Overseeding of an existing lawn is an essential part of annual lawn maintenance. All lawns are affected by the specific growing conditions in different environments in which they exist, their level of use and general weather conditions. As a result, understanding all the basic principles of overseeding and your choice of seed mix will enable you to work with nature toward a greener, healthier and brighter lawn.

Overseeding your lawn will:

• Help infill damaged, bare patches or thin, worn areas and give your lawn a thicker, denser sward.
• Improve the colour of the lawn.
• Reduce weed and moss invasion.

When is the best time to overseed a lawn

The best time to overseed an existing lawn is in spring or autumn, with germination taking 7 to 21 days in ideal conditions.

The Typical daily temperatures need to be in excess of 13ºC for grass seed germination to be successful.

Choosing the right lawn seed

It’s important to choose the right seed for overseeding. First of all, try to work out what grass types you already have in your lawn. You will also need to consider what you use the lawn for heavy traffic (kids), dogs running around, the aspect of the garden, if the soil drains well, as well as the appearance you are trying to achieve.

For a more wear tolerant lawn choose a seed mix containing perennial ryegrass, a blend of some of the most advanced cultivars for excellent appearance and durability, ideal for use in the majority of gardens and perfect for overseeding. It contains both fine and medium-bladed leaf, with outstanding year round colour, that will establish rapidly.

For shady, drier areas or ornamental lawns a pure fescue blend may be more appropriate and will introduce shade and drought tolerant grasses, which have a fine bladed leaf and rich green colour. This type of seed mix is also ideal if you are looking to introduce finer grasses to a ryegrass, utility lawn.

You may also want to select a different seed mix for different areas of your garden or even different areas of the same lawn. For example, a fescue blend for a front lawn and a ryegrass blend for a back garden and a shady part of your lawn will benefit from a higher proportion of fescues in the mix.

How to overseed your lawn

• Mow the lawn to approx 25mm.
• Use a spring tine rake to break up and remove the layer of dead matted grass known as thatch. Dependent on the depth of thatch on a lawn this process may require a powered scarifier, which can be hired from most hire shops. This will help the seed make contact with the soil allowing it to germinate.
• Using a garden fork, spike the lawn to a depth of approx. 150mm at 300mm intervals.
• If your lawn has not been fed in the last 4 months we recommend feeding the lawn before overseeding. The lawn can usually be overseeded 3 to 4 days after applying a general lawn fertiliser, however, you will usually need to wait about 4 weeks after applying a feed, weed & moss killer. (Check the instructions on the product for this.) Pre-seeding fertiliser is ideal and can be applied up to a few days before overseeding.
• Sow the seed evenly across the lawn.
• Lawn Seed should be applied at a rate of 23g per m².
• The seed can be mixed with Lawn topdressing and applied to the lawn jointly. This will save a bit of time and effort working the topdressing and seed into the surface the existing lawn.
• The seeded area must be kept moist, therefore, water your lawn after 2 or 3 days if no rain has fallen.
• Specific bare patches can be reseeded without treating the whole lawn. Apply the same procedure as above, but use sowing rates as for a new lawn 35g per m².
• To protect specific areas from birds consider covering with netting or garden fleece. This should be removed when new shoots start to come through the soil.
• Try to keep traffic on a freshly overseeded lawn to a minimum for 7 to 21 days.
• Raise mowing heights to approximately 50mm for the initial 2 or 3 cuts, then reduce down to 25mm over the next 2 or 3 cuts. Never remove more than a third of the grass blade length at any one time and on new sowings ideally never more than a quarter.