Tomatoes Not Ripening? 5 Reasons Why (And How to Fix It)

You’ve watered them, fed them, and watched them grow — but your tomatoes are still sitting there green and stubbornly unripe. Sound familiar? You're not alone! July is peak tomato-growing season, but many gardeners find their fruit isn’t turning red (or yellow, or orange) as expected.

Don’t worry — this is a common problem, and there are simple ways to encourage ripening. Here are the top 5 reasons your tomatoes might not be ripening — and what you can do about it:

1. Too Much Heat

Yes, tomatoes love sun — but if temperatures rise above 29–30°C consistently, they can actually pause ripening. That’s because the plant stops producing the pigment (lycopene) that makes tomatoes red in extreme heat.

Fix:
Provide a little shade during the hottest part of the day using a garden umbrella or shade cloth. Keeping your plants healthy and well-hydrated also helps them cope.

2. Too Much Green Growth, Not Enough Energy for Fruit

If your plants are bushy and leafy but the fruit isn’t colouring up, you may have overfed them with nitrogen (which boosts leafy growth).

Fix:
Switch to a high-potassium feed (like tomato feed) once flowers appear — this encourages the plant to focus on fruit and flower development rather than leaves.

3. Inconsistent Watering

Fluctuating moisture levels can stress your plants and slow down fruit ripening. In some cases, it also leads to problems like split skins or blossom end rot.

Fix:
Water deeply and consistently — especially in containers. Try watering in the morning and adding mulch to the base of the plant to retain moisture.

4. It’s Just Not Time Yet

Different tomato varieties ripen at different speeds. If your tomatoes are large but green, they may be slower-maturing types. Plus, cooler nights in early summer can delay ripening.

Fix:
Be patient — and as the season warms up, you can pinch out the growing tips of your plants to redirect energy into ripening fruit rather than producing more flowers and leaves.

5. Too Much Shade

Tomatoes need plenty of sunlight to ripen properly. If they’re in a shady corner or behind larger plants, that could be the culprit.

Fix:
Move containers into a sunnier spot, or prune back any overhanging plants. You need at least 6–8 hours of sun per day for good ripening.

Bonus Tips to Encourage Ripening:

Remove some lower leaves to let light reach the fruit.

Place bananas near harvested green tomatoes indoors — the ethylene gas helps speed up ripening.

If frost or bad weather is approaching later in the season, harvest mature green fruit and let them ripen indoors.

Need Help?

Pop into Flowerland Bourne End and speak to one of our team! We’ve got tomato feed, plant supports, shade nets, and all the gear to help your tomatoes along. And don’t forget to follow us on Instagram @flowerland.living for more growing tips and seasonal advice.