September marks the first month of autumn, and your garden will start to go through a number of changes as the weather gets cooler and damper. This means that there’ll be plenty of things to add to your gardening checklist.

Early autumn is a great time to prepare your garden for the winter, plan for next year, and tidy up after the summer. With that said, here are 13 jobs to do in your garden this September.

1. Collect seeds

As we head into autumn, continue harvesting ripe seeds from any summer flowering plants that you want to grow again next year. Only harvest the seeds from flower heads when they are hard and brown. Then store them in brown paper bags labelled with the name of the plant, the harvest date, and any other important information, so that they’re ready to sow next spring. You should also make sure that seeds are completely dry before you store them away – if needed, place them on a sheet of newspaper and let them dry out for a few days first.

Once you have your little brown packages, place them in an airtight container to make sure they stay dry until they’re ready to be sown. If stored correctly, most seeds will be viable for about three years after their harvest date.

To find out more about how to collect and store seeds, check out this handy guide from the Royal Horticultural Society (RHS). The video below will also show you step-by-step how to collect seeds from your garden.

2. Divide herbaceous perennials

Herbaceous perennials are those which have non-woody stems and reach their full height and flowering potential within one year. They then die back over the winter and reappear in spring.

As the weather gets cooler, dividing your herbaceous perennials will help them to reboot and re-energise, so that they return with even more vigour next spring. Some people also divide their herbaceous perennials in order to grow more of their favourite plants.

Plants like to be divided in different ways at different times of the year, so it’s important to check whether September is a good time to divide yours. Salvias, Helenium, Helianthus, and Japanese anemones are examples of perennials that divide well in September.

For more tips on how and when to divide herbaceous perennials, take a look at this guide from the RHS. Alternatively, have a watch of the Waitrose video below which will guide you through the process.

3. Harvest vegetables and plant autumn/winter ones

There’s an abundance of vegetables that will be ready to harvest this September, including peppers, sweetcorn, and courgettes. This guide from the National Trust has some helpful information about what vegetables to harvest in September – plus some recipes that you could use them in.

Just because summer’s over and it’s time to harvest some of your existing veg, that doesn’t mean you can’t continue growing your own fresh supply of the good stuff throughout the winter months. There are plenty of hardy vegetables that you can plant now and enjoy during the colder weather, and most can be sown or planted directly outside.

Onions, garlic, and radishes are often popular choices. To find out what other vegetables you can start growing during the autumn season, take a look at this article from the A.Vogel website. You can also buy seasonal boxes containing a range of different seeds on Seed Pantry’s website. If you select their Grow Club Discovery Box, you can choose six different seed types from their autumnal collection.

4. Plant evergreen trees and shrubs

Evergreen trees and shrubs are much more likely to establish themselves and survive during autumnal weather when the soil is warm and moist. So if you’ve been thinking about planting any, then this is the month to do it with confidence.

For the best results when planting evergreen trees and shrubs, you can prepare the soil by adding some nutrient-rich compost to it. You can also protect young trees and shrubs from gusty winds by attaching them to a stake or a cane. The video below will show you how to plant and stake a tree.

If you’d like some inspiration to help you decide which trees to plant this month, then consider olive trees, fig trees or Japanese Quince.

5. Dig up any remaining potatoes before they get eaten by slugs

During autumn, when soil tends to be warm and moist, slugs become far more active – which could put your potatoes at risk. Potatoes make a tasty feast for slugs and they’ll be the obvious culprits for holey potatoes.

To keep your potatoes safe, make sure you lift them from the soil as soon as possible – main crop potatoes are usually ready around mid-September. Leaving them in soil longer than they need can be a recipe for disaster. To find out how and when to dig up your potatoes, check out this helpful guide from Gardening Know How.

Potatoes grown outdoors in autumn will also be more susceptible to blight – a disease caused by fungi. Potatoes suffering from blight might survive if the blight is caught early enough. For more information on blight and how to treat and prevent it, have a read of this article from GardenFocused.

Top tip: Some types of potatoes are more susceptible to slug damage than others. If your soil seems to be popular with slugs, then it’s best to avoid ‘Maris Piper’, ‘Marfona’, or ‘Estima’ varieties. Instead, opt for ‘Romano’, ‘Lady Rosetta’, or ‘Pentland Dell’, which are less susceptible to slug damage.

You could also try growing ‘Wilia’, ‘Heather’, or ‘Kestrel’, which mature early and can be lifted during August, before the soil starts to become damp and humid. During a very wet summer, these will need to be lifted as soon as you notice any signs of trouble.

6. Plant spring-flowering bulbs and seeds

If you want to guarantee that you’ll have flowering plants in your garden next spring, then you’ll need to sow your seeds and plant your bulbs this autumn so they can start putting down roots. Make sure you choose bulbs that are firm, plump, and free from mould.

Planting bulbs and seeds now will save you spending money on plants during spring and can result in healthier plants, as they will already have had plenty of time to get settled when the time comes from them to flower. Plus, it can be incredibly rewarding to know that you are growing everything in your beautiful garden yourself.

If you don’t currently have any seeds, then Seed Pantry has a great selection of seeds and bulbs that you can plant in September, as well as seed kits that include seeds, growing essentials (including labels, compost, and pots), and instructions on how to sow and care for them.

English Marigolds, poppies, and cornflowers are examples of flower seeds that can be sown now, while daffodils, crocus, and hyacinths are examples of bulbs that should ideally be planted by the end of September.

7. Harvest apples

September marks the beginning of apple-picking season, so get ready to make some room in your fruit bowl. You’ll know whether the apples are ready or not because they’ll come away easily if you give them a gentle twist.

Try to harvest apples before they fall to the ground and start rotting or become a tasty treat for your garden’s wildlife. If any apples do fall, but only have minimal damage, then consider cutting off the bad bits and using them in a recipe – perhaps a crumble or strudel. For inspiration, it’s worth browsing Delicious magazine’s huge selection of apple recipes.

To find out what other fruit is ready to harvest around September time, have a read of this article from Brambley & Teal.

8. Give your lawn some TLC

September is often the ideal month to renovate your lawn because the weather is usually still mild and there’s an increase in rainfall – which can help your grass to reach its full potential.

Towards the end of summer, it’s not uncommon for lawns to have an abundance of moss or weeds because they’re lacking in nutrients. But there are a few things you can do to help:

  • Use a rake to remove any moss or thatch (old grass clippings) that have built up on your lawn and pull out any large weeds by hand.

  • Continue to mow your grass regularly while it’s still growing (as long as it’s not too muddy). September can be a dewy month, so it’s best to cut your grass during the day to get a straight cut and to avoid your lawnmower becoming clogged with wet grass clippings.

  • Aerate your lawn to improve drainage. You can do this by making some evenly spaced out holes with a garden fork.

  • Add fertiliser to your lawn. Feeding your lawn during the autumn will encourage strong root growth, help it stay green and healthy, and protect it from frost and diseases during the winter months. You can buy lawn fertiliser on Amazon and all you need to do is mix the recommended amount of feed with some water in a watering can, and apply it evenly over your grass.

9. Keep an eye on your bird feeder

With the changing seasons, comes a change in wildlife, and August can be a busy month – so there’s plenty of reason to keep an eye on your bird feeder. Different bird species will have a range of different autumn activities planned that your bird feeder can help with. Some will be eating as much as they can to prepare for a long winter of hibernation, some will be fuelling up for a long flight, and others will just be stocking up for a cold and unpredictable winter.

Once you’ve established a feeding routine with birds, try to stick to it, as they’ll become used to it and will visit your garden regularly looking for their next meal. The RSPB have produced some useful tips on what to feed birds and how you can keep your feeding station hygienic and pest free, which you can read here. You can also pick large bags of bird feed up for a few pounds in Wilko.

Fun bird-watching facts:

During the autumn, we say goodbye to birds that have been visiting during the summer – including the Willow Warbler which flies all the way from the UK back to Africa! These tiny birds mostly eat fruit and insects during summer, so don’t visit feeders often, but you might see an appearance during the autumn when they start stocking up on nuts and berries to prepare for their 5000-mile journey back to sub-Saharan Africa.

Once Willow Warblers and other summer visitors have left for the winter, we receive a whole new flurry of bird species who come from much colder regions including Scandinavia and Russia and stay with us over winter. These birds include the Redwing, Waxwing, and Fieldfare, so have a look out for them over the coming months.

If you’re interested in birds and would like to know more about how to spot them, then you might be interested in our article A beginner’s guide to birdwatching. This handy guide covers everything from the birds you’re likely to see to how to make your garden more bird-friendly.

10. Make your own compost

It takes about six months to make your own compost, which makes autumn a great time to get started because it should then be ready for spring planting. Making your own compost allows you to be in control of what’s in it and avoid any nasty chemicals – plus, you’ll save money and get to recycle garden and kitchen waste.

To get started, you’ll need a large compost bin. It’s possible to make compost without a bin, on bare earth, but this can take much longer. Bins are helpful because they retain warmth and moisture, speeding the composting process up. You can make one yourself if you’re feeling adventurous or pick one up from your local garden centre, Homebase, or B&Q.

The next step is to fill your compost bin with as much organic waste as possible – the more varied the ingredients, the richer your compost will be – and leave it to rot down. You can add things to your bin like teabags, egg shells, leaves, and grass clippings. There are also things that you shouldn’t add to your compost pile, like meat fat, dairy, and bones. If you want to find out more about what to put in your compost bin and what not to, check out this article from Gardening Know How. The video below will also offer you some helpful tips on making your own compost.

11. Clean up

Having a tidy, well-tended garden during the cooler months can help to lift spirits during the cooler, gloomier months and help to welcome spring when it finally comes. After a long, hot summer, there’s usually plenty that you can do to clean up. This includes:

  • Washing down your BBQ and garden furniture with some soapy water and either putting them away or covering them with some tarpaulin to keep rust and moss at bay.

  • Cleaning out empty pots and hanging baskets that contain plants that are past their best and preparing them for your spring or autumn/winter flowering bulbs.

  • Cleaning out birdbaths and keeping them topped up.

  • Cleaning out greenhouses and water butts so that they are ready to be used this autumn. The RHS has a helpful guide on when and how best to do this.

12. Turn over your soil

Soil usually works hard during the summer months, and goes through many cycles of being watered and then drying out – which often causes it to become compacted. This reduction of pore space means that soil will not be able to absorb water fully, and plant roots will not be able to get sufficient oxygen. It also means that the soil will have less microbiological activity, which helps to feed plants and protect them from disease.

Turning over your soil and mixing some compost into it will aerate it, mix up the nutrients, and improve the growing conditions of your soil. The video below will show you how to prepare and improve your soil.

13. Water houseplants less frequently

Many houseplants need time to dry out in between watering so that air can get into the soil and roots can breathe properly. Soil that is constantly damp will also be prone to root rot and an overwatered plant can change colour and start to wilt.

In September, as the temperature starts to drop, it’s important to consider that your plants will be receiving less sunlight and will be absorbing water at a slower rate, so you’ll probably need to water them much less frequently to accommodate this change.

For tips on buying plants that are easy to care for, check out our article 10 low-maintenance indoor plants that can add life to your home.

Final thoughts...

While many see the end of summer as the end of the gardening season, you don’t have to pack up your trough and head inside just yet. From planting evergreen trees and shrubs to making your own compost, there’s plenty still left to do in September for those of you with a green finger.

And for more gardening content, why not visit the gardening section of our site here?

Do you have any additional tips that you’d like to share? Or perhaps you’d like to share a photo of your own green space? Why not share with others on the community forum or leave a comment below.

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