What to sow and grow in August

Sowing seeds in August

Some people refer to August as a ‘second spring’ because of its potential as a pivotal growing month, but thinking in terms of spring can catch you out.

In spring each week you delay matters little, because light levels and heat are increasing, so if you delay sowing, your delayed seedlings rapidly catch up with your earlier ones and sometimes grow better in the end.

When growing in August, and to an even greater extent in September and October, weeks really matter. Each week you delay deprives a seedling of optimal growing conditions. Start too early though and you end up having to clear beds to make space for new plantings that you don’t need and that won’t thank you for planting them out when it’s still a little warm for them. Often early plantings will mature too early giving you a glut in autumn and nothing to eat in winter.

So the bottom line is that ‘timings matter’ at this time of year, in a way that’s just not true in spring. You can imagine this as every week you delay in early August delays harvest by two weeks in Autumn, in early September a one week delay might delay harvests by a month, in late September a week’s delay might mean no harvests in winter and having to wait until spring.

How much light you can give your seedlings is important too. I generally start my seedlings at home and I don’t have good light there, so I often use grow lights, to allow me to plant at 3-4 weeks from sowing. Without lights, seedlings might take 5 weeks to be ready for planting and be weak and leggy, the 1-2 week delay to planting time in September or October makes a big difference!

Since light and heat are in such short supply in late Autumn and Winter and winds are strong you also need to consider anything else that will affect sowing dates:

• Your microclimate

• Whether your plants will grow in full sun or light shade

• How much protection you can provide from the wind, coping with windy conditions uses up a lot of energy, that’s diverted from leaf/root growth and often makes leaves tough

• Whether you can increase warmth with polythene, glass or fleece (I don’t like fleece myself, but it’s better than nothing sometimes)

• How to keep plants warm but ventilation high to stop fungal issues

• Whether you can provide supplemental light (using grow lights) for late September/October sowings, sowing later gives summer plantings more time to finish harvesting

All of these factors will shift my recommended sowing dates around. In my sowing guides I try and offer up some suggestions to help, but bear in mind these are my dates and yours might vary, you need to think for yourself, my dates, or anyone else’s date’s will rarely be ‘ideal’ for you. I will have another article next week about the concept of ideal sowing dates!

If you have a windy plot then this video might be useful as we are currently really suffering from high winds here in Lytham St Annes.

Here’s a screenshot from my growing guide for September, lots of information!

Let’s drill into Tatsoi

For this succession (for harvesting over winter) I’m sowing in mid-September (probably on or around the 13th) and I’m pricking out about 6-10 days after sowing into a 40 cell tray.

I’m germinating my seeds on a little shelf unit that I have in a cool bedroom, which provides a nice stable temperature of 15-18c, seedlings seem to love the stability. Once germinated seedlings move to a sunny windowsill for about a week.

After pricking out I will move the seedlings under grow lights, but only for 10 days and only because I have no bright place to grow them at home. After 10 days I will move the seedlings to my polytunnel for another week, before planting.

Although they don’t need much protection in October, by November they will, so I’m planting the Tatsoi in my polytunnel, where the extra heat will double/triple their growth rate compared to plants grown outside, allowing me to harvest through winter.

My gardening database has successions data for everything that I grow, which includes suggested sowing, planting and harvest dates, but also suggested pot sizes and details of how to protect plants from pests or weather as needed.

Here’s an screenshot for Asian greens:

What I’m sowing in August

There’s a huge variety of things that you could potentially sow in August and my successions table provides some guidance. You can browse the successions for August online. It looks like this:

If you want to plan ahead, then you can find my successions for September here too.

I’m not sowing everything on this list and I’m also sowing a few things that aren’t on this list because I’m always experimenting.

You can find the list of everything I’m currently planning to sow in my August sowing plan. Here’s an extract, which you can’t read, but notice the blue bars (which don’t show up on the phone app) , these highlight experimental sowings, everything without a blue bar is tried and tested.

In most cases everything in this list is self explanatory, but here are some extra notes on a few of the entries:

• August is a good time to restart sowing radish and turnips, they taste so much better than ones grown in summer. But don’t delay too long. It takes a lot of energy for plants to grow roots and they run out of energy for me in late September. Do most of your sowing in August, but take comfort that the roots stay in good eating condition for a few weeks in the cooler weather of late September and October

• Salad onions for eating in Autumn are best sown in July, but early August is still an option, as you progress through August the likelihood of getting good sized onions this year decreases and by the end of August you will be harvesting in spring. Also don’t be tempted to plant your salad onions under cover too early, as it’s too hot for them, they will grow weak and floppy.

• Lambs lettuce is a very important salad ingredient for winter, it grows outside and matures just as true lettuce stops growing in mid-December. However sow it too early and it often develops mildew unless you keep it very well watered. Sow it too late though and it won’t mature until spring. It’s also fairly sensitive to light levels, so early August is good for a winter harvest in light shade, if you have full sun you can sow it a little later. Don’t be tempted to grow it under plastic or glass

• Miners lettuce or Claytonia is even better over winter, and it will grow outside too. However unlike lambs lettuce it really thrives under cover and the leaf size and quality is much improved. So much so that most of my Claytonia will be planted under cover this year.

• It’s now too late to sow kale for a harvest this year, unless you grow it under plastic and even then the main harvest period will be in spring. I usually wait until August to make a decision, if my existing brassicas are growing well I won’t bother sowing it, but if I have a lot of losses, maybe cabbage root fly for example, then I might sow a few.

• Japanese over-wintering onions - I grow Toughball - can be tricky in our unpredictable winters. Sow them too early and in a mild winter they will be too big in spring. They will conclude they are in their second year and go to seed. Sow them too late and they will be too weak to make it through a harsh winter. No one knows whether we will have a mild or harsh winter, so I sow a few successions, through August, then come late spring or early summer I will know which to harvest early and which to leave to mature.

• Lettuce really thrives from an August sowing and can struggle on outside into Winter, but growth rates slow down dramatically. I tend to remove my August sowings in late Autumn and replant with spinach for a harvest in spring or maybe garlic or field beans. By then the lettuce that I sowed in September and planted under plastic in October is ready for harvest and this will be harvested through late autumn, winter and early spring

• Spinach does well from an August sowing and will do well until winter, when growth really slows down. It will restart growing in early spring. However it does so well that you can easily get a glut in September and early October. I sow only a moderate amount in August and sow most of mine through September, to be planted under cover in October. Under plastic in a cold frame spinach keeps growing all through winter.

• Just like lettuce, Asian greens grow well outside from an August sowing, but they benefit from a mesh cover as the wind picks up. Just like lettuce though growth stalls in winter and unlike lettuce they often go to seed in winter or very early spring. I find it best to sow another batch in mid September to grow in the polytunnel for a harvest in winter.

• I’m repeating myself now! Salad rocket also does well outside until late Autumn and then it too stalls and leaf quality declines a lot. So a September sowing to grow under cover might be worthwhile. For me though it’s not really worth it, as I prefer to grow more Claytonia instead. I interplant my Autumn salad rocket with garlic and then when I remove the rocket in December, the garlic grows on undisturbed.

Growing guides

I have over fifty comprehensive growing guides, that include lots of extra videos, for every veggie that I grow, you can find the guides relevant to August sowings in the growing month by month, section of my ebook.

Previous years

I think evidence of success is very important. So I recommend you take a look at my actual results from these suggested sowings. All too often pundits - like me - will say sow x in August, but never follow up with their results, I wonder why?

You can look back at what I actually sowed, planted and harvested in previous years in August in the reference section of my eBook. This also has links to all of the videos from August as well as garden tours and much more. Here’s the links for August 2022 and August 2023.

You can look at any other month too.

Harvests

Of course sowing is important, but what’s really important are harvests. Here are some of my harvests in August from previous years:

Interested in the app I for all of this?

You can find all the details in the chapter of my eBook that covers my database/app, it has lots more videos. Or you can just get started with this video: