6 plants to cut back in August for an extra flush of flowers – trim these varieties now for bonus blooms

We might be nearing the end of summer, but that doesn’t mean your plants’ glory days are over. In fact, there are some plants you can cut back in August for an extra flush of flowers.

Perennials, specifically. They rank high on a list of plants to prune in August, because they respond really well to a trim at this time of the year. Cutting them back could even reward you with a bonus round of blooms, according to experts.

‘August is the point when many gardens begin to look slightly tired, but cutting the right plants back can encourage a completely fresh flush of foliage and flowers,’ says Jane Westoby, creative director at The Hampshire Seed Company. ‘The key is to cut decisively rather than simply removing the occasional faded bloom.

Below, you’ll find a few examples of plants to cut back in August for an extra flush of flowers.

What you'll need

1. Hardy geraniums

As the name would have it, hardy geraniums are tough perennials that produce lots and lots of pretty blooms. They’re also fantastic ground cover plants that can block weeds, but this late in the season, they’ll likely be starting to look a little messy. That’s where a pair of snips will come in handy – and even encourage extra flowers.

‘Hardy geraniums can become sprawling and untidy after their first flowering,’ says Jane. ‘Cut the stems and tired foliage back close to the base, water them thoroughly, and they will usually produce fresh leaves followed by another flush of flowers.’

If you’re looking for the best secateurs for the job, it’s worth going for bypass secateurs, which are better suited to cleanly cutting the stems. These Spear & Jackson Razorsharp Advantage Bypass Secateurs are just £10.95 at Amazon, and one of my favourite pairs to date.

2. Lady's mantle

Lady’s mantle, or Alchemilla mollis, is one of the best cottage garden plants for pots, because it's so pretty. It's another perennial that responds well to light pruning in late summer.

‘In August, the perennials worth cutting back are the ones that have finished their first flower flush and are willing to repeat,’ says Julian Palphramand, head of plants at British Garden Centres. ‘Lady’s mantle will often respond well to a trim, especially if you remove spent flower stems and any tired growth.’

If you want to use a premium pair of snips, the Niwaki Garden Snips are the best I’ve tried.

3. Penstemons

Penstemons benefit from a trim in August as well, but they're best treated lightly if you want them to survive the colder months. A compact pair of snips like these Kent & Stowe Garden Life Pruning Snips from B&Q are ideal for smaller tasks.

'Keep removing faded flower stems, cutting back to a healthy sideshoot rather than trimming the whole plant indiscriminately,' advises Jane. 'This encourages more flowers while leaving enough protective growth on the plant for winter.'

It's almost time to take cuttings from your penstemons, too, since they're one of the best plants you can propagate in September.

4. Delphiniums

You don't have to say goodbye to those stately flower spikes just yet – according to Julian, delphiniums are another plant you should cut back in August for an extra flush of flowers.

'A light cut-back now can tidy the plant and encourage fresh growth that may carry a second round of flowers later in the season,' he says.

Aftercare is just as important as the pruning task itself, and it'll determine how well your plants recover.

'One important caveat is that plants need water to regrow,' explains Jane. 'Cutting them back during very hot or dry weather without watering them afterwards can place them under even more stress. A thorough soak is often more useful than immediately adding fertiliser.'

5. Catmint

Catmint is a beautiful perennial, and it's also a low-maintenance flowering plant that can keep mosquitoes at bay. To encourage the plant to flower again, it's worth cutting it back hard in August.

'Once catmint begins to flop and fade, shear the whole plant back rather than deadheading individual stems,' advises Jane. 'Give it a good drink afterwards and it should quickly form a neat mound of fresh growth and more flowers.'

I also rate the WOLF-Garten Bypass Secateurs, available at Amazon, if you're looking for a sturdy pair of pruners.

6. Perennial salvias

Last but not least, perennial salvias also benefit from a trim in August – especially if you want them to flower for the remainder of the growing season. If you're wondering how to prune salvias at this time of the year, it's best to take a lighter approach.

'Remove faded flower stems by cutting them back to a healthy pair of leaves or a sideshoot lower down the stem,' says Jane. 'Regular cutting prevents the plants putting energy into seed production and can keep many salvias flowering well into autumn.'

Cut these plants back in August for a bonus round of blooms. It's a task worth doing!