Why Are My Tomatoes Not Ripening?
Green tomatoes can be perfectly healthy, yet stubbornly slow to colour. In British gardens this is often a late-season temperature and light issue, although overfeeding, dense foliage or a variety's naturally long season can contribute. A few timely changes can help you make the most of the crop before autumn weather closes in.
Start by checking how far the season has progressed and where the plants are growing. Tomatoes need sustained warmth to colour well, so fruit often stalls during cool, dull spells from late August onwards, particularly in northern gardens and Scotland. A greenhouse or polytunnel usually gives more reliable ripening than an exposed border. Check that the variety suits your space too: large beefsteak types need longer than cherry tomatoes. Remove any fruit that is damaged, split or clearly diseased, then focus the plant's energy on sound tomatoes. If nights have become cold, close greenhouse doors early in the evening and use horticultural fleece temporarily where ventilation still allows.
Reduce excessive leafy growth, which can shade fruit and divert the plant's energy. Stop applying fertiliser once a good crop has formed, especially feeds that encourage fresh green growth. With clean secateurs, remove a few leaves that directly block light and airflow around each truss, working gradually rather than stripping the plant bare. Take out yellowing, soil-splashed or crowded lower leaves first. Keep the remaining foliage because it still feeds the plant and protects fruit from sudden strong sun. For cordon tomatoes, pinch out the growing tip above the highest developing truss you expect to ripen. This is particularly useful from August in cooler areas, or during September in milder southern gardens.
Keep watering consistent while fruit is ripening. Letting compost become very dry and then soaking it can cause splitting and stress, neither of which helps colour develop. Water at the soil surface in the morning, avoiding wet leaves where possible, and make sure pots have free drainage. Tomatoes in containers may need watering daily during warm weather, but check compost first rather than following a fixed routine. Mulch border plants with garden compost to steady moisture levels. In a greenhouse, ventilate on warm days to prevent overheating, but avoid leaving plants exposed to chilly draughts at night. A nearby water butt can make regular watering easier during dry spells.
Assess the fruit itself before waiting longer. A tomato that has reached full size and is starting to soften or show a pale yellow, orange or pink flush will usually finish colouring. Very dark-green, hard fruit may simply need more warmth or may not have matured enough before conditions changed. Lift a leaf and check whether fruit is hidden inside a dense canopy. Do not rely on direct blazing sun alone: warmth and an active, healthy plant matter more. If a truss is heavily laden, pick the ripest fruit first to reduce weight and improve air movement. Continue checking every few days, as tomatoes can change quickly in a warm spell.
When autumn weather turns reliably cool, harvest mature green tomatoes rather than risking them outdoors. Choose fruit that is full-sized, unblemished and beginning to lose its deep green colour. Bring it indoors and place it in a single layer in a dry room at ordinary room temperature, away from cold windowsills and direct sun. Check it regularly and remove any fruit that begins to spoil. Keeping a ripe banana nearby can speed ripening, but separate fruit if you want a slower, more even result. Do not refrigerate green tomatoes, as cold can permanently reduce their ability to ripen. Use any fruit that remains hard and green for cooking rather than expecting every one to turn red.
Plan ahead for next season if this happens regularly. Choose early or cherry varieties for an exposed plot, start seeds in module trays at the appropriate time, and plant out only after the last spring frost has passed and nights are mild. Give each plant adequate spacing, sturdy support and a sunny position sheltered from prevailing wind. Improve heavy soil with well-rotted manure or garden compost, but avoid making it overly rich. In containers, use fresh peat-free multipurpose compost and a pot large enough to hold steady moisture. A greenhouse, cloche or polytunnel can add valuable warmth in cooler regions. Keep notes on varieties that ripen reliably in your own garden or allotment.
Frequently asked questions
Can I pick green tomatoes and ripen them indoors?
Yes, provided they are full-sized and have reached the mature-green stage, often shown by a lighter, less intense green colour. Keep them dry in a single layer at room temperature, checking often. Fruit picked very small, hard and dark green is less likely to develop good flavour or colour.
Should I remove all the leaves from tomato plants?
No. Removing all foliage weakens the plant and can expose fruit to sun scorch. Instead, remove only yellow, damaged, congested or fruit-shading leaves a little at a time. This improves light and airflow while leaving enough healthy leaf area to support the remaining crop.
Why do greenhouse tomatoes stay green in a hot summer?
Extreme heat can also slow colour development, especially if the greenhouse is poorly ventilated. Open vents and doors during the day, provide shade in fierce sunshine, and keep watering even. Once temperatures settle, healthy mature fruit often resumes ripening, provided plants have not become dry or stressed.
General guidance for UK home gardens and allotments. Conditions vary by region, soil and season; the RHS or a local garden centre can give site-specific advice. Page updated 19 Sep 2026.