If a lawn is dotted with weeds and you want to avoid herbicides, here's how you can prioritise your mowing height, overseeding, and soil improvement for best results:
Mowing Height
If you want your grass to be strong and healthy, so that it can outcompete weeds easily, prioritise mowing it at the correct height throughout the growing season.
To do this, always follow the one-third rule. In simple words, never take more than one third of your grass length in one go. Cutting it down further can scalp the lawn and stress the turf. Instead of focusing on healthy growth, it must use its energy to repair the damage, meaning it takes longer to recover from the mow and its overall resilience drops. This makes it more susceptible to pests, diseases, and of course, weeds.
If this leaves your grass quite long and you would prefer a shorter length, use a 'staircase technique'. This involves lowering the mowing height gradually with each mow, just like walking down a staircase, rather than doing so all at once.
Overseeding
Prioritising overseeding your lawn throughout the season helps to create that thick, dense, healthy turf that crowds out weeds by leaving them no space, sunlight, or nutrients to establish.
To do this, aim to spread around 25 grams per square metre during either spring or autumn. During these times of the year, grass has the highest germination rates as the soil tends to be moist and temperatures are mild. However, you can still overseed your lawn during summer, just make sure to stay on top of watering the seeds and do not let them dry out.
Soil Improvement
Keeping your soil healthy throughout the growing season is extremely important if you want a weed-free lawn, and it is something that has personally made a lot of difference to my garden.
Healthy soil will allow your turf to get the water and nutrients that it needs more easily, since it will not be compacted, while allowing your lawn to develop deeper roots. This will positively impact your lawn's health and allow it to handle tough conditions, such as drought, better, without allowing weeds to take hold in that moment of weakness.
To achieve this, aerate your soil once or twice a year during spring or autumn, to break up any compacted soil, and top-dress it to improve its structure and drainage.