Vegetables to Sow in September

Many first time polytunnel gardeners make the mistake of thinking that most of the sowing is done in the spring. But when you are aiming for year-round growing and eating, you will sow in the summer and early autumn months as well. September is a time when it can still feel like summer one day, and descends into autumnal conditions the next. Year to year, September weather conditions can vary considerably. But when you have a polytunnel, there are still a number of vegetables to sow in September, whatever the weather. 

Why Sow Vegetables in September?

The vegetables you sow in September will not feed you over the winter months. Rather, they are generally sown now in order to overwinter in your polytunnel and feed you during the spring ‘hungry gap’ next year. September in the polytunnel, therefore, is generally about thinking ahead. It is about taking advantage of the last of the growing season to create young plants that can successfully overwinter before bursting back into full growth next year when the warmer weather arrives.

The benefit of sowing vegetables this month and next is that overwintered vegetables can produce their harvest up to a few weeks earlier than vegetables sown early in the spring. Another benefit of sowing vegetables now is that they can fill gaps in your growing areas that are vacated by summer crops, and so make sure that the soil in your polytunnel is covered and protected over the winter months. This can help to keep the soil ecosystem in your polytunnel healthy and thriving all year round. It will help ensure that your soil can grow plants, and feel you and your family, for years to come.

Choosing Vegetables to Sow in September

The vegetables that you can sow in September in your polytunnel will, of course, depend on where exactly you live and the conditions that can be expected there over the coming months.

It will also obviously depend on whether or not you heat the polytunnel structure and how cold it is expected to get. You can extend the number of vegetables that you can sow this late in the year in colder regions by providing crops with a little extra protection – for example, in the form of a mini polytunnel or cloches, a hot bed, or additional thermal mass within the structure.

When choosing vegetables to sow in September, it is important to consider your own specific polytunnel, and the conditions where you live. In addition to considering the air temperatures, it is also a good idea to take soil type into account – heavy clay soils, for example, are far colder and more prone to waterlogging in winter and may restrict the options for winter growing, even with a polytunnel.

You will also have to consider the seeds that you choose carefully. While there are a range of different vegetables that can be sown in early autumn, it is vital to choose seeds that are suitable for overwintering, and varieties of each type of vegetable that are meant for autumn sowing.

Vegetables to Sow in September

To help you to make your plant selections, here are a number of vegetables to sow in September:

Peas for Overwintering

If you have collected your own peas and beans to sow, then early autumn is a good time to check these over and ascertain whether they are viable. It can be a good idea to soak seeds to check that they sprout before planting, as this can often mean a higher success rate for autumn sown seeds. If you have not collected your own seeds to sow then you should buy these now, in early autumn. Try to buy from a reputable company, either online or in your local area. You may wish to consider choosing organic seeds, and heritage varieties, to do your bit for the planet.

One general rule to remember when selecting peas for overwintering is that peas which are round and smooth will be better for autumn planting, while those which are wrinkly are best sown in the spring. Some good varieties to plant in autumn are:

• ‘Amelioree d’Auvergne’
• ‘Douce Provence’
• & ‘Meteor’

Try ‘Glory of Devon’ as a dwarf variety, or Serpette Guilloteau if you prefer a climbing pea.

Broad Beans for Overwintering

Broad beans also have varieties that are best planted in either autumn or spring. It is important to make sure that you choose a variety that is suitable for overwintering where you live. Broad bean varieties often sown in autumn in the UK include:

• ‘Aquadulce Claudia’
• Superaquadulce’
• & ‘Witkiem Manita’

A polytunnel can make it easier to overwinter broad beans, even in colder regions of the UK. But where winter conditions are more extreme, you can also consider choosing field beans instead. These are hardier than regular broad beans and will overwinter successfully wherever you live in the UK.

Brassicas

There are still also several brassica plants that can sown at this time of the year. Mustard, for example, can make a useful cover crop or green manure over the winter months, or used for leafy salads. 

You can also still consider sowing kale now. There will, of course, not be time for a mature harvest before winter, but sowing some now will give you a harvest of greens early next spring, or you could use kale and other brassicas to provide you with micro-greens over the winter months.

You could also consider sowing some broccoli raab, or rapini, for a harvest just 40 days later. This plant is related to turnips, but grown in the same way as broccoli, and produces sprouts that taste like a slightly spicy sprouting broccoli.

Asian Greens

There are also a range of Asian salad crops or greens that you can keep sowing in your polytunnel at this time of the year. Mizuna and Komatsuna are the hardiest mild-tasting greens, though with a polytunnel you can also continue sowing pak choi, mibuna, Chinese cabbage and a range of other vegetables, even this late in the season. 

Winter Lettuces

Lettuces can also often be sown right through until near the end of the year when you have a polytunnel, especially if you also offer some extra protection. Winter marvel and Reine de Glace are two varieties that can be sown right through into November. As long as you choose the right varieties for each time of the year, there are lettuces to grow all year round in your polytunnel. 

Rocket

Rocket is another hardy leafy crop that you can sow in September, and which will survive perfectly well in your polytunnel all winter long. It can be used to add a little peppery taste to salads, but can also be cooked in a wide range of recipes. 

Radishes

Your salads over the winter months can also be enlivened by the addition of some radishes. Radishes are quick to grow and there is still the chance to grow some before the end of the growing season. In a polytunnel, you also have additional protection, which allows you to extend the season and also to grow other types of radishes over the winter months. Daikon radishes, and black Spanish radishes are both options that you could consider. 

Spring Onions

Another crop that you can consider sowing and growing in your polytunnel pretty much all year round is spring onions. Sow some spring onions now for a very early harvest in the spring. There are a range of different spring onions and bunching onion varieties that you could consider. 

Speaking of onions, towards the end of this month you could also consider planting some onion sets. Just be sure to select a good overwintering variety. Next month, you can also sow some garlic in the protection of your polytunnel, or outside in your garden.

As you can see from the above, there are more vegetables to sow in September than you may have imagined. Getting on with sowing even in early autumn is an important part of growing all year round. This is so much easier and more effective when you are lucky enough to have a polytunnel. What have you sown this month? Let us know in the comments below.