Advice
RHS Help & Advice
Pollination of tender glasshouse crops
Tomatoes, peppers and aubergines have ‘perfect’ flowers, containing both male and female parts. The flowers only require slight movement to dislodge pollen from the anthers to the stigma for pollination, so plants can be gently shaken to guarantee perfect pollination.
Alternatively, watering overhead with a fine rose has the added advantage of also raising humidity levels. A dry atmosphere during flowering and fertilisation can cause pollination failure or fruit malformation, as can very high or low temperatures. Open or close the glasshouse as required to keep the temperature regular.
Courgettes,
ridge cucumbers and melons are monoecious - i.e. they bear
separate male and female flowers on the same plant. In periods
of cold weather hand pollination may be required as pollinating
insects will be scarce. Indoor crops and those under cloches
should be kept accessible to insects during the day.
Courgettes are sometimes produced with withered tips - a sign that pollination was incomplete.
Greenhouse cucumbers are parthenocarpic - i.e. female flowers do not need to be pollinated to produce fruit. If flowers are fertilised bitter compounds develop within the fruits. If possible grow modern all female F1 cultivars which don’t produce male flowers. Alternatively, male flowers must be removed from old types.