September is one of the most important months in the gardening calendar, both for preparing the garden for autumn and for setting it up for the following spring. Gardening expert Monty Don has highlighted a long list of tasks to tackle, from pruning roses to trimming hedges, but the lawn demands particular attention with three essential jobs.
Why September is the right time
Monty suggests September is the perfect time for these tasks because temperatures have eased off and lawns should have recovered from the summer heatwave. In a 2024 blog post, he recommended sowing grass seed, repairing lawns, and aerating them.
Sowing grass seed and repairing lawns
Monty wrote: "This is an ideal time of year to either sow or turf new grass or to repair patches and worn areas on your lawn."
He advised that for a worn area of thin grass, gardeners should rake away all thatch and moss, remove all weeds, and thinly scatter grass seed, watering well and keeping it damp. The seed should germinate and grow in days.
Monty recommended holding off mowing the lawn for at least a month. If it appears "unsightly" heading into winter, he suggested trimming the new growth back with shears.
For a larger area, he advised neatening the edges with a sharp spade, forking over to break up compaction, and either scattering seed or laying turf to fit, ensuring the edges are butted tightly against the existing grass.
Monty added: "Like grass seed, it is important that turf should not be walked on or mown until growing vigorously, which will indicate that the roots have become established and are growing strongly." Depending on the weather, this may mean leaving it uncut until next spring.
Aerating the lawn
Aeration is another widely recommended lawn task for September. It enhances airflow, improves water absorption, and allows nutrients to reach grass roots more effectively.
Monty said: "Even if your lawn has come through the summer unscathed, it is always a good idea to aerate it at this time of year." He suggested using a fork by working the tines into the ground at 12-inch intervals or, for a larger lawn, hiring a rolling hollow-tine or slitter. This should ideally be followed by working sand into the holes with a stiff brush.
Finally, Monty recommended giving the lawn a thorough scratch with a wire rake to clear away all thatch and moss. Although it may look sparse afterwards, the lawn will be fully "rejuvenated" come next spring.
