September in the Garden

Many of us have had a depressingly wet and chilly August, and while a bit of rain is good for the garden and does keep everything going a bit longer, I do feel sorry for all those families away in the UK in the school holidays. September seems to be starting well though, so let’s hope we’re going to get an Indian summer!

Our Top Ten Flowering Plants for September: 

image of Anemone japonica ‘Whirlwind’

Anemone japonica ‘Whirlwind’

A tallish plant for the middle of the border with double white flowers with a yellow centre, August – October. The great thing is, it will grow quite happily in partial shade.

image of Ceanothus ‘Autumnal Blue’

Ceanothus ‘Autumnal Blue’

A colour that’s hard to find in the late summer border, sky-blue flowers make this shrub a valuable addition to the garden. It is evergreen and can grow quite tall as well as needing some protection, so grow it if you have the space and a sunny fence or wall to cover.

image of Clematis texenensis ‘Princess Diana’

Clematis texenensis ‘Princess Diana’

A slightly unusual variety from North America, this climber has large, pendulous, tulip-shaped deep pink flowers over a long flowering season. Prune it in the early spring by cutting back to pairs of plump buds about 75cms above soil level.

image of Echinacea ‘Prairie Splendor’

Echinacea ‘Prairie Splendor’

A bold daisy-like, deep pink flower with a prominent central cone. Looks good with grasses in a ‘prairie’ scheme, as the name suggests, but just as good in a traditional cottage style garden.

image of Hibiscus syriacus ‘Blue Bird’

Hibiscus syriacus ‘Blue Bird’

A deciduous shrub for a sunny border with an abundance of large, saucer-shaped, deep violet-blue flowers July – October. Don’t worry if this shrub seems late to wake up in the spring – the leaves don’t appear until well after most other things in the garden. 

image of Kniphofia caulescens

Kniphofia caulescens

A tall, evergreen variety of the familiar ‘Red Hot Poker’ with stout stems and fat spikes of coral-red to yellow flowers. The grey-green leaves stay on the plant all year round. 

image of Liatris spicata ‘Kobold’

Liatris spicata ‘Kobold’

Another plant originating from America, this perennial has spikes of mauve, bottle-brush-like flowers, unusual in that, unlike most other plants, the flowers open from the top of the spike downwards, instead of the other way round. Looks good in a meadow planting scheme, as well as in the mixed border. We used it in our medal winning garden at Hampton Court.

image of Lobelia cardinalis ‘Queen Victoria’

Lobelia cardinalis ‘Queen Victoria’

A really striking upright perennial which would look fabulous in an exotic scheme, it has deep purple foliage contrasting dramatically with it’s spikes of bright red flowers.

image of Rudbeckia fulgida ‘Goldsturm’

Rudbeckia fulgida ‘Goldsturm’

Another easy-to-grow daisy-like flower, this time yellow, with a prominent dark centre September – October. A really cheerful addition to the late summer border.

image of Verbena bonariensis

Verbena bonariensis

A really pretty perennial for the back of the border with tall airy stems and small mauve flowers all summer long.

September Tip and Advice:  

1. Continue your routine jobs of dead-heading, weeding and generally tidying up. 

2. If you’re planning new borders for next year, now is a good time to start preparing by digging over to at least a depth of 50cms and adding plenty of good compost or manure. Then finalise your planting plan ready for planting out next month. 

3. Perennials that flowered earlier in the year can be lifted and divided now. This not only revitalises the plants, but also provides you with lots more plants for free! 

4. You can also sow hardy annuals now in the ground where they are to flower next year – you’ll have stronger plants and earlier flowering. These include Calendula (pot marigolds), Centaurea (cornflowers), Eschscholzia (californian poppy), Iberis (candytuft), Nigella (love-in-a-mist) and Papaver rhoeas (annual poppy). 

5. Cuttings can be taken now of any shrubs whose hardiness is questionable as an insurance against loss. They will need to be put in the greenhouse or in a cold frame for the winter.  

6. Root-balled evergreens may be planted towards the end of the month. These can be much cheaper than container-grown plants so it’s worth shopping around. 

7. Continue to check for pests and diseases, especially on roses, and treat as necessary. 

8. Rambling roses can be pruned now, ideally cutting out all the old wood and leaving strong new stems which you can tie back in to supports. 

9. If you have Wisteria, early this month, shorten the long, whippy shoots to about 30cms from their source.  

10. Finally, if you have a greenhouse, now is the time to think about getting it ready for winter – many of your plants will need to be brought inside before the end of the month. Give it a good clean up and ensure any heating equipment is working properly. 

By Helen Ellison, Garden Designer

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