Sowing seeds in August

Sowing seeds in August – perhaps not the most obvious of gardening tasks to many, but an easy one and one that will bear fruit – and flowers and vegetables!

There are three main reasons why summer seed sowing is a good idea –

Firstly you can take advantage of the free flower seeds that your garden plants are producing. This means you can for extend the flowering season for next year at no cost to yourself – very economical.
Secondly you can plant green manures to protect and improve your soil over the winter.
Thirdly you can sow vegetable seeds and salads to provide you with an edible crop during the autumn and winter. Growing vegetables to provide year round food, even if it’s just a few choice vegetables is very satisfying.

What seeds could be sown this month?

One thing to remember is that nature’s calendar isn’t on her desktop, tablet or phone, so she’s less bothered about it being August as such. Instead nature considers the weather (ie hot, cold, wet, dry) and how long the daylight hours are. For example, if you’re told on the packet that a flower seed should be sown in September or July, it is probably okay to sow it in August. And if you’re not sure please ask me the question via social media or email (links at the end). I won’t think you’re daft!

Sowing seeds in August – flowers

Sowing seeds in late summer is a good idea as for many plants, as it is the natural time for them to have set seed and be ready to disperse them to a suitable place where the seeds can then germinate. And you can let the flowers do just that – self sow.

However, some flowers simply let loose their seeds to cover as wide an area as possible in the hope of finding a good growing place. Which means the issue with this laissez faire approach you may end up with seedlings in places where you didn’t want them! But many seedlings can be lifted and transplanted when small. Although some, such as annual poppies, don’t like their roots being disturbed. If these are in the wrong place you usually have to compost the seedling.

Annual flowers you could allow to self-sow in your garden include –

Botanical Latin	Common Name
Borago officinalis	Borage
Calendula officinalis	Marigold
Centaurea cyanus	Cornflower
Cerinthe major purpurascens	Honeywort
Cosmos bipinnatus	Cosmos
Lathyrus oderata	Sweet pea
Nigella species	Love-in-a-mist
Papaver rhoeas	Field poppy, Shirley poppy
Papaver somniferum	Opium poppy
Tropaeleum majus	Nasturtium

Self-sowing plus

This is a term I use to describe how I let some annuals self-seed but also collect seed from them. I do this with biennials such as Lunaria, Honesty, as well. These seeds I sow where I would like them to flower next year. An exception would be the Sweet peas as although I invariably find some self-sown seedlings, I generally collect the seed and sow in a cold frame.

Collecting seeds from your garden is covered in another blog – the link is at the end.

In fact any flower or plant described as a ‘self-seeder’ can be left to do its own thing. It helps to make your garden easy maintenance. Which means you can relax in the garden with the kids or a cup of tea.

Why is sowing seeds in August good gardening practice?

The soil should be warm from the sun’s rays over spring and summer. And, with a moist soil, these seeds will immediately start the germination process. This is true of both self-sown seeds and those you’ve sown yourself.

Buying seed packets is a wonderful August pastime. Garden centres and on-line seed companies often have sales of seed packets which are getting near their sell by / sow by date so there are plenty of bargains to be had!

Once sown or dispersed, seedlings appear quite quickly and are small plants by late autumn. They’ll go into semi dormancy over winter. Most will survive hard frosts without any extra care from you, to romp away in the spring. A further bonus is that they’ll flower earlier than their spring sown relations.

Sowing seeds in August – vegetables and salads

Why else might we want to sow seeds now rather than the spring? Lunch and dinner would be good reasons. Many salad crops still have time to germinate and produce a crop before the autumn. For example:

Annual spinach
Coriander
Lettuce – cut & come again varieties such as oak leaf
Mizuna
Pak choi
Salad rocket

And making later sowings of these as well will give you early salads in the spring. The easiest way to accomplish this is to either let some of your August sowings self-seed. But that can be unacceptably random for many gardeners. Instead why not let 1 or 2 plants set seed, collect the ripe seed and sow some of it straight away where you want them to grow.

Garden Teacher Tip

Most hybrid F1 varieties are sterile or will produce a mix of shapes and types which are not generally suitable and / or crop poorly. If collecting your own veg seed is important, look for ‘open pollinated’ or ‘real’ seeds when first buying them.

Other vegetables can be sown now to provide winter salads and ‘greens’ for soups and stews. Cabbage and Kale, obviously, but why not try Swiss chard, which will also look decorative if you plant the variety ‘Rainbow Lights’ which has yellow, red and orange stems as well as green. These crops will stand outside whatever the weather, but other crops can be sown now and grown under cover.

There are other vegetable seeds that can be sown. For example, you may prefer to grow your onions from seed rather than sets (which are actually small bulbs). These should be sown now through to October. Garlic bulbs and seeds can also be planted.

And if leafy vegetables are a favourite, there are many to choose from, including Lettuce ‘All Year Round’ (which speaks for itself!) and the evocatively named Mustard leaves ‘Green in Snow’.

Sowing seeds in August – green manures

There are also green manures to protect and improve your soil. These work in various ways, for example by covering soil that would otherwise be exposed to the winter weather. Planting a leguminous green manure, such as Crimson Clover, both covers the soil and ‘fixes’ nitrogen into the soil. It’s a good green manure to sow in an area destined for brassicas – cabbage, broccoli – the following spring. For more on green manures, see the blog link below.

and finally…

Final point – whilst most of these seeds sown in August will produce small plants that should be hardy, you may need to give frost protection to some of them, some of the time. For example, a sudden hard frost or a prolonged frost. You could hedge your bets and sow some outside in the ground and a few in a cold frame or small polytunnel.

Nevertheless, it is almost always worth sowing at least a few seeds in August. If nothing else, the thought of picking lettuce from your garden for a Boxing Day salad has a certain satisfying ring to it!

How else can we inspire you?

So there you have it, a few ideas and options if you would like to try sowing seeds in August. If you need some tips on ‘how to’ sow seeds in the garden have a look at our ‘How to’ video on seed sowing and check out the blogs below.

If you would like help with propagation techniques, you may prefer hands-on personal help from yours truly, with a mix of practical sessions and theory in our bespoke Gardening Lessons and Courses There’s a pdf download with more info: Plews Gardening Lessons Information

And for further gardening advice and inspiration, check out Plews Potting Shed blogs and Free Printables , including the selection below and our monthly Tipsheet You could come and find us on Instagram Pinterest and Facebook too.

And on that note, you can have a peek at the progress of my garden renovation, Spitfires and Slow Worms, on Instagram and Facebook You may even get to see it in person later this year / early 2025 as I’m planning a couple of workshops. I had hoped to do that already but house renovations have been as big a thing as garden reno so there hasn’t been the room. Keep an eye on the website and social media for an update.