Overseeding, Ph levels and dethatching your lawn

Overseeding

Overseeding is a process in which you add seed over your existing lawn to help fill in thin patches and crowd out undesirable weeds. Spring and early autumn are generally the best times to do this.

Overseeding can be time-consuming if you have a large lawn but it is not difficult and the results are well worth the effort, dramatically improving the health and appearance of your lawn. Another advantage is the reduction in week invasion thus minimising the use of chemicals.

Preparation is key to successful overseeding:

• The first thing to do is remove weeds from the area. If you need to spray, do so at least a week before sowing so your new grass is not affected by the chemicals. 
• Next, ensure you have mown your lawn and raked up any debris to ensure the new seed can make contact with the soil. 
• You may need to ‘dethatch’ your lawn at this point. Thatch is a layer of mostly dead organic matter on top of the soil that prevent seeds contacting the soil. 
• Aerate the lawn to eliminate any compaction and you may wish to add some nutrients at this point to help the seedlings thrive. 
• Distribute your good-quality seed depending using manufacturers’ instructions and rake lightly to ensure contact with the soil. 
• Keep your new seed moist – a good tip is to do this is when rain is forecast - and once sprouted follow your normal watering schedule.
• It is recommended waiting until your new grass is at least 3cm tall before you mow it.

Soil pH and Lawn

Healthy soil provides the foundation for a good lawn. This is often overlooked but is critically important in lawn seeding and maintenance - you could be doing all the right things for your lawn but if the soil is hostile it won’t thrive, and you could be wasting money on the wrong products. The proper balance of nutrients, an optimum moisture level and correct acidity or alkalinity all contribute to a lush and thriving lawn.

The pH of your soil will tell you how acidic or alkaline it is. A high pH above 7.5 is too alkaline and indicates it is probably deficient in nutrients. A low pH below 6.5 is too acidic and might mean you are using the wrong combination or too much fertiliser. An alkaline soil will need more sulphur while lime can be used to correct an acidic soil.

Regular soil tests via ‘Lawns Club’ will include a pH reading and we will recommend the appropriate fertilisers and provide instructions on how to correct or maintain your soil.

Dethatching your lawn

Thatch occurs naturally in all lawns and happens when an organic layer of stems and leaves, both living and dead, intertwine and form a layer between the growing grass and the soil line. If the layer of thatch is over 1-1.5cm, water, air and nutrients cannot make their way through the layer and your lawn will suffer. Thatch can lead to a shallow-rooted lawn which can dry out quickly and result in spongy lawn easily scalped when you mow. Shallow-roots also make the lawn more prone to insect attack and disease. So, a thick layer of thatch should be avoided.

Certain grasses and lawn management affect how quickly thatch develops. Common causes are:

• Frequent and shallow watering causing debris to sit near the surface
• Overly lush growth caused by over fertilisation and watering
• Leaving the grass too long, mowing infrequently and too high
• Over-use of pesticides and fungicides that kill or slow the growth of microbes and perhaps even earthworms that would normally break thatch down
• Compacted or heavy clay soil that is poorly aerated
• Soil pH 

Generally every lawn should be dethatched at least once a year. The most common times to dethatch your lawn are late summer, early autumn or spring and it is essential that the weather conditions are warm to promote rapid and healthy grass growth after dethatching. There are three ways to tell if your lawn need may need dethatching:

• By touch – if your lawn is bouncy underfoot.
• By sight – if you can’t see the soil between the blades of grass
• Measurement – if you dig up a small section of the lawn and see a layer of thatch that is sitting on top of the soil. If it’s 1.5cm or greater it is time to dethatch your lawn.

Dethatching your lawn means cutting through the thatch then removing the debris. A specialized thatching rake could work on a smaller lawn, but for a larger lawn power equipment might be required such as a scarifier. It can leave your lawn looking like a mess but it won’t last for long. Collect up all the debris with a regular rake (you can pop it into your compost bin) then spread a thin layer of compost over your lawn and give it a good watering. If you find you have areas that look bare, lay some seed or ‘overseed’ the area to thicken up the grass. Before too long your lawn will look healthy and lush.