Fabulous plants for September

Here’s a small selection of wonderful plants I’d recommend for the garden in September.  When I drew up the shortlist I hadn’t realised that most of them hold the RHS Award for Garden Merit (AGM), but that just helps to indicate what great plants they are.  No need to just take my word for it!!

Tricyrtis formosana
Such an exotic looking perennial for a shady border.Trycirtis formosana by Firgrove Photographic

The ‘toad lily’ has stunning flowers in August and September and is ideal for a woodland garden with reasonably moist soil.  My own garden is a bit too dry to grow it unfortunately (and I’ve tried a couple of times) so it’s one of those plants I always lust after at this time of year when there aren’t that many perennials which flower this late on in shady conditions.  Tricyrtis gets to about 80cm high and 50cm wide, and will die back over winter.

Aster x frikartii ‘Mönch’ AGM

Aster Monch by Firgrove PhotographicPerfect for the late summer border, this sun-loving lavender-blue perennial looks great with pretty much anything including ornamental grasses.  It grows up to about 90cm tall and about 40cm wide, so may need staking, but otherwise is pretty much trouble free.  Asters generally need fertile soil to do well but this variety can cope with some dryness.  Plant in big groups for maximum effect right into the autumn.

Pontederia cordata AGM
If you have a pond or pool, this is a lovely aquatic plant to grow for its attractive spear-head leaves, and its deep blue spiked flowers in late summer.

Pontederia cordata, Firgrove Photographic

Growing to a height of about 1.2m, it’s a plant which works well if you want something quite architectural either in, or on the margins of, your water.  I particularly enjoy the sight of this plant later in the day when the bright green leaves glow in the evening sun.  It’s a plant that will spread so if space is an issue, plant it in a basket.

Stipa gigantea AGM
Stipa gigantea (or ‘Golden Oat grass’) is a fabulous statement plant for a sunny garden with well-drained soil.  It has an evergreen base of leaves with tall flowering shoots (up to 2.5m high) which glow in the sunshine.  This is a grass that provides height and movement in the border without blocking the view.

Stipa gigantea

It starts to flower as early as May and continues on into autumn so it’s a very valuable plant to include in the garden.  What’s more, you only need to cut back the old stems when they start to collapse, and that’s pretty much it as far as maintenance goes.  Neil Lucas of Knoll Gardens, which specialise in ornamental grasses, particularly recommends the variety ‘Gold Fontaene’.

Eucomis bicolor AGM
This is a bulb with a difference.  Eucomis bicolour is commonly known as ‘two-coloured pineapple lily’, and it’s not that hard to work out why!

Eucomis bicolor by Firgrove Photographic

The flower grows on a spotted stem (about 50cm high) above a low rosette of fleshy leaves, and it adds a bit of a tropical flavour to late summer planting schemes.  Eucomis needs a sunny sheltered spot, and it is generally recommended to mulch it over winter for added protection as it’s on the tender side.  That said, it has survived in my garden (albeit quite sheltered) for years with absolutely no special treatment!

Indigofera Heterantha AGM
This is such an attractive shrub with slender arching branches, delicate foliage and gorgeous deep pink pea flowers which last for weeks and weeks.  I grow it against a fairly sunny fence in dry soil, where it’s tied in to horizontal wires, and it looks lovely.

Indigofera heterantha

It reaches a height of about 2-2.5m, and if grown as a free-standing shrub (with an arching habit) it would spread about the same amount too.  Indigofera lose their leaves in winter, and although a hardy shrub, it can be quite late to come into leaf, but it’s definitely worth the wait.

For details of other plants which are great for this time of year to see, click on the links
Leycesteria Formosa AGM
Dahlia ‘David Howard’ AGM

Picture credits:  Janet Bligh & Firgrove Photographic

Jobs for the productive garden in September

My seasonal tips if you’re growing fruit, vegetables, herbs and flowers for cutting

Keep deadheading annuals and late-flowering Dahlias & Salvias to prolong flowering (and don’t forget to support them as the plants get bigger and top-heavy).

Direct sow hardy annuals (such as Nigella, cornflowers and Calendula officinalis) in to the ground now for early flowers next summer.

Teasels by Firgrove Photographic

Dry seedheads of Eryngium and Teasels to use in flower arrangements.

Tulips by Firgrove Photographic

Order your spring bulbs now if you haven’t done it already – if you leave it too late you may find it hard to get exactly what you want.   If you’re looking for ideas on what to plant, take a look at my blog on choosing bulbs for the cutting garden.

Move tender plants under cover as the night time temperatures drop.

Keep on top of your harvesting to beat damp weather which can damage produce.

Pick sweetcorn as soon as it’s ripe, and if frost is forecast, harvest tender veg. such as courgette, peppers and tomatoes.

Plant out any new strawberry plants now.

Let squash and pumpkins ripen in the sun.

Sow fast-growing oriental greens such as Mizuna and Pak-choi.

Cover leafy vegetable crops with bird-proof netting.

Before slug damage spoils them, dig up any remaining potatoes and store in a cool, frost-free place.


Take up the last of this year’s onion crop and leave them to dry before storing.  You can now sow onion sets to mature next summer.

There’s still time to sow green manures which will release nutrients back in to the soil when they are dug in over spring.

Clean your greenhouse & coldframes to help prevent pests over wintering.

Start to clear up plant debris in borders to keep fungal diseases at bay over winter.

To avoid Vine weevils damaging your plants apply nematodes this month and next, to treat freshly hatched grubs (I get mine from www.ladybirdplantcare.co.uk).


Picture credits:  Janet Bligh & Firgrove Photographic

Jobs for the garden in September

Mid to late September is an ideal time to start autumn planting as the ground is still warm, and plants should be able to establish well before winter kicks in.


Clean your greenhouse & coldframes to help prevent pests over wintering, and move tender plants under cover as the night time temperatures drop.

Treat perennial weeds (such as dandelions and bindweed) with weedkiller  such as Glyphosate, if you can’t dig them out at the roots.

Trim soft growth of ivy, clearing it away from walls, windows and doors (more severe pruning should be carried out in spring).

box balls

Give Box hedging and topiary a final trim before the end of the month (or any likely frost) if you feel the need.

Keep up with deadheading of late flowerers such as Dahlias.

Lift and divide herbaceous perennials which are too big or which need a new lease of life.


Narcissi by Firgrove Photographic

It’s time to think about next year’s spring-flowering bulbs, so if you haven’t already done it, get your orders underway asap.

This is a good time to turn your attention to lawn maintenance.  Reduce the height of the mower as the grass will be slowing in growth and more susceptible to wear.  Scarify and spike the lawn and apply autumn lawn feed, add top dressing particularly if your garden is on clay, chalk or sandy soils.

Repair any bare patches in the lawn by sowing extra grass seed.

Pictorial meadow

This is also a good time to sow a wildflower meadow.   For more information, take a look at our blog about creating meadows.

Net ponds before leaf fall gets underway, and keep water levels topped up if necessary.

Don’t forget to water your pots in dry spells.

If frost if forecast, protect or move more tender plants such as Pelargoniums and Fuchsia.

Continue to deadhead annuals such as Cosmos and Sweet Peas.

Sow hardy annuals in to the ground now for early flowers next summer. This applies to flowers such as Nigella, cornflowers and Calendula officinalis (Marigold).

Start to clear up plant debris in borders to prevent fungal diseases over winter.

To avoid Vine weevils damaging your pot plants in particular (they love to munch plant roots), apply nematodes in September & October to treat freshly hatched grubs (check out www.ladybirdplantcare.co.uk).

NB this information applies to gardens in the UK and you need to take account of your own local weather conditions when carrying out any work in the garden.


Picture credits:  Janet Bligh & Firgrove Photographic

Inspirational summer planting at Pensthorpe Park

I recently took a trip to Pensthorpe Natural Park, a place I’ve been wanting to visit for quite some time.  It’s not that I’m a closet twitcher and fancied a day birdwatching – the reason I wanted to trek to the depths of Norfolk was to see the Millennium Garden, an acre of gorgeous planting designed by renowned Dutch plantsman Piet Oudolf.

Pensthorpe Millennium Garden.JPG

This is a garden designed to look its best in midsummer and late summer, and I’m glad to say that even though I got there relatively early in its peak season, it was worth the trip.

The garden consists of large drifts of plants which create a fantastic tapestry of colour.  No shrubs, just grasses and perennials, so there won’t be much to see in late winter and spring, but in July, August, September and on into autumn, it’s really something.

Echinops Veitchs Blue.JPG

Stunning blue globe thistles Echinops Veitch’s Blue at the garden entrance

Sited next to one of the many lakes in the park, all the way round the garden I could hear the constant hum of insects and, as the paths wind through the borders (occasionally with planting in raised sections) it was a treat to see bees, butterflies and dragonflies up close.

Planting .JPG

I have to admit some of the colour combinations were a bit on the garish side!  They wouldn’t be something I’d recreate at home or for my clients (I don’t think), but somehow in that setting, and I think crucially, at that scale, they worked.

Helenium 'Rubinzwerg'.  A very colourful combination!

Phlox ‘Dusterlohe’ and Helenium ‘Rubinzwerg’. A very colourful combination!

Shocking pink Phlox and a deep orange red Helenium certainly wouldn’t be everyone’s cup of tea, but I thought they looked great (from a distance at any rate!) and really provided a vibrant splash of colour.

Astilbe 'Purpurlanze'

A splash of purple from Astilbe ‘Purpurlanze’ in the foreground

The soil at Pensthorpe is quite poor, and of course Norfolk is a very dry part of the UK, but the Millennium Garden is irrigated, so plants which you wouldn’t normally expect to thrive in that environment (for example Actaea, Lythrum, Monarda, Persicaria) were doing well side by side more drought tolerant plants such as Nepeta, Sedum and Origanum.


This type of naturalistic planting is all the rage at the moment, and there are many other gardens to visit where you can see other examples.  (Check out Gardens to visit in late summer & early autumn).

Although I’m ashamed to say I struggle to tell the difference between a Moorhen and a Coot, I did enjoy being surrounded by so many birds (whatever they were!!) as I wandered around the park.


I took a walk over to the Wildflower Meadow which although past its best visually, was literally humming with insect activity, and is an important habitat for dragonflies, butterflies and demoiselle damselflies.

Plants along the stream in the Wildlife Habitat Garden

Plants along the stream in the Wildlife Habitat Garden

Pensthorpe also has a Wildlife Habitat Garden which has been planted with species to attract insects and mammals. Running water and a variety of nesting boxes also help to make this a fantastic wildlife-friendly environment.  It’s a great place to pick up ideas – as well as a visual feast at this time of year.

Pensthorpe Natural Park


Picture credits:  Janet Bligh