September is a month of transition. Summer growth is slowing, but there is still plenty to harvest while attention begins to turn towards autumn and preparing the plot for the cooler months ahead. Keep picking productive crops, clear ground as it becomes available and make a few late sowings to extend the season.
Harvesting & Storing
Beans, courgettes, cucumbers and tomatoes can still be producing well. Pick little and often to keep plants productive and avoid gluts going to waste.
Maincrop potatoes can be lifted once the foliage has died back. Choose a dry day if possible and allow the potatoes to dry before storing them somewhere cool, dark and frost-free. Check them first and use any damaged tubers rather than putting them into storage.
Onions and garlic should also be lifted once ready and dried thoroughly before storing in a cool, airy place.
Pumpkins and winter squashes will be approaching maturity. Once harvested, leave them somewhere warm and dry to cure so that their skins harden before storing them for winter. Leave a short length of stalk attached, as this helps them to keep.
Sow & Plant
There is still time to sow hardy leaves such as spinach, rocket and some Oriental greens for autumn cropping. Radishes and fast-growing salad leaves can also provide a final crop before winter.
Spring cabbage can be planted out this month, and autumn-planting onion and shallot sets can begin to go in towards the end of September.
Garlic planting can wait until October and hardy broad beans until October or November, so there is no need to rush these into the ground.
Cover autumn salads and Oriental leaves with fleece or cloches as the weather cools to extend their cropping season.
Fruit
Once summer-fruiting raspberries have finished, cut the old canes that produced this year’s fruit down to ground level. Leave the new green canes, which will carry next year’s crop, and tie them into their supports.
Stone fruit such as plums and cherries can be pruned after harvesting while they are still in active growth. Avoid leaving this until winter, when pruning increases the risk of silver leaf disease and bacterial canker.
Keep harvesting autumn raspberries and other soft fruit as it ripens — preferably before the birds discover it.
Looking After the Soil
As crops finish, clear away spent plants and weeds rather than leaving beds until spring.
Healthy plant material can go onto the compost heap. Diseased material and troublesome perennial weeds should be kept out and disposed of appropriately.
Bare beds can be given a layer of compost or well-rotted manure, allowing worms and winter weather to gradually incorporate the organic matter into the soil.
Alternatively, sow a suitable green manure on ground that won’t be needed for some time. This will protect the soil surface, suppress weeds and add organic matter when it is eventually cut down.
Tidying Up
Don’t be too quick to dismantle everything simply because September has arrived. Beans and tomatoes may continue cropping well into the month if the weather remains warm.
As individual crops finish, however, supports and canes can be taken down, cleaned and stored for next year.
Remove dying leaves from crops and keep weeds under control. Apart from making the plot look better, removing unhealthy plant material can reduce places for pests and diseases to overwinter.
Saving Seed
Beans and peas from open-pollinated varieties can be allowed to mature fully on the plant and dried for seed to sow next year.
Tomato seed can also be saved, although remember that seed collected from F1 hybrid varieties won’t necessarily produce plants like their parents.
Label saved seed with the variety and year. It is remarkably easy to convince yourself that you’ll remember what it is six months later!
Think Ahead
September is a good time to look back over the growing season. Make a note of varieties that performed particularly well — or particularly badly — while you can still remember them.
Prepare cloches, fleece and netting for autumn and winter crops, and think about which beds will be needed first next spring before deciding where to put green manure or overwintering crops.
September can still feel like summer on a warm day, but the shortening days are a reminder that autumn is on its way. Make the most of the remaining harvest while getting the plot ready for the season ahead.