Why Are My Tomato Flowers Not Setting Fruit?
Tomato flowers need suitable temperatures, steady moisture and some movement of pollen to set fruit. Cold nights, hot humid days and dry roots can all leave flowers without developing tomatoes. Check growing conditions first, especially under glass, then make small adjustments while new flower trusses continue to open.
Start by observing what happens after flowers open. If blossoms dry up and fall without a tiny tomato forming behind them, poor pollination or temperature stress is likely. Look for healthy foliage, firm stems and a moist but not saturated root zone. A few early flowers may fail during unsettled weather, especially on newly planted tomatoes, and this is not always a serious problem. Keep notes on whether failure occurs outdoors, in a greenhouse or only on certain trusses. Different varieties respond differently, and cherry tomatoes can set more readily than some larger-fruited types. Do not remove every failed truss immediately; new flowers may follow as conditions improve.
Protect tomatoes from cold nights and sudden temperature changes. Plants generally set poorly when nights are chilly, so avoid planting outdoors before the likely last spring frost and harden young plants off gradually. In a greenhouse or polytunnel, close doors before a cold evening and use fleece over plants if a late cold snap is expected, removing it in the morning. In Scotland, northern gardens and exposed sites, growing tomatoes under cover is often more reliable. Avoid placing pots directly on cold ground where practical. Once weather settles, give plants plenty of light and avoid excessive insulation on sunny days, because trapped heat can create the opposite problem.
Ventilate glasshouses during warm, humid weather. Excessive heat and stagnant humidity can make pollen sticky or less viable, so open doors, vents and louvres whenever conditions allow. Provide shade only during exceptional, intense heat, and ensure it does not reduce light all day. Space plants so air can move between leaves, train cordon tomatoes to supports and remove foliage only as recommended for your type. Water in the morning, aiming at the compost or soil rather than flowers and leaves. A clean, airy greenhouse also makes it easier to notice pests and mould early. Outdoor plants benefit from a sunny but sheltered position, not a completely enclosed corner.
Help pollination under cover by gently tapping or shaking cordon plants around midday on dry, mild days. The vibration releases pollen within each flower, and repeating this as flowers open can improve fruit set where insects have limited access. Tap the support cane or string rather than crushing the flower truss. Keep doors open when possible so pollinating insects can enter, but do not rely solely on them. Do not hand-pollinate with wet fingers or use harsh sprays around flowers. If weather is persistently cold or very hot, shaking cannot fully overcome it; protect the plants, ventilate and wait for more favourable conditions. Healthy new trusses often respond better.
Keep roots evenly watered, particularly when plants are flowering and carrying fruit. Letting compost dry completely, then soaking it heavily, can cause stress and poor fruit set. Check pots daily in warm weather, water thoroughly when needed and ensure excess water can drain. Larger containers give roots a more stable supply than very small pots. Feed tomatoes regularly once the first fruits begin to form, following the label of a feed suitable for fruiting crops. Do not overfeed early with nitrogen-rich materials, as this can produce lush leaves at the expense of flowers. Mulch greenhouse borders with garden compost to conserve moisture while keeping stems clear.
Review the season realistically and improve your next batch. Early-sown plants can flower before conditions are dependable, while late plants may run out of warmth outdoors. In milder southern gardens, outdoor tomatoes often have a longer window; in cooler or wetter regions, use a greenhouse, polytunnel or a warm wall. Choose varieties suited to your location and give each plant enough root space and sunlight. Remove only damaged or diseased-looking leaves, not healthy flower trusses. If the current truss fails, continue the routine of ventilation, gentle tapping and even watering. Tomato plants often resume setting fruit once a short weather spell passes.
Frequently asked questions
Should I shake tomato plants every day?
A gentle tap or shake around midday on dry days while flowers are open is enough for greenhouse cordon tomatoes. There is no need to shake hard or constantly. If temperatures are unsuitable or roots are very dry, vibration alone will not solve the problem, so correct those conditions too.
Can too much heat stop tomatoes setting?
Yes. Very hot, humid glasshouse conditions can reduce pollen viability and make pollination less effective. Ventilate early, open doors and vents, provide temporary shade during exceptional heat and water roots consistently. Once temperatures become more moderate, later flowers often set normally without any drastic intervention.
Why do outdoor tomatoes lose their first flowers?
Early outdoor trusses can meet cold nights, wind or unsettled weather just after planting. A small amount of flower drop is common and later trusses may perform better. Give plants a sunny sheltered site, avoid drought, protect them during chilly spells and do not judge the season solely by the first flowers.
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.