The best time to sow grass seed is between early April and early September, however you must firstly carry out some preparation. Ideally sometime between March and August you must “burn off” any unwanted growth. Achieve this by spraying all weedy soil areas on a dry day with a herbicide containing the active ingredient Glyphosate. Apply according to the manufacturers instructions and heed safety warnings.
Grading the site
A minimum of 1 month must elapse before you start to grade or level the site, this will allow the spray to reach the roots of weeds such as docks and dandelions. Ensure nothing but light rainfall occurs when you are carrying out soil movement and grading whether it be by hand or machine. This will prevent creating a pan in the soil (a layer of smeared soil or subsoil that water cannot drain through). You must grade the site to an acceptable level without bringing subsoil to the surface; subsoil on the surface has ruined many the new lawns by causing hungry looking brown patches. When grading your soil remove any half buried timber and old tree roots as they will lead to toad stools in the established lawn. Also remove any concrete blocks and large stones; basically remove any debris bigger than your fist.
Fallow before final cultivation
Leave the graded site to settle and regrow any dormant weeds for at least a month then spray the weed growth again with a Glyphosate based herbicide. For the final cultivation give the soil a shallow rotovate or lightly dig it over with a garden fork whilst breaking clods with the back of the fork. Rake to an acceptable level whilst removing all surface debris down to the size of a 1 euro coin including weed stems and roots. The soil should have a nice fine tilth like the texture of cake crumbs; it should not be fine like powder as this will prevent seed germination.
Seed sowing secrets
The ideal situation would be to sow the seed before you get the next heavy shower of rain as at that stage you will begin to loose the soil tilth. You will need approx 40 to 50g of seed per square metre, which can be broadcast by hand or use a wheeled spreader Divide the seed into 2 lots and spread half the seed whilst walking up and down, with the other half being spread whilst walking left and right across the lawn When spreading any seed avoid spreading onto drives, patios and beds. Lightly rake the seed into the soil with a sprung rake, do not drive it in or bury it. Follow this by lightly rolling the area with a half-filled water roller; the idea is to get firm seed and soil contact to ensure germination. Have some extra soil and seed to hand as a hollow or two may show up when rolling, you can then top up the soil and give it a shake of seed. Depending on the weather conditions your seedlings will begin to appear within 2 to 3 weeks.
