September Gardening – What To Do in the Garden in September

“But now in September the garden has cooled… The sun warms my back instead of beating on my head.” After all that intense heat and sunshine during July and August in the UK, it’s really rather a relief to be thinking about September gardening now. And I didn’t post a garden update in August as I took most of that month off for holidays – one of the perks of being a freelancer! However, normal service has now resumed, so welcome to September’s horticultural update, let’s take a look at what to do in the garden this month.

What to do in the garden in September

Although I didn’t publish a garden blog round up for August, I shared some of the floral beauties that graced our August garden in this Instagram post. But back to September, and as I always do, I’ll split this month’s round up into sections: flowers, vegetables, jobs, and wildlife, not forgetting a dash of September gardening tips and suggested jobs to do in the garden.

September garden flowers – flowers that bloom in September

You may recall I first broke things down into annuals, perennials, wildflowers, and edibles in July’s garden update. I think it worked well and made things easier to read, so I’m keeping that format for our flowers from now on.

Annuals

Just to recap, annuals are plants that grow from seed, flower, set seed, and then die, all within one year. First up is my beautiful Cosmos Lemonade in a pot by our front door. I keep dead heading and she keeps blooming. We also have lots of late summer bedding purple Petunias in our herbaceous borders, whose seeds only now do I remember broadcast sowing earlier this year. Tip: “broadcast sowing” is the technical term for chucking seed down any old where when you’re fed up with seed trays and pots 🙂

I’m so thrilled that one of my purple Cobea Scandens vines* sown from seed this February has put out her first bloom. Fun fact: she’s also known as the cup-and-saucer vine, because if you tilt up the flowers, they look just like a china tea cup. As vines, they need plenty of support to grow, so a wall with some wires or a trellis fence is best.

September gardening sees our Cornflowers* still growing strongly, helped by some daily dead heading to encourage new blooms. And the self-sown Claret Sunflowers* in one of our veg beds are still providing late summer nectar to the bees.

Perennials

Again, just to recap, perennial plants and shrubs are those that come back every year – and they tend to be low maintenance, good value garden essentials, so we have a LOT of them 🙂 Technically, bulbs and corms aren’t perennials, but heigh ho. So, first up with September gardening colour are our dahlias. Our stalwart Penhill Watermelon with her dinner plate sized blooms is the best I’ve ever seen her. And I grew a new Thomas Edison from a tuber this Spring as well. Aren’t they stunning? I love cutting single stems for little jam jar vase displays in the house.

The Agastache (Giant Hyssop, related to Mint) with her aniseed-scented leaves and tall purple flower spikes is still blooming. As is my lovely Geranium Rozanne, who’s happy in shade, sun, pots, and borders.

I’m also loving my favourite Hydrangea by the front door, who’s perfectly happy in shade for most of the day. On the same colour spectrum are these gorgeous Gladioli Murielae, aka Peacock Orchids. I planted 200 of these corms all around our garden this Spring, and now I want to plant 200 more! Tip: plant in threes or fives, as any designer will tell you, odd number groupings look better than pairs.

Salvias and Verbena Bonariensis are great plants for borders. Hardy, drought tolerant, and repeat flowering if lightly pruned, they’re brilliant for splashes of colour and pollinators love them too. Keep dead heading them to encourage fresh flowers and they should last until the first frosts at least.

Other flowers the bees are loving are some new pink Echinaceas I bought last month (see also this month’s cover picture), and our pretty little Osteospermums which have started flowering again.

We still have some roses putting out their fragrant blooms in the garden this September, including these two pink climbing roses, one by the front door and one by the back door.

And my favourite yellow rose at the front of the house. She starts out a lovely buttery yellow and fades to a luminously pale yellow with pink tinges within a week.

Our two Japanese Anemones are beginning to take over their respective beds, so one of my September gardening jobs will be to divide them both when it’s cooler. This just means splitting the clumps in two with a sharp spade and replanting the one half in its original hole and the other half wherever you have a gap. It stops the congestion and you get new perennial plants for free.

Lighting up some shaded areas are these lovely Asters with their daisy-like flowers. On the left is the mauve Aster Frikartii Monch, the classic Michaelmas daisy, and on the right is Wood Aster with her starry white blooms. Both should keep flowering for at least a couple more months, taking us into November.

Whether our two potted Fuchsias will do the same depends on how soon we have a frost. Last year I didn’t move them into the greenhouse in time, after which all that was left were some dead-looking brown twigs. Fortunately, looks are deceiving, and these tender plants slowly came back to life, albeit half the size they were. Lesson learned for this year though.

On the subject of coming back again, our hardy white Leucanthemum by the pond is now as big as she was before I cut her back, almost to ground level, at the end of July. And our purple Erysimum Bowles Mauve by the back door is also blooming once more. Clearly, both are much happier now the heatwave has passed and we’ve had some rain.

I wouldn’t normally broach the huge topic of Climate Change in a gardening post, but I have to share that two of our Spring flowering plants have flowered again. Our Wisteria should only bloom in May/June, and our Magnolia in April/May. Very strange to see them blooming again in September!

The last of our perennials, and newly planted this year, are our Sedum Purple Emperors, which are late-flowering plants that provide nectar for pollinating insects into Autumn. I’ve not grown Sedums before because I thought they were succulents and not hardy, but you live and learn. And I love the striking purple foliage/pink flower combination, it really stands out in a border.

Wildflowers

I’m a big fan of wildflowers, particularly self-sown wildflowers. Just look at the glorious fernery and the Hypericum thriving underneath the shade of Flora’s trampoline in the orchard. Hypericum, also known as St John’s Wort, is often used for treating various nervous system related disorders. The berries are toxic though, so please don’t eat them, get your supplements from a reputable supplier.

Next to our main wildlife pond the Linaria Vulgaris, or Common Toadflax, is growing again after I cut it back in early August. And our pretty little yellow Welsh poppies are threading their way through all our borders and beds, which makes me very happy.

We also have an interloper in one of our beds – after downloading the Picture This plant i-d app (available on Apple and Google Play), it appears this is Joe Pye Weed. I’ve never seen it before, I suspect it was a rogue seedling hiding with one of our new plants, but its purple umbellifers are very pretty, don’t you think?

Edibles

It’s not only the bees who love our edible garden flowers. The pelargoniums don’t have many flowers left now but we can still harvest their leaves for teas. Tip: September is an excellent time to take cuttings from pelargoniums, salvias, and fuchsias to make new plants (once established, they make lovely presents too). And can you see that fuchsia berry? These are edible too, with a slightly watery cherry-like flavour – they’re ripe once they’ve gone really dark purple.

We have a new pale pink Malva, or Mallow, that’s self-seeded from the parent plant by the pond. And we have a LOT of baby purple Mallows, which have self-seeded from the original plant we had some years ago. I can only think that all the digging up we had to do for our new herbaceous borders back in April kick-started some dormant seeds into life. The flowers on both plants add a splash of colour to salads, although you can only harvest the youngest leaves to eat.

If you’re thinking about growing edible flowers, my top tip is to pick the new flowers, wash them, and use the petals only. The stamens and sepals tend to be bitter. If you’re out foraging, try and avoid any flowers that are blooming at dog level – I’m sure you can guess why… I should also mention that our Cornflowers, Dahlias, Roses, and Sunflowers are edible too 🙂

What to do in the vegetable garden in September

September in the veg plot is extremely quiet, a casualty of my not being around during August this year. My French bean plants were in too much shade, so I’ll cut them away at ground level soon, leaving the roots in situ to release nitrogen back into the soil as they break down. Tip: this works for sweet peas as well. For those of you growing pumpkins, you can help them ripen in time for Hallowe’en by removing any leaves shading the fruits, and sliding a piece of slate or wood underneath them to prevent them rotting on the ground.

Over in the greenhouse, the tomatoes are nearly finished, just a few unripe green ones left. My neighbour also has a lot of unripe tomatoes, so I’m planning on making green tomato chutney with our combined fruits. Then it will be time to clear out the greenhouse, ready for our tender outdoor potted fuchsias to over winter in peace.

In the meantime, if you’re wondering what vegetables to plant outside in September, the good news is the soil is still warm. Think hardy greens and fast-growing salad leaf crops such as kale, pak choi, lambs lettuce, mizuna. And don’t forget your cabbages, Swiss chard, and turnips for Winter meals either.

However, it’s not all doom and gloom, there are plenty of plants to harvest in September, especially on our fruit trees. Apples and pears… Tip: gently lift them and give them a little pull, or twist their stems a couple of times – if they’re ripe, they’ll come away easily.

Followed by figs and plums (although sadly not enough for making plum jam this year)…

And much to my delight, our battered old peach tree fruited this September too – again, not enough to make jam but plenty of sweet and juicy treats to enjoy. She last cropped about 5 years ago, but her fruits are definitely worth the wait!

I managed to harvest all our gooseberries and a handful of blackcurrants at the beginning of August and made some yummy gooseberry jam (with a handful of blackcurrants and a few grapes from the fridge to make up the quantity). Now I need to prune all the bushes back by a third, having already cut back the summer raspberry canes to the base, and tied in new growth to the supports.

Rhubarb season is supposed to be over but our plants clearly didn’t get the memo. I made a kilo of delicious rhubarb and ginger jam in August and it looks like I’ll be able to make some more soon too. But we’ll leave all the grapes on our grapevine for the birds as usual – no need to be greedy 🙂 We’ll just savour the lovely little self-sown wild strawberries all around our garden. Tip: create new strawberry plants for free by pegging down any strawberry runners into pots of compost to set roots – they only take a couple of weeks to get going.

September gardening jobs – things to do in your garden in September

Following this year’s heatwave during July and August, we’ll be installing some new water butts soon, although I’m sure if we do this, next Summer will be a washout, because that’s life. Fortunately, having added a good layer of mulch (I love Strulch*) helped hugely to keep moisture in the soil this year. And it will serve as insulation this Winter too.

Early Autumn is a good time to review your lawn care and fill in any bare patches with turf or seed. Will grass seed grow if you just throw it on the ground? No, it will not, you need to prepare the soil by raking it to a fine tilth, watering it, and then gently press the seeds into it. Tip: wait for a rainy day. And for more established lawns, don’t forget to raise the height of your mower blades as grass growth slows down. Alan is mowing our lawn and orchard grass on alternate weeks now.

For the dedicated lawn carers among you, you can also aerate your lawn by stabbing it with a garden fork, then removing thatch from the surface with a rake. Or you could hire a specialist lawn scarifier if you have a large area to cover. Although I must confess ee don’t bother any more as a lush green sward is very low on our priority list.

Other September gardening jobs to add to your to do list include pruning back lavender plants to new green growth, collecting seeds from your favourite annuals to sow later (I’ll be sowing our sweet peas* in November again), and bringing inside any tender plants, such as Aloe Veras or Geraniums, to over winter indoors now the nights are growing cooler.

Earlier than usual, we’ve started to collect the fallen leaves, which we split between our compost bins and biodegradable leaf sacks* to rot down into leaf mould. This is a brilliant – and free – soil conditioner for your garden plants.  Although we’ll still leave a few leaf piles in corners of the orchard, for the hedgehogs to have somewhere to hibernate safely.

Lastly, one of my favourite September gardening jobs takes place indoors. Choosing my spring flowering bulbs for planting this Autumn, for lots of lovely Spring colour next year. On my list so far are lots of alliums and gladioli…

Gardening for wildlife in September

As always, we’re keeping our bird feeders topped up with quality wild bird food* and high energy fat balls*. And Alan will be cleaning all the hanging feeders and bird tables ahead of Winter, to maintain hygiene for our feathered friends.

We cleared out a LOT of duckweed, pondweed, and algae from all our ponds at the end of July, to give the water lilies and other oxygenating plants room, as well as the frogs, newts, and fish. You’d never know that though, looking at this picture. Time to do it again then, but at least the September rain is keeping them topped up with water, so the birds and other mammals (including our cats) have easy access to drink.

September gardening – a summary

And this concludes my September gardening update, together with your reminders of what to do in the garden now. I swear these gardening posts get longer every time and this one is a record at 2,800+ words – congratulations and thank you if you’re still with me! As mentioned earlier, the soil is still warm at this time of year so if you’re thinking of starting a garden in September, then go for it and let your plants grow away. I can’t believe we’re heading into Autumn already, but this quote about Fall feels is helping me get in the mood:

“Autumn is the season to find contentment at home by paying attention to what we already have.”

Did you enjoy your virtual visit our September garden? How did your outside spaces fare during August? Which has been the most challenging period in your monthly gardening calendar this year?

* This post features affiliate links but all opinions are my own (see my Disclaimer).