Adding late-summer colour and planning ahead

WRITTEN BY SOPHIE VALENTINE

September is a beautiful month in the garden.  Warm sunny days, glowing golden evenings (with the occasional downpour, and gust of wind), flowers in full bloom, and wild borders bursting with colour and pollinators. For beginner gardeners, this is a perfect time to learn, experiment, and enjoy your space. Whether you’re at the beginning of your garden journey, slowly filling it up or maintaining your full garden there’s still so much to do this month and plenty to look forward to!

I wanted to show you some things which are looking beautiful in my garden right now and give you a few ideas of things you can be doing in your garden this month to make the most of this late-summer period to keep your garden looking full and colourful right through into autumn.

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What’s looking nice in my garden now

The good news is that they don’t only look good in my garden now, it is the perfect time to be planting them in your garden.

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Deadheading, feeding & maintenance

By September, many summer flowering perennials and annuals are in full bloom.  You might also have some earlier flowering perennials that have already been flowering for months and need a tidy up and a feed ready for another flourish. 

This is your cue to deadhead your repeat flowering perennials and annuals regularly.  Simply snip or pinch off spent flowers to encourage more blooms and prevent the plant from putting energy into seed production.  I like to do this every week on a Friday after work.  I head into the garden with a cup of tea and a large bucket and I really enjoy this time.

Deadheading is especially important for annuals like cosmos, zinnias, and calendula, which can flower until the first frosts if cared for properly. Make sure you are also regularly cutting your cut and come again flowers like Dahlias to promote more flowers.

While you’re at it, give your plants a light liquid feed every couple of weeks. This is especially helpful for container plants and hanging baskets, which can quickly use up nutrients. Look for an all-purpose feed or one high in potash (like Tomato feed) to really boost flower production.
Don’t forget while you are deadheading and feeding make sure you:

• Trim back any overgrown plants crowding others.
• Keep an eye on watering, especially during dry spells.  Pots can dry out quickly, give them a long deep soak a couple of times a week.  Even if we have had rain often the pots don’t get as much water as you think.
• Check for pests like aphids and caterpillars and earwigs!

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Pruning and tidying up

September is a great time for light pruning, especially for plants that have already finished flowering. For example:

• Lavender can be trimmed back once its flowers fade — just avoid cutting into old wood.
• Shrubby herbs like thyme, oregano, and sage can be neatened up.
• Perennials like hardy geraniums, nepeta or alchemilla mollis can be cut back to encourage fresh foliage.

If you’ve got flowering shrubs like roses, remove any dead or diseased stems and continue deadheading.

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Add late summer colour & texture

Now is the perfect time to refresh tired borders and add splashes of colour that will carry your garden into autumn. Look for plants that will flower well into October, especially late-flowering perennials and ornamental grasses.

• Stipa tenuissima (Mexican feather grass)
• Pennisetum (fountain grass)
• Miscanthus sinensis

These pair beautifully with bold late-summer flowers like Echinacea and Salvia and look wonderful as the light changes in autumn.

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10 Perennials to plant now for autumn colour

If you’re happy to invest in a few perennials now here are 10 brilliant choices that will give you colour this autumn:

• Rudbeckia  – Bring on the summer heat with the hues of dusky reds and maroons coupled with ambers and dusky oranges.  Flowering Jul-Oct
• Echinacea – Primrose have lots of varieties available in tones of pinks and peaches in both 9cm and 2litre pots. 
• Helenium – Fiery red-orange and yellow flowers, great for warm borders. Flowering into September.
• Sedum – Succulent foliage and flowers in shades of pink and white they are such a valuable plant for both borders and containers. Some varieties flowering as late as November. 
• Aster – Masses of lavender-blue or pink flowers which will bloom well into Autumn.  Shorter and taller varieties available to fill your borders.  
• Salvia ‘Amistad’ – Loved by the pollinators this giant salvia is a must have for borders and containers.  Flowers July-Nov 
• Geranium Rozanne – If you haven’t already got this plant you need it.  Flowers from June all the way to October
• Verbena bonariensis – Tall, airy, and brilliant for attracting butterflies. Flowers Jun-Oct
• Erigeron Karvinskianus – Beautiful little daisies that require no effort and flower from Jun-Oct
• Japanese anemone  – Elegant white blooms into autumn. Flowering Aug-Oct

All of these perennials are relatively low-maintenance and will come back year after year, getting bigger and better with time.

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