How to overseed your lawn

Repairing thin or damaged areas of the lawn is fairly straight forward. It's important to keep the newly seeded areas moist until seeds germinate, which can take 7 - 10 days depending on temperature, so daily watering is critical.

• Over-seeding is best done when soil temperature is at least 10°C for germination. Since soil is cooler than air temperature, wait for daytime temperatures of 15°C for best results.
• Give your lawn a thorough raking to remove any leaves and other plant debris. Place the material in your compost bin as long as it is herbicide-free.
• If thatch is thicker than 2 cm (3/4"), consider de-thatching before you over-seed. Thick thatch can impede the flow of water, air and fertilizer (if using) into the soil.
• Spread 1 - 2 cm (1/2" - 3/4") of compost over your lawn to add organic matter and nutrients to your soil. You may use a good quality topsoil instead of compost if desired.
• Seeds can be scattered and pressed right into the compost or topsoil. Premixing the seeds into the compost or topsoil works too. Lightly tamp the area to ensure the seeds have good contact with the growing medium.
• Use a blend of high quality Canada No. 1 grass seed suited to your site (sunny, shady). 
• Add 5% white clover seeds to your lawn seed mixture. This is an excellent way to add nitrogen to your soil. Growing clover at this rate will provide about half of the nitrogen needed to fertilize your lawn. Clover also helps to fill in bare spots, is drought resistant and helps your lawn to resist pests and diseases. 
• When over-seeding water well using a gentle spray. Keep damp (but not soggy) until seeds have germinated. You may have to water more than once a day if the weather is warm or windy.
• Once grasses are 7 - 10 cm high, decrease watering to once every 7 - 10 days at a rate of 2.5 cm of water.