September Growing Guides

September is a turning point. Keep harvesting summer crops while making timely space for plants that will grow through autumn and the hungry gap.

SEPTEMBER IN THE POLYTUNNEL: AT A GLANCE

SEPTEMBER IN THE POLYTUNNEL

September is also decision time for polytunnel gardeners: do you leave that ‘summer’ plant in place in hope of a continuing harvest, or do you take it out and replace it with some of your winter crop seedlings? I always face a dilemma over this, but sometimes my decision is made for me – such as when I accidentally stepped on the courgette I was hoping to nurture into November! However, it’s not a time to dither: two weeks of growth at this time of year can make a huge difference later on, and you miss it at your peril.

If you’re planning on overwintering peas and broad beans, September (or even early October) is the ideal time to sow them. They should then be big enough to stand through the cold weather (unless it’s really cold, in which case they’ll need protection) and will grow on in February and March to provide a welcome harvest starting sometime in April.

Climbers such as cucumbers and melons should have been grown near the cover on the north side of the polytunnel so they don’t take up valuable bed space or cast too much shade. Leave them in place for now, as cucumbers can bear fruit well into November (possibly even December) and melons will ripen between mid-August and the end of this month. Cucumbers should not be stored in the fridge or they will go soft after just a few days. Instead, wrap them in cling film and put them somewhere dark and cool. So long as they don’t freeze they will keep for several weeks – you might even end up putting them in a salad over the Christmas holidays!

Local conditions matter: These are possible crops, not guaranteed harvests. Timing depends on the crop variety, earlier sowing dates, light, temperature and whether your tunnel is heated.

WHAT TO SOW IN SEPTEMBER

Sprouting broccoli, cabbage, cauliflower, coriander, daikon, kohlrabi, lettuce, peas, radish, rocket, spring onions, strawberries.

WHAT TO HARVEST IN SEPTEMBER

Aubergine, cabbage, carrot, cauliflower, celeriac, celery, chard, coriander, courgette, cucumber, daikon, dwarf French and French beans, fennel, kohlrabi, lettuce, melon and watermelon, pak choi, pepper, radish, rocket, spinach, spring onions, strawberries, sweet potatoes, tomato.

ESSENTIAL POLYTUNNEL JOBS FOR SEPTEMBER

Tip 1

If you had an onion crop in an outside bed, or in the polytunnel, your polytunnel is an ideal place to dry them for storage. As it’s much warmer near the ridge of the polytunnel a suspended shelf or net hung several feet off the ground makes a great drying rack. Turn the onions every couple of days to ensure they dry evenly, and don’t pack them away for storage until their necks are completely dry. To check, grip the neck just above the bulb and roll it between your fingers. If it feels at all soft, there’s still moisture inside and it should need to dry further. Incidentally, bending down the necks of ripening onions while they’re still in the ground can sometimes lead to trapped moisture that will be very slow to dry. To learn how to braid your own onion and garlic strings, see ‘How To Grow Food In Your Polytunnel’ book.

Tip 2

If you have an automatic watering system in place, September will see a marked decrease in the amount of water your plants need: check to make sure they’re not getting too much.

Find individual crop advice in our Top of the Crops guide, or browse all monthly growing guides.