How to pollinate courgette flowers by hand?

Courgette – Curcurbita pepo – of family Cucurbitaceae is a fruit eaten as a vegetable and harvested while still young when skin remains tender. Often cylindrical, it can sometimes be spherical, like the Courgette 'Ronde de Nice'. Iconic of summer, courgette is eaten in gratin, as velouté, braised, generally cooked, sometimes raw and grated. Sometimes your courgette young plants produce flowers but no courgettes. In that case it is necessary to pollinate flowers manually.

Why pollinate courgette flowers by hand?

Sometimes young courgettes yellow before ripeness and then drop from plant. Most likely cause is that flower was not pollinated. To remedy this long term, welcome biodiversity into garden, therefore pollinating insects. But short term, you can pollinate your courgettes yourself in your vegetable patch.

Technique is same when you want to produce your own seeds. Courgettes are, indeed, allogamous and favour cross fertilization with other varieties of same species via visiting insects. Manual pollination is therefore recommended to be sure to preserve characteristics of chosen variety.

Female and male courgette flowers on same plant.

When to carry out manual pollination?

During courgette growing season: May to August depending on your climate.

How to tell male from female courgette flowers?

Male flower is borne on slender peduncle. Peduncle of female flower, by contrast, looks already like a small courgette (see diagram below). In addition, male flower reveals a large, long stamen in its centre: this is part that bears pollen. Female flower presents short, rounded pistil: this is part that will receive pollen.

How to pollinate your courgette flowers?

1. Courgette flower opens for only one day! Therefore, spot female flowers to be pollinated and male flowers, which will provide pollen, at stage before flower opening: flower should be cream-coloured;
2. Using clothes pegs, tie male and female flowers to prevent them opening and insects from visiting;
3. Next morning, pick tied male flowers from first plant to pollinate female flowers of another plant of same variety;
4. Cut away corolla of male flower to reveal stamens that carry pollen;
5. Remove peg from female flower and gently open corolla;
6. Gently spread pollen from two to three male flowers onto stigma (pistil) of female flower: do this either directly by slightly crushing male flower onto pistil of female flower, or (better!) using a small brush or cotton bud. Please note: pollen from one male flower can fertilize several female flowers;
7. Tie corolla of female flower again with a clothes peg.