September is a transitional month for tomato growers in the UK. The days are getting shorter, nights cooler, and the growing season begins to wind down. While summer’s warmth has helped ripen many fruits, there are still plenty of ways to keep plants productive and get the most from your crop. Here are three key things to focus on this month:
- Encourage Ripening of Remaining Fruit
By September, most tomato plants are loaded with green fruit. To help these ripen before the season ends:
- Pinch out any new flowers – the plant no longer has time to develop them into mature tomatoes.
- Remove some of the lower leaves to let sunlight reach the fruit and improve airflow.
- If frost is forecast, harvest green tomatoes and ripen them indoors on a sunny windowsill or in a paper bag with a banana.
- Keep an Eye on Watering and Feeding
Tomatoes still need care in September, even if growth slows:
- Water consistently but slightly less often than in high summer; cooler days mean soil doesn’t dry as quickly.
- Switch to a high-potash feed (like tomato fertiliser) every week or so to support the final flush of fruit.
- Avoid overwatering, which can lead to split skins and dilute flavour at this stage.
- Protect Against Early Autumn Conditions
September weather in the UK can be unpredictable, with damp spells encouraging disease:
- Remove yellowing leaves promptly to reduce the risk of blight.
- If plants are outdoors, consider a cloche or fleece to shield them from rain and cold nights.
- Greenhouse growers should keep vents open on warmer days but close them earlier in the evenings to trap heat.
With just a little extra attention in September, you can make the most of the final weeks of the tomato season in the UK, enjoying ripe, flavour-packed fruit well into early autumn.
