Thatch is dead grass and plant material that nature has not been able to break down. Instead, it has formed an impenetrable layer below the grass.

When the thatch layer exceeds .2 inches, the water permeability of the soil decreases, the grass roots grow closer to the surface and the root mass and the oxygen exchange decreases.

As a result, the grass becomes less durable and can no longer withstand the foot traffic it once could. In addition, the risk of disease increases dramatically and some grass varieties cannot survive.

Thatch forms for a number of reasons, for example:
• The use of modern, lab-created grass varieties
• The use of fertilizer with high acidity
• Over-fertilization

WHEN SHOULD YOU DETHATCH YOUR LAWN?
It is a good idea to dethatch when the grass is growing well, preferably in late spring or early autumn. Avoid dethatching in early spring or during dry periods, as you may stress your lawn.

WAYS OF DECREASING THE THATCH LAYER
To remove the thatch layer you can use a variety of tools. Dethatching machines with flail blades are a good tool. For more sensitive grasses, a dethatching machine with spring tines is recommended.

You can borrow, rent or purchase a scarifying machine, or you can scarify your lawn by hand using a spring-tined rake. Draw the rake over the lawn in short sweeps, digging the tines into the top level of the soil. Work in one direction across the lawn and then again at right angles to your initial sweep.

Scarifying machines are essential for larger lawns (unless you feel you need the work-out!) and they will usually pick up the thatch for you. Once you have completed the scarifying process, mow the lawn, collecting the clippings, to remove the thatch and even up its appearance.

If you have a great deal of moss in the lawn, you may wish to consider applying a moss killer. If you garden organically and have a problem with moss, it's usually because of inadequate sun or poor drainage. Consider the viability of lawns in shaded or damp ground.

OTHER BENEFITS OF DETHATCHING
A dethatching machine can also be used to cut the lateral roots of the grass and to fight broadleaf weeds. This is most effectively done with a delta blade.

COMPACTED SOIL
Compacted soil makes it difficult for plants such as grass to develop. Compaction limits the movement of water through the soil and the ability of the roots to grow. The water surplus that develops creates a lack of oxygen in the ground, which is also not good for the plants.

Compaction damage can affect new or existing lawns. Some causes are: constant vibrations from traffic in urban environments, the use of heavy vehicles when laying the lawn or heavy foot traffic on the lawn.

HOW CAN THE GROUND BE LOOSENED UP?
Loosening up established vegetation areas such as grass areas is done by aeration. This is done with special spike or hollow tine aerators. A spike aerator simply punches a hole in the ground. A hollow tine aerator stamps out cylindrical holes in the earth, approximately 3 inches deep and brings the plug to the surface of the earth.

WHAT ARE THE ADVANTAGES OF AERATING?
• Stronger root growth
• Increased water permeability
• The grass can better withstand dry weather conditions
• Better root hydration
• The need for weed killer is reduced

WHEN SHOULD YOU AERATE?
The grass should always be growing well before you start deep aeration. You should never aerate when the grass is not growing well or when it is stressed, such as during a dry period.

WHEN AND HOW OFTEN SHOULD YOU FERTILIZE?
When to fertilize the grass, and how much fertilizer to use, depends completely on what the grass is used for and its location. Areas that are not subject to intensive wear should only be fertilized when there were signs of poor growth during the previous year. Heavily worn areas require regular fertilization.

If the grass only requires fertilizing once, it is best to do it in spring. In the case of a frequently used surface, it should be fertilized first in spring when the grass needs nutrients most, then in summer to support strong growth and finally in late autumn to give the grass a supply of energy for the following year.

HOW CAN YOU DECREASE THE RISK OF DEHYDRATION?
If the grass is healthy and dark green, very little water is required. If you live in a dry region, or are experiencing drought, you should water enough so that your grass maintains a healthy green color.

You can decrease the risk of dehydration by increasing the cutting height, by always cutting with sharp blades, by aerating the grass and by mulching your lawn.

A sign of dehydration is the grass turning light green, and then starting to turn yellow.

OVER-SEEDING A NEW LAWN
Over-seeding is when you add seed to an existing lawn to thicken and improve the appearance of a thin or patchy lawn, or to give winter color to a dormant southern lawn.

Winter damage, dehydration, or water damage due to poor drainage, (a result of a compacted topsoil layer), are some possible causes of damaged grass in need of renovation.

If less than 50% of the grass in an area is damaged over-seeding is preferable.
If more than 50% is damaged, either turfing or new seeding is recommended.

Turf is grass that has been cultivated.

OVER-SEEDING
When you over-seed, it is recommend that you law it down in a straight line the first time and cross it at a 45° angle the second time. This is to cover the areas as efficiently as possible and not to leave any unsown areas.

Remove old grass, including all root masses. If the weather is dry, the ground has to be broken down to a depth of approximately 8 inches (to ensure contact and water permeability). Remove any stones and level out any irregularities in the surface. Just before laying the new turf, roll the ground with a hand roller to get a firm, even surface.

HOW DO YOU LAY TURF?
Turf is laid in straight rows, edge to edge. In the joints you can put a mixture of the soil from the ground and dressing sand. The grass surface is then rolled, perpindicular to how it was laid.

Right after laying the turf, the entire area should be watered. Two days after laying, the area should be rolled again with a hand roller to maintain contact between the turf and the soil underneath.

Normally the grass has to be watered daily for the first three weeks.

WHEN SHOULD YOU FIRST MOW TURF?
When cutting and laying turf, it is important that it is growing well and that the weather is not too dry. Depending on what time of year the turf is laid and the temperature differences at the time, the grass will grow at different rates. During spring and summer the grass will have taken root enough after three weeks to be used and walked on. That is also when the grass is mowed for the first time.