The crisp, cool mornings that start to appear in the second half of August become regular feature during September, signalling the approach of Autumn. If you sowed seeds for a winter/hungry gap harvest in July and August, you should be assured of a supply of fresh vegetables right through until the Spring. If you didn’t, it’s probably too late for much of a Winter crop, but it’s still OK for the hungry gap. Especially in a polytunnel, where you can really stretch the limits of what you’d grow outside. And, if we get an ‘Indian Summer’, it may stay warm enough for your Winter crop seedlings to get to a good size before the cold weather stops them. Either way, ‘hungry gap’ crops such as sprouting broccoli, early cabbage varieties, coriander and spinach should be ready sometime in April if you sow them now.
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!
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.
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.
Sprouting broccoli, cabbage, cauliflower, coriander, daikon, kohlrabi, lettuce, peas, radish, rocket, spring onions, strawberries.
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.
Please see our Top Of The Crops for a list of over 80 Vegetables, Fruits, Herbs and Spices, Flowers and Exotics.