Gardening Jobs for September

This month we say goodbye to summer and welcome autumn in, with its wheelbarrow full of tidy-up tasks and more. There are plenty of garden jobs in September, from revitalising your lawn to pruning the right plants and flowers and keeping on top of your kitchen garden, which is still producing a bounty of crops to harvest. Read this month's advice from our Garden Guru, Rich.

Jobs to Do in the Garden in September

In this guide we’ll take you through what to plant in September, how to care for your flowers, plants and trees this month and lots of other tips and tricks to get your garden looking glorious for autumn.  Let’s start with our top tip…

Top Garden Tip for September – Get Your Lawn Lush and Green

Give a new lease of life to your lawn by firstly raking up any debris on it with a rake. Next, aerate the ground by sticking a garden fork into it every 15cm. Then scatter a top dressing (a special mix of soil, sand and nutrients) over the surface, working it into the holes with a stiff broom.

Jobs for Beds and Borders

Deadhead your herbaceous plants frequently to keep them looking their best and cut back those that have begun to overgrow, unless you want to keep them as they are for their winter seed heads.

Trim mounds of Alchemilla Mollis, tall hardy geraniums and peonies to remove old, diseased or scruffy foliage. This will encourage new growth to soon appear.

Tips for Trees and Shrubs

Cast your eye over tree ties and stakes. Tighten any that are loose and relax ties that are digging into stems. As a general rule, you should only need stakes to support a tree for 18 months before being removed.

Plant heather in soil enriched with composted bark or well-rotted leaf mould. Read our guide on how to make leaf mould - it's an easy (and free!) way to make a nutrient-rich mulch for your borders and pots. 

Keep powdery mildew on roses under control by spraying shoots covered in the white fungal growth with fungicide. Stop the disease coming back by making sure soil doesn’t dry out and mulching to keep moisture in.

Spray ornamental cherry trees with a fungicide to control shot hole disease. You can tell what it is when you see brown spots appearing on leaves which expand and then fall out, leaving holes in the foliage, hence the curious name.

Tidy up Jerusalem sage (Phlomis Fruticosa) by removing dead flowers and thinning out older shoots.

Growth of evergreen hedges will soon slow, so now is the time to give them one last trim to keep them looking neat until springtime. If you’re not sure how to trim hedges, read our guide – it details everything you need to know. 

Prune lavender plants slightly with a pair of shears once they’ve come to the end of their flowering season to remove dead blooms. Trim again in spring, removing around an inch of growth. Read our guide on how to prune lavender for some top advice from our Garden Guru, Rich.

Scatter a 7.5cm layer of leaf mould, manure or garden compost around rhododendrons and azaleas.

Get the earth ready for planting fresh roses. Dig over the soil, get rid of perennial weeds and spread lots of garden compost, manure, or another well-rotted, organic material over the area.

Kitchen Garden Jobs and What to Plant in September

What should you harvest this month? What plants can you plant in September? We may be leaving summer behind but there’s still plenty to do in the kitchen garden. 

Keep an eye on apple and pear trees and harvest the fruit when it can be twisted off the stems easily.

Prevent apple and pear tree leaves from being eaten away by winter moth caterpillars by wrapping the trunks in sticky bands. This will stop female moths from crawling into the branches to lay their eggs.

Neaten up gooseberry and blackberry bushes by snipping off mildew-infected shoot tips and cutting canes that fruited this year down to ground level. Select the strongest new shoots and tie to canes or other supports.

Prevent the frost from stealing your final tomatoes – cut off whole bunches of unripe fruit and keep indoors away from direct sunlight. In a week or so they should ripen and redden.

Cut asparagus to 5cm away from ground level when the ferny leaves start yellowing.

Plant out spring cabbages 15cm apart in rows 30cm apart. Cover with fine mesh or fleece to stop birds harvesting the leaves for themselves.

Sow seeds of early carrots such as ‘Amsterdam Forcing’ and ‘Early Nantes’ nice and deep, about 6cm in the ground. Keep them protected from the cold by covering them with a cloche for harvesting early next year. If you have a greenhouse, you could grow them in containers here instead. 

Plant strawberries in weed-free soil. Fertilise the soil in advance by mixing in some well-rotted farmyard manure to help your fruits thrive. 

Make sure Brussels sprouts are tied to supports to stop them being thrown over by strong winds and remove any yellowing leaves.

Undercover September Jobs in the Garden

Clean shade paint off greenhouses or remove sheets of netting so that maximum light reaches the plants inside.

Make sure greenhouse heaters are in good working order ahead of first frosts and replace them if necessary.

If you put any houseplants outside for the summer, bring them back in so they don’t suffer in colder weather. Pick off spent leaves and blooms and inspect for signs of pests. Read our guide on how to care for houseplants if you’re not sure how best to look after them in the coming months. 

When the weather starts to turn a bit cooler, shut greenhouse vents, doors and windows after dusk to retain heat overnight. Open them up in the morning so as to avoid a build-up of heat gained during daylight hours.

Once you’ve done all your garden jobs for September, your outdoor space will be looking tidier and will keep on being as productive as possible. So prepare to reap the rewards of a beautiful garden and all the crops and flowers it produces.