September's when we start getting the "should I wait until spring?" question on site visits. For most jobs, the honest answer is no — autumn is when a garden actually needs attention, and it's also the best window of the year to get hard landscaping booked in. Here's what's worth doing now.
Book hard landscaping before the ground turns against you. Patios, paving, fencing — the ground has had all summer to dry out and firm up, which makes it easier to work with than either a waterlogged November or a frozen January. Mortar and jointing compounds need a few degrees above freezing to cure properly, so once the first proper frosts hit, most hard landscaping work pauses until spring anyway. Everyone else is also thinking "I'll sort it in spring" right now, which is exactly why diaries fill up fastest in March. Book in autumn and you're finished before that queue even forms.
Stay on top of leaves, don't wait for one big clear-up. Wet leaves left sitting smother lawns and turn stone patios slick — algae takes hold fast in damp, shaded leaf litter. A weekly clear, or a blower if there are mature trees overhead, keeps both safe underfoot and stops the lawn coming back patchy and yellow in spring.
Give the lawn its last real push of the year. Aerate anywhere compacted, overseed thin or bald patches while the soil's still warm enough for germination, and raise the mower blade for the final cuts. Grass scalped too short heading into autumn recovers slower and gives moss an easy opening over winter.
Check drainage before the weather actually turns. Clear gutters, downpipes and any patio or driveway drains now. A blocked drain in a dry September is a five-minute job; the same blockage in November after a week of rain is a flooded patio and a much bigger problem.
Jet wash and reseal natural stone. Sandstone and porcelain both handle a British winter fine on their own — but algae and moss get a serious head start on stone that's already dirty when the wet months set in. A wash and reseal now is the difference between a patio that stays safe underfoot and one that's a slip risk by December.
None of this needs a lost weekend — most of it's a morning's work. The one item on this list with an actual deadline is the hard landscaping: book it now and it's done and settled before the ground gets too wet or cold to work with.