By Ruth Hayes published
Our September gardening jobs are just what you need if you want to ensure your garden looks as good as possible as we head into fall.
Many people make the mistake of thinking that fall and winter are ‘quiet times’ for gardeners, a notion that makes most gardeners fall about laughing! Because we all know that wherever the season, there are jobs to do out there and September, which is widely regarded as the gateway to autumn, is no exception.
Whether it's thinking about what to plant in September, or considering what weeding and watering needs to be done, there are plenty of important tasks you could be getting on with this month.
September gardening jobs: 16 key garden tasks
It's easy to prepare your garden for the cooler weather ahead with our list of essential September gardening jobs. These jobs are quick, easy and great for keeping you out in the fresh air this month.
1. Plant spring bulbs
From now until mid-November the garden centers, shops and online outlets will be selling spring-flowering bulbs.
Planned right, they will perform from early in the year right through to late summer, starting with snowdrops and crocuses before moving on to daffodils, anemones, tulips, crown imperials (Fritillaria imperialis), and the dazzling array of summer alliums.
Bulb plants come in different heights too, from ground-hugging Anemone blanda and little scilla, crocuses and winter aconites to stately camassia and bell-flowered Nectaroscordum siculum, which produce entrancing arrowhead seedpods.
When planting bulbs, remember that most spring bulbs will favor a sunny spot, though a little shade will prolong the brilliance and longevity of the flowers. Some, though, do best with a little shade, especially those that originate from a woodland setting, such as snowdrops and bluebells.
Scilla, muscari and cyclamen will also thrive in a little shade, as long as you incorporate lots of well-rotted compost or manure into the soil at planting, and keep them well watered.
If space is at a premium, bulbs will grow extremely well in pots. Crocus, hyacinths, species tulips, which are smaller, less showy but no less desirable, than larger bedding varieties, Iris reticulata, scillas and narcissi all look stunning in garden planters.
Use peat-free compost with added fertilizer and make sure you raise the pots up on feet so excess water can drain away, helping prevent the bulbs from rotting due to waterlogging.
2. Create a bulb lasagne
Why not learn how to plant a bulb lasagne for one of your September gardening jobs? If you haven't heard of this ingenious method of planting bulbs before, it's basically a means of growing several varieties of bulb in the same container.
They are planted at different levels and each variety is separated by a layer of compost 1-2in (3-6cm) deep. You could start with daffodil bulbs on the bottom then tulips, anemones and finally little Iris reticulata. The result is a mix of plants and a prolonged flowering season.
Once your containers are full of bulbs, move them somewhere sheltered for winter and bring them out to be the centerpiece of your patio gardening ideas when they start to grow in spring.
Top tip: There is no need to worry that the bottom layers of the lasagne will be unable to flower – the shoots are able to bend past the higher bulbs until they reach the light.
3. Rake up fallen leaves
This season is called ‘fall’ for a reason, and that reason is starting to make itself clear all over our gardens and pathways. Fallen leaves need to be raked up and removed from the grass because they block sunlight, causing yellowing patches, and can also harbor pests and diseases.
The timely leaf drop is nature’s way of getting rid of waste, but it also gives us the opportunity to make leaf mould, which is one of the best soil improvers available.
If you want to learn how to make leaf mould, simply rake up and store fallen leaves somewhere – a wooden framework with wire mesh sides is ideal or, if you don’t have space, put them in black binliners with holes pricked in the side and store them somewhere out of the way.
Leaves can take a couple of years to break down but the end result is gorgeous crumbly leaf-mould that your soil will love.
Top tip: Water helps leaves break down faster, so leave leaf mould bins uncovered so rain can get in and if you are storing leaves in sealed bags, open them every now and then and add some water.
4. Pick ripened fruit and vegetables
Make harvesting fruit and veg as it ripens one of your September gardening jobs otherwise it will spoil on the plant, which can cause other goodies on the same branch to deteriorate as well.
Tree fruit such as apples and pears should be stored somewhere cool, dark and well ventilated, ideally with each piece individually wrapped in newspaper or tissue paper to prevent them bruising.
Remove and use as they start to ripen as one ripe fruit will turn the rest.
Other produce can be frozen, dried, jammed, pickled or made into chutneys – delicious, and ideal as Christmas gifts!
Top tip: Don't forget to leave a few fallen apples on the grass to provide vital nectar for late-flying insects before they hibernate for winter.
5. Clear out borders and pots
As fall progresses and the temperature drops, summer bedding will start to wither by the wayside.
Remove it and add it to the compost heap, as long as it isn’t diseased or full of pests, and fork over your soil. Enrich it with well-rotted manure or compost, or dig in some chicken manure pellets.
You can now either let your flowerbeds lie fallow through winter or plant spring bedding and bulbs.
Also start cutting back and deadheading perennials that have passed their best, remembering to leave a few stems standing through winter as they are handy hibernation homes for invertebrates and garden insects.
Top tip: Keep an eye out for robins and other garden birds lurking nearby when you turn over the soil – they are on the lookout for juicy worms and pests to turn into a tasty treat.
6. Plant, move and divide perennials
The soil has been warmed by summer sun and is now dampened by seasonal showers, so between September and November you should take the most of these ideal conditions and prioritise your perennials.
They can be planted, moved and divided now, ideally on a still, overcast day when wind and sun won’t dry out the roots.
When planting and moving, create a hole large enough to take all the roots, but no deeper than the rootball itself.
Add some bone meal to the soil as this will break down over winter and feed the roots when regrowth starts in spring.
Follow these tips for dividing an overgrown perennial:
- Lift it from the soil by digging widely around it and keeping as much soil around the roots as possible.
- Split it into sections using your spade blade or, if the roots are a thick mat, a knife or saw. Find the best garden spade for the job in our handy buying guide.
- You can also place two garden forks back-to-back among the roots and divide the plant by pulling them apart.
- Make sure all the divisions have healthy top growth and roots. It's important to keep watering plants as well as ensuring they are weed-free while they get established.
- Don't be alarmed if your moved or divided perennials droop for a day or so after planting. This is a common occurrence and they will soon revive.
7. Provide plant protection for winter
It is still relatively warm outside, but as September draws to a close it’s time to start protecting tender plants that are not able to withstand winter temperatures.
Stock up on fleecing and bubble wrap, which is ideal for insulating pots and planters, and make sure your protective structures including greenhouses, cold frames and mini greenhouses are clean and in good order.
Greenhouses are busy places in summer, full of tomatoes and more tender crops such as chilies, aubergines, cucumber and melons.
Now those crops will be dying back so remove them and sanitize the growing area. Wipe down surfaces with disinfectant and wash the glass to remove any shading paint applied in summer and allow the maximum amount of light to filter through to overwintering plants.
Fumigating candles are a good way of eradicating pests and the chemicals used in modern ones mean you no longer need to remove plants while they are lit.
Follow the instructions carefully and only return to the greenhouse once the fumes have dispersed.
Your September gardening jobs are also the perfect opportunity to make sure any window panes in your greenhouse are securely in place before the first storms blow through, using more clips to keep them firm.
Top tip: Use a plastic plant label to tease muck and algae from the fiddly gaps between the greenhouse frame and the glass.
8. Take care of houseplants
Don’t neglect your best indoor plants as the days begin to shorten and temperatures drop. Those that have spent summer outside and benefitted from sunlight and cleansing rain showers should be brought back inside now.
Do it gradually so they are not badly affected by a sudden return to drier air and lower light levels. Bring them into a light room or porch for a few nights, returning them outside during the day if the weather stays warm enough, lengthening the time they are inside the house.
Check them for pests, looking for slugs and snails lurking around the pot rims and compost, treating greenfly infestations and saturating the compost with a vine weevil drench. Also deadhead and cut away and old, dead and damaged leaves.
As days grow shorter, it's a good idea to locate your indoor gardens in the lightest areas of the house, making sure that any plants are out of chilly draughts.
Start reducing watering and stop feeding as plants enter dormancy, though this doesn’t apply to any plants that are still flowering.
Top tip: Wiping the leaves with a soft cloth dipped in tepid water or milk keeps leaves glossy and free from dust and pests.
9. Don't forget about lawn care
It is still warm enough for lawns to keep growing, so mow them weekly as one of your September gardening jobs to keep grass at a good length.
Learn how to scarify a lawn by using a rake to give the grass a ‘hair brush’ and dredge out dead grass, moss and weeds and, if soil is compacted in your lawn causing puddles and giving weeds an opportunity to grow, punch holes in the ground with the tines of a garden fork. Both these activities improve airflow and drainage and improve the health of your grass.
Worm casts start to be a problem as the season changes, and these little piles of excreted soil and mucus can create a perfect bed for weeds and moss if they are trodden on.
Leave them alone until they have dried and then brush them away with an old-fashioned broom or the up-ended head of a rake.
Top tip: Fairy rings of toadstools are unsightly but not usually symptomatic of a problem with your lawn. They will be feeding on dead plant material in the soil, possibly old tree roots or other decaying matter and can be scattered with a rake.
10. Look after your pond
Garden ponds are still busy with life in early autumn, though some things are starting to die back and slow down so you do need to make time to carry out some on-going maintenance for your September gardening jobs.
Just as terrestrial garden plants start to fade as summer ends, so aquatic plants reach the end of their annual cycle.
It is important to cut back any dead and dying material to keep your best pond plants tidy and also stop old plant material from falling into the water where it will decompose, absorbing oxygen and releasing toxic gasses.
When you cut back marginal plants, take care not to reduce their stems to below the waterline as they will start to rot, which will kill the plants.
If you have precious ornamental fish or a wildlife pond rich with amphibians, protect them from hungry herons by laying netting over the pond or installing an artificial heron or owl close by.
Netting is also useful for catching falling leaves and preventing them sinking to the bottom and creating a decaying, sludgy layer.
If we have a dry autumn, keep pond levels high. Harvested rainwater is the best, but if you need to use tap water, leave it standing in the watering can for 24 hours first to let chemicals dissipate.
Top tip: A bag of horticultural sand gently poured into your pond will settle on the bottom and create the perfect bed for aquatic invertebrates to hibernate in over winter.
11. Sow green manure
An easy and traditional way of enriching and resting your soil is to sow green manures in autumn. These are members of the rye and legume (bean) families, such as clover and tares, and they are valuable because they help to set nutrients including nitrogen in the soil.
They're a natural way for how to get rid of weeds too as they grow so thickly that weeds can’t get established, plus their roots form mats that prevent soil from being eroded in heavy winter rain.
These plants will grow through autumn and winter into spring, when you can cut them down and dig them in.
If they have grown really thickly, you can cut them back and add the top growth to the compost heap and then dig the stems and roots into the soil. Do this several weeks before you intend to sow or plant ornamental varieties or crops, and the decaying plant material will feed the soil. There's more tips on composting in our dedicated guide, too.
Top tip: If you grew peas or beans this summer, cut down the plants when they have finished cropping but leave the roots in the soil to act as green manure.
12. Take salvia cuttings for new plants
Learning how to take cuttings from plants is such a great way to multiply your blooms without shelling out any extra cash. And it's a lot easier than you think!
Late summer and early autumn is the ideal time for taking cuttings of salvia. Here's how to do it:
- Non-flowering side shoots are the best place to make the cut, just between the leaf and the stem.
- Using a sharp knife make a diagonal cut.
- It's not essential but if you want to speed things up dip the end in rooting powder.
- Have small pots filled with 10cm of fresh compost to hand ready to place the cuttings.
- You can place more than one in each pot but be sure they aren't touching.
- Once new shoots have developed and they look strong and healthy, they can be planted in pots or beds ready for new growth.
There's more tips on how to grow salvias in our guide.
13. Keep things looking tidy with deadheading
You may not get many of your summer blooms repeat flowering at this time of year but by removing dead flowerheads you will help keep your garden borders and pots looking tidy.
Deadheading flowers will also help keep the rest of the plant healthy by saving energy for healthy parts of the plant.
14. Add extra color with paint
If your blooms are lacking at this time of year, then inject some instant color with the best exterior wood paint. Pink is a good choice as it makes a good backdrop to green foliage. Pink and green are opposite on the color wheel so they complement each other well.
Adding paint to your trellis ideas means you will have a bold display to enjoy when your blooms die back too. Do make sure that the paint is fully dry before exposing it to your plants.
15. Keep looking out for pollinators
Don’t forget pollinators when it comes to planning your September gardening jobs as they will still be needing plenty of nectar. If you have any gaps in the border add nectar-rich plants like asters, sedums and echinaceas, which will continue flowering for a few months and re-appear next year.
Also flowering now and pollinator-friendly are ceratostigma willmottianum (blue leadwort), and Japanese anemones in pink or white. Head to our guide to the best bee-friendly plants for more top tips.
16. Pot up some cyclamen for an autumn container
Cyclamen are a great choice for autumn container gardening ideas and they work well combined with evergreen foliage and even herbs.
Add a layer of bubble wrap to the inside edge of your pot before filling with some compost. Arrange your plants and top up with compost so the pot is full. Sprinkle with bark chippings for extra insulation for the colder months.
Ruth is the gardening editor of Amateur Gardening magazine and spends her working days carrying out, writing about and photographing the tasks the readers should be carrying out each week, as well as testing many of the new products that arrive on the gardening market.
She is horticulturally trained, with a qualification from the Royal Horticultural Society, and her work varies with the seasons and includes everything from sowing and planting, to pruning, taking cuttings, dealing with pests and diseases and keeping houseplants healthy. She covers ornamental plants and edible crops and everything she writes about and photographs is in her own garden, a mature plot that has been a work in progress since her family moved to their current house in 2012.
Her main interests are gardening for wildlife and organic gardening, as she firmly believes you don’t need to ‘nuke’ pests and problems with toxic chemicals, nor use peat composts to produce the garden of your dreams.
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