Looking for September garden jobs to add to your to-do list? The good news is that late summer is a great time to be outdoors, especially if there's still plenty of warm sun to enjoy while you're getting on with those crucial garden tasks. As things slowly shift into autumn mode there's lots to do ahead of the arrival of cooler weather.
Key September gardening jobs include picking late summer flowers for the house and harvesting the last crops from the veg patch.
This month is also about looking ahead and preparing for the growing season to come, tidying the garden, completing autumn lawn care jobs and sharpening secateurs ahead of tackling seasonal pruning.
1. Tend to flower beds and the veg patch
One of the most important garden jobs for September is to keep deadheading flowering plants to extend bloom time and keep flowerbeds looking good. This also prevents plants from fading fast as it stops them putting all their energy into making seeds.
Clear spent annuals from flower borders and raised beds, and add them to the compost heap, which can be used to enrich the soil for the next season.
“While we’re past the peak of the growing season, September still offers plenty of meaningful jobs for the productive garden,” says Penny Hemming, head gardener at the Riverford Field Kitchen in Devon. “In ornamental beds, leave stems and seed heads standing through winter. They might look a bit scruffy, but they’re a haven for insects. Frost sits beautifully on seed heads, and their hollow stems offer vital shelter to insects. So only cut back where needed.”
if you want to keep the veg patch going Penny says you're good until the end of September for a final sowing of winter radish, plus it's a great time to sow hardy green leaves like pak choi, mustards, mizuna, and tatsoi. They thrive in cooler weather and can be harvested through winter.
“This is the ideal time to tidy up summer flowers. If your roses have finished flowering, now is the perfect time to prune them," says gardening expert Chris Bonnett. "Clear away the remnants of any summer fruits. Remove the straw from your strawberry plants and neaten up any untidy raspberry canes as well."
Penny Hemming is head gardener at the Riverford Field Kitchen in Devon. She can usually be found in 'Penny's Polytunnel', an Aladdin's Cave of unusual veg and herbs, used to supply the Field Kitchen restaurant. She also runs guided tours and farm walks, as well as hosting workshops.
Chris Bonnett, founder of the online garden centre GardeningExpress.co.uk, has over 20 years’ experience in horticulture. His journey in the industry began as a teenager, when he merged his love of the outdoors with the internet to make quality plants accessible across the UK and Europe.
2. Enrich the soil in September and benefit next year
If you don’t already compost now is the best time of year to start, especially if you're looking for ways to make your garden more eco-friendly. "September’s cutbacks make great compost material," says Penny Hemming. "Establish a compost bin and add prunings, leaves and grass clippings. Cover to keep the rain out and the compost warm. Come spring, you’ll be able to spread three inches of homemade compost over your beds to get them off to a flying start."
If you already compost, start to spread a generous top dressing of rich compost over the next couple of months to provide good ground protection over winter and enrich the soil longer term. This will give all your growing endeavours a boost next spring and summer.
Towards the end of September mulching any bare soil with compost will help prevent erosion, suppress and kill weeds, retain moisture and feed the soil through winter.
Another important September garden job is to rake fallen leaves and store in bags to create nutrient-rich leaf mould that can also be used as mulch once it has rotted down.
3. Clean ponds and water features
Late summer is a good time to freshen up your garden pond ideas and water features. Check for any build-up of plant debris as this can lead to problems with algae and blanket weed if ignored, as well as cause the water to become cloudy.
Scoop out any floating leaves and cover your pond with netting to keep autumn foliage from trees and shrubs at bay. Ensure nets are secure, so they're not a hazard to birds and other wildlife.
Top up water levels in fish ponds as these can drop a little at this time of year, particularly if there is a run of warm September weather. Wildlife ponds will be fine until it rains.
4. Propagate perennial plants and take cuttings
One of the main garden jobs for September is to plan ahead. Have you got gaps in the garden where this year's hot weather took its toll? If so, lift and divide perennials that have outgrown their space. This will both refresh the plant and create new clumps to fill gaps. Planting in autumn also lets plants put down roots and get established before winter.
September is also the perfect month to take semi-ripe cuttings of lavender, hydrangeas, and herbs such as rosemary. “Cut just beneath a leaf node, strip off excess foliage, and place cuttings around the edge of a pot filled with peat-free compost,” advises flower expert Julie Woodford of Madge & Ivy Flowers. “Water well, keep out of direct sun, and in two to three months roots should appear, ready for potting on.”
September is also a great time to curl up with a seed catalogue and dream of next year’s planting, says Julie. "It’s also the time to order bare-root roses, ready for autumn planting. These timeless English garden favourites will settle in over winter and flourish in the seasons to come."
Julie Woodford is a seasonal florist and flower grower based in Berkhamsted, and owner of Madge & Ivy Flowers, growing and sharing beautiful, seasonal flowers in Hertfordshire. Julie's approach is based on a deep respect for the land, using sustainable practices, nurturing biodiversity, enriching the soil, and doing her bit to enhance the overall well-being of the local environment.
5. Choose and plant spring bulbs
September is also the time to buy and plant spring bulbs, so you'll be rewarded with flowers just as the garden reawakens. September is ideal for planting narcissi, alliums and muscari, while tulips prefer to be planted in colder ground later on in the year, and can go in as late as November as long as the ground isn't frozen.
"The soil in September retains some warmth from the peak summer months, so it’s the perfect time to plant spring-flowering bulbs," says gardening expert James Ewens from Green Feathers. "This lets the roots establish before the winter bite kicks in. By staggering different varieties, you can expect months of colour, from crocuses showing their faces in early February to late tulips in May."
Pollinators need all the support they can get, and they’ll thank you for your efforts, says James. "Early spring blooms provide some of the first vital nectar sources for bees emerging from winter hibernation."
James Ewens is a gardening expert at Green Feathers, the UK’s leading supplier of bird box and wildlife cameras, and passionate about all-things-sustainability and the environment.
Shop spring bulbs to plant in September
Plant anytime from August to November, pointy end up, 10-15cm deep with 8-10cm between each bulb in borders (less in containers). Flowers in April.
Plant in September or October, in holes about three times deeper than the bulb's diameter, pointy side up. Gently fill the holes with soil and water. Flowers in July to August.
Plant muscari bulbs from September to December in large groups, at a depth of 10cm and a distance of 5cm apart. Flowers in April to May.
6. Get trees and shrubs in shape
One of the key garden jobs for September is to neaten up trees, hedges and shrubs. It's especially important to give evergreen varieties like laurel, bay and privet a light trim to get their structure shaped up, as these are often the main interest during the winter months when everything else dies back, so need to look their best. It's also a good time to cut back climbing plants like ivy and Virginia creeper.
Often all that's needed is a light trim as plant growth slows anyway at this time of year. Removing any dry, dead or diseased stems and foliage is important, as well as thinning out crossing branches to ease congestion and improve air circulation in the heart of the plant.
7. Use September to get your lawn winter ready
Carry out essential lawn care and maintenance to prepare for winter. "Start by aerating the lawn with a garden fork, then remove any thatch with a rake," says Richard Barker. "Any dead or bare patches revealed after raking may need to be reseeded. It's best to sow new grass seed as soon as possible, as in September the soil is still warm and the increased levels of moisture create the ideal conditions for grass growth."
If your lawn tends to get waterlogged in winter or the soil feels compacted, aeration (relieving compaction) is especially important. Learning how to scarify your lawn (removing thatch and moss) will also help airflow and nutrient absorption.
"Looking after your lawn in September and throughout autumn is essential for healthy grass in the colder months," says gardening expert Helena Jones from Hedges Direct. "Continue mowing, but raise your blade height slightly to keep the lawn dense and resilient. September is a great time to apply an autumn fertiliser while growth is still active." Choose a fertiliser that is rich in potassium to strengthen grass roots before winter.
Helena Jones is currently head of commercial at Hedges Direct Limited, having been in the business since 2022. Her expert knowledge of the product range, and horticulture in general, helps Hedges Direct continue to be an online market leader.
8. Clean patios and decking
After a summer of entertaining, two of the must-do September garden jobs are to clean decking and also clean patio slabs to remove any dirt, algae, moss and grime that has built up in the warmer months. Cleaning them now also helps to prevent slippery surfaces in winter.
"For wooden decks, remove furniture and planters before sweeping away leaves and loose debris," advises outdoor living expert Simon Parry. "Use a stiff broom and a decking cleaner with a bucket of warm water. Once washed, rinse thoroughly and apply oil and/or sealant."
For composite decks, Simon advises removing furniture and planters and again sweeping away leaves and loose debris. Then simply clean the deck using a bucket of warm, soapy water and a sponge. No sealant or oiling necessary.
To clean your patio, scrub with a stiff brush to remove any grime and dirt, or use a pressure washer. "Start by sweeping the area to remove loose debris, dirt, and leaves," advises home improvement expert Nick Ee from Black+Decker. "Attach the pressure washer to a water source and select an appropriate nozzle."
Nick suggests beginning at one end of the patio, holding the nozzle about 12 inches from the surface, and spraying in even, overlapping strokes to avoid streaks. "For tougher stains or moss, use a detergent specifically designed for pressure washing and let it sit for 5-10 minutes before rinsing with the pressure washer. Then, rinse the area thoroughly with clean water and allow it to dry completely.”
Simon Parry is a TrexPro installer for Trex UK, and director of Simon Parry Landscaping & Gardening. Established in 2011, the specialist gardening company is based in south Birmingham and offers a range of services from basic mowing and maintenance, to full garden transformations.
Nick Ee is gardening product and training manager at Black+Decker. He has over 10 years’ experience working in the home improvement industry. Prior to Black+Decker, Nick was self-employed running his own van of tools and through that has gained a wealth of real-world experience in the residential construction and gardening industry.
9. Tackle weeds
Throughout September, make sure you remove any remaining weeds from your garden. It's important to do this now as the weeds will soon go to seed and spread around, which means more rapid growth next year.
"Most weeds can be easily pulled out by hand, but for weeds with shallow roots you can also use a hoe," says Simon Parry. "For deeper rooted weeds more force may be needed, along with a weeding knife."
Don't just stop at your flowerbeds either, get to work removing weeds from gravel as well as removing weeds from your patio.
Shop weed removal tools
This hand weed remover tool has a sawtooth, so loosens the soil and weeds more easily. Perfect for removing dandelions, horse grass, duckweed and other common garden weeds.
Strong, lightweight and durable tool with rust-resistant, stainless-steel claws for effective weed removal. Handle features a sliding mechanism that allows for easy ejection of pulled weeds.
Incredibly sharp and useful for keeping weeds at bay in your borders or raised beds, this weeding hoe is a must-have maintenance tool. Available in both left and right handed designs.
10. Collect seeds in September and dry them for sowing next year
Another one of the important garden jobs for September is gathering seeds from the garden to dry and store for planting next year. It's a great opportunity to increase the number of plants in your garden for free.
"Collect seeds from hardy annuals and perennials before they are able to self seed," says Richard Barker, commercial director of LBS Horticulture. "Usually, plants will set seed around two months after they have flowered, but only collect seeds from plants that are healthy as they are more likely to be viable."
Start collecting seeds by cutting open dried flower heads with a sharp pair of scissors. Once harvested, leave the seeds to dry thoroughly for a week or so before storing away safely until outside conditions are appropriate for sowing.
Richard Barker is an expert in horticulture and the commercial director at LBS Horticulture. He is keen to share his knowledge with both experienced and beginner gardeners, and prides himself in keeping up to date with the latest horticultural trends.
Keeping on top of these simple gardening jobs in September will ensure you're in the best place for the months ahead. Little and often is typically the best way to keep on top of garden maintenance.
September is also a great time to give your garden tools some TLC, so get up to speed with how to sharpen secateurs in preparation for those autumn pruning jobs that lie ahead.
