August is the official last month of summer, which makes it the perfect time to make the most of your garden while it’s still looking its best.

The list of gardening jobs in August will typically be shorter than in other months, but there are still plenty of ongoing tasks to perform that’ll help your garden thrive. 

From deadheading flowering plants to repotting well-rooted strawberry runners, here are 15 garden tasks to focus on this month.

1. Deadhead flowering plants

Deadheading is the act of removing any dead flower heads from your plants. It’s important to do this regularly during late summer if you want your plants to continue flowering into autumn. Examples of plants that can continue looking beautiful into September and October include dahlias, roses, and penstemon.

Deadheading is also a good way to stop self-seeding plants like gladioli and alliums from spreading. If dead flower heads are left in place, some will scatter seeds and you’ll end up with lots of plants popping up in new areas next spring. 

It’s easy for self-seeding plants to get out of control without regular deadheading, and you might have to spend more time clearing space in your garden that you weren’t really looking to fill.

2. Prune wisteria

Trimming back your wisteria a couple of months after it’s flowered in late summer will encourage new flowers and control its growth.

It’s best to cut back new growth to about five or six leaves from the base. This will encourage a new flowering spurt in the autumn and also prevent your wisteria from growing into gutters and windows. It can ramble unchecked if you let it.

This helpful guide from BBC Gardeners’ World will teach you more about how and when to prune wisteria.

3. Cut back herbs

Herbs have a tendency to grow and spread pretty quickly, but it’s best to keep them pruned back in the summer to help them stay hydrated. It’s much easier for the roots to deliver water to shorter stems.

Some hardy herbs like mint and thyme will survive the winter but will stop growing in the winter when they become dormant – while others like fennel and oregano will typically die off until next spring. So, by trimming your herbs back in later summer, you’ll also encourage a new batch of fresh leaves (that usually taste the best!) that you can harvest before the frost arrives. 

Consider drying or freezing herbs when you harvest them for use in the kitchen later on. Have a look at this useful guide from Grow Veg to find out more about how to preserve and store your fresh herbs.

4. Collect seeds from plants and store them for next year

While deadheading allows you to stay in control of your garden and encourage new flowers, leaving some seed heads in place can actually look quite attractive. It can also allow you to collect and save the seeds before they fall naturally. 

Depending on the type of seeds, some will want to be sown in late autumn, while others might want to be stored in a cool, dry place until early spring. Why not take a look at our planting calendar, which will show you the best months to sow seeds for different types of flowers and vegetables? Sowing seeds is a great way to plan ahead while saving some money on buying new plants or seeds.

The RHS offers a useful guide that has more information about how to collect and store seeds. The video below will also show you how to collect seeds from dahlias.

5. Prune rambling roses

Although beautiful, if rambling or climbing roses aren’t maintained, their stems can become tangled. This will affect how well they flower and leave them more open to disease. Pruning them in late summer allows for better air circulation, keeps them healthy, and will usually improve their performance the following year.

To prune your rambling rose, cut off any dead, dying, or diseased leaves, shoots, stumps, or stems. You can also use this opportunity to remove any branches that are growing awkwardly or ruining the shape of the plant.

For more information about how to prune a rambling rose, check out this RHS guide.

6. Harvest fruit and vegetables as they become ready

August is a great month for picking plenty of fruit and vegetables from plants and trees. Tomatoes, cucumbers, and plums are examples of some of the many ingredients in nature’s kitchen that could be ripe and ready for you to enjoy.

If you’d like to know more about what to pick and when, have a look at this harvesting guide from Waitrose.

7. Look after your water features

With August often being one of the hottest months of the year, water features like ponds and birdbaths can dry out much faster than usual. This means that it’s a good idea to check their water levels at least twice a week, so you can keep them topped up.

Just like watering holes in the Savannah, you may be surprised at what a haven for wildlife these water sources can become. Plus, when water features become shallow, they can turn green pretty quickly.

Birdbaths can be easily scrubbed, cleaned, and given a water change if this happens. During the summer months, it’s especially important to check on your birdbath’s water level because – even if you don’t see it being used – you might be surprised how many visitors it has when you’re not looking! Take a look at the footage below to see how different birds could be using your birdbath.

With ponds, you can remove any algae, blanket, or duckweed from the surface with a net or skimmer. You could also consider adding some aquatic plants like lily pads or watercress – you can usually find these at your local garden centre

These plants draw up nutrients from the water, making it much harder for algae to grow.

For best results, you’ll usually need to cover 60% of your pond’s surface with aquatic plants. To find out more about how to avoid algae and blanketweed in your pond, have a read of this RHS guide.

8. Look out for potato and tomato blight

The summer months of July and August are typically when your tomatoes and potatoes are most likely to suffer from blight because the weather is warmer and more humid. 

Blight is a fungal infection that’s carried by insects, wind, and water. It infects and spreads quickly through tomato and potato foliage, and can kill a plant within a week. It causes leaves to become discoloured, and some will also rot and collapse. Once the blight has spread to the vegetables, they’ll be rendered inedible and need to be disposed of.

You can’t cure blight, so prevention is your best course of action. You can protect your potatoes and tomatoes by growing them in dry, sunny, well-ventilated spots.

You can also slow down the spread of the infection and harvest what vegetables you can before it spreads too far. 

To find out more about how to avoid and control blight, check out this article from BBC Gardeners’ World Magazine.

9. Keep plants hydrated as best you can

July and August are typically the two hottest months of the year, so, if you can, try to keep your plants as hydrated as possible. Plants, like camellias, rhododendrons, and sunflowers will often need extra watering during the late summer months, while their flower buds are forming.

It’s best to water your plants either first thing in the morning or late at night, rather than during the hottest part of the day. Make sure you give them a good soaking for at least 20 seconds.

If you’re planning on going away on holiday in August, consider asking a friend, family member, or neighbour to water your garden for you every couple of days. And make sure that you give them a good soaking before you go (the plants, not the friend or family member!).

Although, if you live in Kent or Sussex, please remember that there are currently hosepipe bans in place, so make sure to adhere to these guidelines when watering the plants in your garden. And if you live elsewhere, always try to use water sparingly especially, during dry months – lawns, in particular, will usually bounce back when the autumn rain comes.

You could also consider getting a waterbutt that fills up off the house gutter system to reuse as much rainwater as you can – the summer could be a great time to install one ready for the autumn rain….

10. Re-pot well-rooted strawberry runners

During the summer, strawberry plants will produce ‘runners’ as a means of propagating themselves. These runners are essentially long horizontal stems that run along the surface of the soil and produce new plants at intervals. If your strawberry plant is growing in a pot, it’ll still grow runners, which will look like long arms hanging out of the pot.

Once runners have grown young plants and they develop established roots, you can place each one in its own pot. When they have settled into their new pots, just snip the stem that connects them to the parent plant.

If you want to find out more about how strawberry runners work and how you can propagate new plants from them, read this guide from BBC Gardeners’ World Magazine or watch the video below.

11. Give hedges one last trim before they stop growing

If you’ve been meaning to trim your hedge, but haven’t gotten around to it yet, now could be the perfect time to do it. Different hedges have different needs, but, generally speaking, pruning your hedge in late summer will allow any bald patches to recover before it becomes dormant in winter.

Your hedge is much more likely to hold its shape until next year if you trim it in August. This is because it’ll probably experience a little bit of new growth that’ll help to flesh it out and add to its shape, but it won’t have time to get too unruly before the cold weather arrives.

For more detailed guidance on how and when to trim your hedge, check out this guide from the RHS.

12. Feed perennials and container plants

If you’d like border perennials (plants that live for more than two years) or container plants to continue flowering into the early autumn, it’s a good idea to water them with a liquid fertilizer once a fortnight.

You can get hold of liquid fertilizers quite cheaply at your local B&Q, Homebase, or on Amazon.

13. Mow your lawn regularly

It’s a good idea to mow your lawn regularly in August to create short grass clippings. If you leave these clippings on the lawn, they can help to retain water and keep your lawn hydrated.

If your lawn is looking a little brown this month, try not to worry and avoid watering it unless absolutely necessary – it’ll bounce back once the autumn rain arrives.

Weedkillers are also more effective on lawns when used in damper, cooler weather. So, again, try to wait until the autumn to use them if possible, or simply pull weeds up by hand.

14. Consider planting something new

Just because August is the last month of summer, this doesn’t mean that you can’t introduce some new plants to your garden.

Marigolds are a great option and will continue to flower until the weather gets really frosty. They look lovely in the autumn – especially if you’re planning to decorate your garden with pumpkins for Halloween. 

August is also a great time to allow black-eyed Susans to establish roots in the ground. Then, when they die out, they’ll hopefully come back next year and last from early summer right through to autumn. Cucumbers can also grow to a ripe and ready size in 40 days, so if you pick and plant the seeds now, they could be ready to harvest by the fall.

To find out what else you could plant in your garden this month, take a look at this article from House Beautiful.

15. Keep on top of weeds

Weeds will compete with your plants for nutrients and could slow their growth. Weeds – like bindweed – can also strangle your plants and eventually kill them. Bindweed spreads fast, so it’s best to nip it in the bud before it gets out of control.

To keep weeds at bay, you can hoe your flower bed regularly and/or pull up weeds by hand. You can also use hot or boiling water (rather than pesticides) to kill weeds in between paving slabs if your patio is looking untidy.

To find out more about how to control weeds without using chemicals, have a look at this guide from the RHS.

Final thoughts...

From dead-heading flowering plants to giving your water features some long overdue TLC, there’s plenty you can be getting on with in your garden during August.

For more gardening tips and tricks, including some advice on how to get stuck into green-fingered activities indoors or on a balcony, why not head over to the home and garden section of our website?