Get the right jobs done this month and your garden heads into winter in good shape, ready to come back stronger next spring.
Miss them, and you’re catching up in November instead, with less daylight and harder ground to work with.
We look after gardens and grounds across Glasgow and Lanarkshire all year round.
This month that means feeding lawns, cutting back borders, and clearing greenhouses before the cold sets in.
Here’s what’s on the list for your garden this month.
Get your lawn ready for winter – By Scotland’s garden design experts
The soil’s still warm enough for roots to grow in September, and the heavy summer footfall has eased off. Both make this the best window to prepare your lawn for winter.
Scarify, aerate and feed
Start with one last cut, raising the mower blades slightly so you’re not scalping the grass back to ground level heading into shorter days.
Scarifying comes next.
It means raking out the thatch, the dead, matted layer of old grass and moss sitting under the surface.
Clear it and water and nutrients can finally reach the roots.
Aerating your lawn does a similar job for compacted soil.
Spike it with a garden fork, or go over it with a hollow-tine aerator if the ground’s really packed down.
Follow both jobs with an autumn feed, a fertiliser formulated for root growth rather than the leafy green flush a spring feed pushes.
Patch up bare areas
Bare patches are easiest to fix now, while the soil’s still workable.
Rake out any dead grass, work in some fresh topsoil, and oversow with a hardy seed mix suited to the spot.
Most patches knit back together within a few weeks if you get them done in September rather than waiting for spring.
If large parts of the lawn are past saving, it’s often quicker to lift and relay with fresh turf than to keep patching it.
Get spring bulbs in the ground
September is when spring bulbs go in the ground, and daffodil, crocus and hyacinth are all worth planting before the soil turns cold.
New plants like these settle in far better over a cool autumn than a rushed spring planting.
Plant spring-flowering bulbs into borders and pots now for a solid stretch of spring colour that needs barely any more effort until next spring.
We’ve covered exactly what to plant, and when, in more detail in our guide to what to plant in September.
Read that first if you’re planning new borders rather than just topping up what’s already there.
Cut back and tidy your borders
Deadhead and cut back perennials
Herbaceous perennials that have finished flowering benefit from a proper cut back now, rather than being left to collapse into a soggy mess over winter.
Cut spent stems down close to the base once the foliage has died back.
Leave a few seed heads standing too, echinacea and sedum especially, for birds and for some winter structure in the border.
Deadheading anything still flowering keeps the display going a little longer and stops the plant wasting energy on seed instead of next year’s roots.
Once flowering has finished for good, tidy the foliage away and add it to the compost heap.
Overcrowded perennial clumps are worth dividing now too.
Lift and split them with a fork, and you get free new plants while the originals flower better next year.
Roses and summer bedding
Roses are still worth deadheading through September, though hold off on any hard pruning until late winter.
Remove faded blooms just above a healthy leaf joint and the plant will often push out one more flush before the cold sets in.
Summer bedding plants that have gone leggy can come out now, clearing the ground for spring bulbs or a fresh planting scheme.
If you’re rethinking a whole flower garden rather than just tidying what’s there, our garden design team can help plan it.
Bring in the last of the harvest
You can still sow in September for one last crop, even while most of the summer harvest is coming in.
Potatoes, apples and pears
Lift maincrop potatoes once the foliage has died back, typically some point in September.
Choose a dry day, and ease them out with a fork rather than a spade, so you’re not spearing a few by accident.
Let them dry on the surface for an hour before storing them somewhere dark and frost-free.
Apples and pears are ripening fast this month too. Cup the fruit and twist gently.
If it’s ready, the fruit comes away easily, stalk and all. If you have to tug hard, give it another week.
Berries, beans and onions
Raspberry canes, the autumn-fruiting varieties, and any late blackberry brambles are worth checking every few days.
A warm spell can ripen several days’ worth of fruit within a day or two.
French and runner beans are winding down but usually still cropping, so keep picking to squeeze a few more weeks out of the plants.
Onion sets from earlier in the year should be lifted and dried in the sun for a few days. Then store them somewhere cool and airy once the tops have fully withered.
Protect the greenhouse and tender plants
Bring tender plants in before the first frost
Greenhouse crops like tomatoes, chillies and cucumbers are still ripening, but temperatures start to drop fast once September gets going.
In a Scottish garden, the first frost often arrives earlier than the calendar suggests, and it damages anything tender left outside overnight.
Bring anything tender indoors before that first cold snap: pots on the patio, fuchsias, pelargoniums, and any tropical-looking specimens that won’t survive a frost outdoors.
A bright windowsill or an unheated porch works for smaller plants if you don’t have space under glass.
Keep sowing while the soil’s warm
The soil is still warm enough this month to sow hardy varieties direct in the greenhouse border or in trays.
It’s worth sowing winter salad leaves now too, while there’s still some warmth left in the ground.
Ventilate on mild days and ease off on damping down, since a greenhouse holds too much moisture once the weather turns cooler and wetter.
General maintenance and wildlife jobs
Fallen leaves and soil health
Fallen leaves build up fast from mid-September, and left alone they smother the lawn and borders underneath.
Rake or blow them off grass and paths regularly rather than leaving a good autumn’s worth to build up in one go.
Autumn leaves make free, effective organic matter for the garden.
Bag them up (damp leaves in a punctured bin liner work fine), and leave for a year or two to make leaf mould.
That gives you a crumbly, soil-improving mulch that’s perfect for borders.
Watch for mould developing on leaves left in a wet pile without airflow, and turn the bag occasionally if that happens.
Ponds and garden birds
Net ponds before the leaves really start falling, since decomposing leaves foul the water and use up oxygen that fish and wildlife need over winter.
A stretched net also keeps cats away from anything still active in cooler water.
Garden birds appreciate the help too.
Clean out nest boxes now that the breeding season’s over, and top up feeders as natural food sources dwindle.
Leave a shallow dish of water out too, once the weather turns wet or icy.
Weeds and pest checks
Weeds are still growing while the soil’s warm, so keep on top of them now rather than letting them set seed through your borders.
Check new and existing plants for pests and diseases while you’re out there too.
Catch a few aphids or a patch of mildew now and it’s a five-minute job. Left until spring, the same problem can mean cutting whole stems back hard.
Clean and sharpen your tools too before they go into winter storage, ready for spring.
Hedges and trees
Hedges and trees benefit from a tidy-up too.
Most formal hedges can take one last prune in September. Deciduous trees and shrubs are still easy to assess before their leaves drop and hide any deadwood or storm damage.
Our tree surgeons carry out exactly this kind of health check, if you’d rather have a certified arborist look over anything overhanging a building.
Frequently asked questions about garden jobs in September
What plants need cutting back in September?
Herbaceous perennials that have finished flowering are the main candidates, along with faded summer bedding and any spent annual displays. Leave a few seed heads standing for birds and winter structure rather than cutting everything back to bare soil.
Is it too late to sow or repair a lawn in September?
No, it’s close to ideal. The soil’s still warm enough for grass seed to germinate and root before winter. New turf or overseeded patches get a head start most spring sowings can’t match. Leave it much later and germination slows right down as the ground cools.
When should I plant spring bulbs?
Daffodils go in from mid-September, ahead of tulips, which prefer the colder soil of November. Crocus and hyacinth follow the same early rule. The sooner they’re in the ground, the more time their roots have to establish before the first proper frost.
What should I plant outside in September?
Spring bulbs, hardy perennials, trees and shrubs all do well from a September planting. Our full guide to what to plant in September covers flowers, vegetables, trees and shrubs in more detail.
Get help with the jobs you don’t have time for with GGM Landscaping
The amount of light reaching your garden drops fast from here. Jobs done now count for more than the same jobs squeezed into a grey October weekend.
Not every job needs doing in one weekend, and late summer into late September is a reasonable window for most of it.
If your garden’s list keeps growing faster than your free time, our team can take it on.
We handle one-off garden maintenance and lawn care, and full grounds and estate maintenance contracts that keep your garden looking its best.
Monthly gardening never falls to the bottom of your list!
Get in touch for a free garden consultation and we’ll help your garden establish before winter. You’ll see the difference in thicker grass and better flowering come spring. Call us on 07946 322717 or drop us a message to get started.