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


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

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

Fabulous plants for August

Let’s face it, a lot of gardens start to get a bit boring in midsummer, so if you’re looking for colour and interest for August, here’s a small selection of my favourite plants.

Hydrangea arborescens ‘Annabelle’
I’m not sure why, but Hydrangeas often appear on my clients’ ‘Don’t Like’ lists.  Maybe it’s the old-fashioned image and big blowsy flowers that does it.  But even the most hardened Hydrangea haters seem to fall for the lovely ‘Annabelle’.

Hydrangea Annabelle credit  Firgrove Photographic

Hydrangea arborescens ‘Annabelle’

I guess it’s the classic green and white combination, and the sheer size of the flower heads that wins them over.  They certainly make a real statement (the plants can reach over 6’ in height and spread, and the flower heads can get to as much as 10” in diameter!).

In an ideal world this variety of Hydrangea wants to be planted in moist but well-drained soil, with sun or partial shade.  They will grow in drier situations but the growth won’t be as vigorous and the flower heads won’t be as enormous – but that can be an advantage as often their weight makes the supporting stems flop over.  Top tip (wherever you grow them) – make sure you put in adequate support for the plants at the start of the season – that way you’ll avoid the stems getting damaged later on, and you’ll get to enjoy the plant in all its glory.  The flowers fade to lime green and the dark green foliage turns yellow in autumn, so it’s a great plant for mid- and late-summer interest.

Perovskia atriplicifolia
Perovskia, commonly known as ‘Russian Sage’ is technically known as a sub-shrub, as it grows from a woody base. This is a plant that thrives in hot sunny borders with well-drained soil and it’s always a very welcome sight in midsummer which can be a difficult time to find colour in the garden – the early flowers are over and the later autumn flowering plants aren’t quite at their best yet.

Perovskia 'Blue Spire' at RHS Wisley Gardens

Perovskia ‘Blue Spire’ at RHS Wisley Gardens, Surrey

To succeed with Perovskia, you should prune plants in late spring when they are starting to put on growth, rather than cutting back in autumn. You’ll then be rewarded with upright silvery grey stems with fragrant leaves and lovely violet flowers in late summer.  The best known Perovskia is probably ‘Blue Spire’ which reaches 1m in height, but I also use ‘Little Spire’ which as the name suggests is a smaller variety, reaching 60-80cm in height as a rule. For maximum impact, grow them in groups.

Geranium Rozanne ‘Gerwat’
This is one of those really long-flowering perennials I seem to include in pretty much every garden I plant!  I’m always looking for reliable, great value plants and this particular hardy Geranium is invaluable.

Geranium 'Rozanne'

Geranium ‘Rozanne’

No kidding, it flowers from June to October or even into November, and there aren’t that many reliable plants that can offer that sort of flowering period!
It’s fast-growing and spreading (up to 1 metre wide), forming a wide clump of foliage which is great to smother weeds, and its large blue flowers are held on stems above the mound of leaves.  Fine in sun or some shade, not fussy about soil type and generally very easy to grow.   Hardly surprising Geranium Rozanne was named ‘Plant of the Centenary’ at the RHS Chelsea Flower Show 2013!

Lythrum salicaria ‘Robert’
This ‘loosestrife’ is another long-flowering perennial which provides a real splash of colour in midsummer, and will attract lots of insects in search of nectar, so it’s great if you’re interested in planting for wildlife.

Lythrum salicaria 'Robert'

Brilliant colour from Lythrum salicaria ‘Robert’

Flowering from July to September Lythrum ‘Robert’ has dense upright spikes of deep pink flowers and reaches about 75cm in height.  It will grow in some shade, but Lythrums do need a reasonable amount of moisture in the soil to thrive.  In fact most Lythrums are ideal for bog gardens and to grow as marginal plants next to water. ‘Robert’ though, is alleged to be more tolerant of slightly drier conditions than other Lythrums and I have grown it successfully in the garden above, which has fairly water-retentive soil but is far from being classed as boggy.

Lythrum Feuerkerze

Lythrum salicaria ‘Feuerkerze’ AGM

A slightly taller variety is the reliable Lythrum salicaria ‘Feuerkerze’ AGM (Award of Garden Merit from the RHS).  It gets to about 90cm high and about 45cm wide, so all in all a slightly larger variety than ‘Robert’.

Clematis viticella ‘Venosa Violacea’ AGM
This is a very easy two tone purple Clematis which will tolerate some shade and isn’t too fussy about soil conditions.  Flowering from July to September and reaching up to about 3 metres in height, it’s great to climb up trees and scramble through shrubs which have finished flowering and could do with a bit of extra colour at this time of year.

Clematis venosa 'Violacea' AGM

Clematis venosa ‘Violacea’ AGM

It’s not so big that it will get out of control and is such a good plant it’s been awarded the RHS Award of Garden Merit.

Eryngium giganteum ‘Silver Ghost’ AGM
Eryngium (or ‘sea hollies’) are great plants for dry sunny gardens with poor soil, where they will thrive.

Eryngium Silver Ghost, Perovskia, Echinacea

Great planting combinations at RHS Wisley – Eryngium ‘Silver Ghost, Perovskia and Echinacea

They look fantastic with grasses and plants like Lavender, Perovskia and Nepeta which like similar conditions.  But they are not only valuable for the fact that they will grow where many other plants won’t, but because they offer such a long season of interest, having a beautiful architectural form which lasts long in to the winter.  There are many varieties of Eryngium, and ‘Silver Ghost’ is a biennial (which means it flowers in its second year and then dies after setting seed).  The flowers turn blue as they mature and can be dried for flower arranging.

Eryngium 'Silver Ghost'

Eryngium ‘Silver Ghost’

Many other Eryngiums are perennial and it’s worth growing a mix of varieties for different flower forms, heights, and shades of blue and silver – if you have the right conditions in your garden.

Picture credits: Janet Bligh & Firgrove Photographic