September marks an important seasonal shift in the garden. The days grow shorter and the soil cools, transforming a once-vibrant summer lawn into a patchy, dry, or compacted one from heavy use.
Though autumn doesn’t bring the obvious growing energy of spring, it’s one of the key periods to start preparing your lawn for wintry conditions and the subsequent spring regrowth. Left unattended, compacted soil and worn grass can give way to moss, thatch build-up, and poor drainage. All these conditions can compromise the strength and appearance of your lawn over time.
According to composite decking brand TrexPro, who collaborated with outdoor living expert Simon Parry of Simon Parry Landscaping & Gardening, there’s one job to prioritise before the frost sets in. Aeration may not be glamorous, but it can dramatically boost air circulation, water absorption, and root strength.
Horticulturalist and BBC Gardeners’ World star Monty Don has long championed this overlooked job, insisting that it is “always” important to do it at this time of year.
“You can use a fork by working the tines into the ground at 12-inch intervals or, for a larger lawn, hire a rolling hollow tine or slitter,” Monty advised.
“Ideally, this is followed by working sand into the holes they create with a stiff brush.”
Simon’s advice concurs, with the expert noting that the process is essential after a season of garden traffic and summer sun.
“Aerating can help by improving air and water flow to the roots,” he explained, recommending that gardeners push in and wiggle the fork, spacing holes 15cm apart.
When done properly, aeration “lets stale carbon dioxide out, in turn, making room for fresh new oxygen to go in.” It also breaks up compacted earth and penetrates any thatch that may be smothering the grass.
To complete your September lawn care, follow aeration with a high-potassium, high-phosphorus, low-nitrogen autumn feed to build robust root systems.
Keep mowing on dry days, aiming for a grass height of around 4–5cm.
And if there are bare patches, now is the time to address them, with Monty advising: “The seed should germinate and grow in days. Do not mow it for at least a month and if it looks unsightly going into winter clip the new growth with shears.”