Summer officially gives way to autumn on the 22nd of September, which is known as the autumnal equinox, but for the lawn owner autumn begins much earlier. This is because the green keeping tasks for autumn begin from the 1st day of September.
Your first task is to make changes to your mowing method, I would suggest raising the height of cut by 1cm above your summer mowing height which will give you an ultimate mowing height of 3cm (1 ¼ inches). The reason why you raise the cut to this height in autumn is to allow for the slowing of grass growth, on top of this I would usually mow just once a week once this growth begins to slow.
Should your lawns suffer from slow growth in the spring or during dry spells in the summer you may consider applying an autumn lawn feed to develop strong roots and hardiness. If you feel your lawn is not all it should be and would benefit from this autumn pampering then by all means apply the fertiliser but ensure it is specially formulated for autumn application, an autumn lawn feed such as this contains phosphates and potash whilst omitting nitrogen which would cause unwanted growth.
Many gardens may have goalmouths and beaten paths to washing lines that are tread-bare, sparsely populated by grass or compacted. Address these now to have them ship-shape for next season, start by driving the prongs of a garden fork approx 15cm (6 inches) into the compacted turf at various points throughout the affected area. This is a form of aeration, which allows more air to reach the grass plants roots on compacted soils.
To thicken up your grass sward in these high traffic areas we must introduce fresh seed, so firstly we must create a seedbed. Add a light layer of clean loamy topsoil (This is available bagged in most garden centres), rake this with a flat garden rake to the consistency of large cake crumbs and follow this by shaking on some lawn seed at a rate of 40 to 50g per square metre. Tamp down lightly with the flat of the rake to ensure firm seed-soil contact, alternatively on large areas use a light garden roller. Try to avoid mowing the reseeded area until next season, as most lawnmowers tend to unsettle the new seed due to their vacuum action.
As well as being a good month for reseeding bare areas, September is also a good time to sow new lawn from seed, with many being sown over the early autumn weeks.