September is here, and if you've been growing tomatoes outdoors this year, you're in the final straight. The nights are drawing in, temperatures are dropping, and your plants are starting to tell you the season is winding down. But there's still plenty you can do to get the most from your crop before the cold sets in.
Here's your Go Grow guide to finishing off your outdoor tomatoes properly.
Know When to Stop Feeding
Once your plants are loaded with fruit and new flowers have stopped setting, it's time to stop applying liquid nutrients. Continuing to feed at this stage pushes the plant to keep growing when you want it to focus its energy on ripening the fruit that's already there. Switch to plain, pH-balanced water for the final few weeks.
Remove the Growing Tips
Pinch out the very top of each plant — this is called "stopping" the plant. By removing the growing tip, you redirect all remaining energy away from new growth and into ripening your existing fruit. Do this now if you haven't already.
Strip the Lower Leaves
Remove any yellowing or dying leaves from the bottom third of the plant. This improves airflow, reduces the risk of fungal disease in the damp autumn air, and helps sunlight reach the lower fruit clusters. Don't strip healthy green leaves higher up — the plant still needs those to photosynthesise and ripen fruit.
Bring the Heat to the Fruit
Tomatoes ripen in response to warmth, not sunlight. On cooler days, you can help them along by laying a reflective sheet or white plastic mulch beneath the plants to bounce warmth up from the ground. If you have a cloche or fleece, use it at night to hold warmth in as temperatures dip.
What to Do With Green Tomatoes
If the first frost is forecast and you still have a lot of green fruit on the vine, don't panic. You have a few options:
- Leave them on the vine a little longer — tomatoes will continue to ripen slowly in cool conditions, right up until frost
- Bring them indoors — place green tomatoes in a single layer in a warm room (not the fridge). They'll ripen gradually over the next few weeks. Adding a ripe banana nearby speeds this up — the ethylene gas helps trigger ripening
- Make green tomato recipes — green tomato chutney is a classic, and a great way to use up a glut before they spoil
Deal with Blight Early
September's damp, cool conditions are prime time for late blight — the brown patches and white mould that can sweep through a crop fast. Check plants daily. If you spot it, remove and bin (don't compost) affected material immediately. Once blight takes hold, it moves quickly, so act fast.
Clear and Compost at the End
Once your plants are done, remove them completely. Tomato plants left to rot in situ can harbour disease and pests that overwinter in the soil. Healthy plant material can go in the compost; anything showing signs of disease should go in the bin. Then dig in some compost or a soil amendment to restore what the season took out of your beds.
Think About Next Year
Avoid planting tomatoes (or any other Solanaceous crops — peppers, aubergines, potatoes) in the same spot next year. Rotating your beds reduces the build-up of soil-borne disease and gives your soil structure a rest. Now is also a good time to note what worked, what didn't, and which varieties you'd grow again.
Ready to set yourself up for a better grow next season? Browse our full range of soil amendments, nutrients, and propagation kit — so you're ready to hit the ground running when spring comes around.