching caused by the urine of dogs. Bitches urine seems to have a harsher effect.
Heavy traffic in specific areas
The tree canopy is too dense. Call an Arborist to thin out the tree canopy.
Mowing the lawn at an incorrect mowing height. When the lawn is thinned out interseeding is the only way to correct it.
The damage may cause the grass plant (bunch) to die. This would cause the lawn to become spares or patchy looking.

Inter-seeding patches in the lawn
Where a part of the lawn is damaged, repair it as follows:

1. Remove the damaged or dead grass
2. Lightly till the soil to relieve compaction (if any)
3. Level the area to be at the same levels as the rest of the lawn
4. Sow in the seed and keep the soil moist until germination is complete
5. Mow the area as you normally would
6. Continue with normal lawn care

In the Shade

When grass is growing in the shade it is essential that the cutting height be lifted to about 6cm.

This is because the plant needs an increased leaf area to intercept as much light as possible in order to photosynthesise adequately. Remember that photosynthesis is the process by which the plant converts sunlight energy into plant energy. It is the ONLY way the plant can synthesise (make) food. The plant is programmed to maximize its leaf area so it naturally assumes a more upright growth habit to intercept more light.

Fertiliser is important for allowing the plant to function properly (rather like vitamins being important for humans!) but nothing can take the place of real food.

A plant growing in the shade also manufactures extra chloroplasts (those organelles in the cells containing Chlorophyll that catch the sunlight. It is the extra chlorophyll (green pigment) in the cells that make a plant growing in the shade greener than those growing in a sunnier location.

MOWING TOO SHORT CANCELS OUT THE PLANTS ABILITY TO ADAPT TO SHADE CONDITIONS.

There is a limit as to how much shade even a shade grass can tolerate so you may need to call in an arborist to thin out your tree a bit to allow more light in.

In the Sun
You can mow shorter in the sun, provided that you remember the 1/3 rule*. Assuming you don’t want to mow more than once a week, you shouldn’t mow shorter than 4 cm. You could mow down to 2 cm but than you will have to mow twice a week in the growing season. This applies to Kikuyu too, which explains why it often deteriorates.

Another reason for keeping the cutting height on the long side is that longer blades support deeper roots.

What Type of Mower?
A rotary mower works best because it doesn’t flatten the grass while mowing, and many of them can be adjusted to mow at 6 cm. If yours can’t be adjusted to mow that long then you will have to change your mower.

The 1/3 Rule for ALL GRASSES
Never remove more than 1/3 of the leaf length at a time.