Grower’s Corner – courgettes and summer squashes
It’s quite shocking to realise that until very recently, say the last twenty years, you never saw courgettes in British vegetable garden, only thick skinned marrows. However, these days there are plenty of varieties to choose from and the plants themselves come in two types: the vast majority grow as relatively compact bushes, but there are a few climbing or trailing varieties (try Tromboncino or Black Forest) which can be trained up supports or over archways to make a pretty and productive summer annual.
Seed can be sown in three inch pots filled with compost from March to the end of May. Sow a seed on its side about an inch deep and place in a propagator or on a windowsill. When roots begin to show through the bottom of the pot, move into a five inch container and then into growing bags, soil or a large pot in late spring or early summer. If you have a sheltered sunny spot, you can sow seed directly into the soil from late spring to early summer. For outdoor sowing, put two seeds on their sides an inch deep and about an inch apart and when they’ve germinated, take out the weakest one.
Loads and loads of water is essential, especially when the plants are in flower and the fruits have started to swell and if possible mulch to lock in moisture. If you dug in plenty of manure before planting, additional feeding is unnecessary on heavy, fertile soil but on sandy or light soil, regular drenches with a liquid feed will help boost production.
Problems
Courgette rot is caused by bad early summer weather with a prolonged cold spell. This can mean few insects are around which leads to poor pollination and the infant courgettes fail to develop, rotting swiftly on the plant. When the weather starts to improve, so will the crop, but you can pollinate the earlier batch of flowers by hand, rather than relying on insects. Pick an open male flower (which doesn't have a swelling at the base) and strip off the petals to expose the stamens and pollen which you rub thoroughly against the stigma of a female flower (which has a swelling or an immature fruit at its base).
Harvesting
The correct size to pick depends on variety, but as a rule, harvest courgettes when they are about four inches round and use a sharp knife to sever the fruit from the plant, never pull or tug. Courgettes do not keep well because of their high water content. Squashes are more variable in shape and size, so read the seed packet for harvesting and storage information, they keep much better than courgettes.
Top tips
- To keep plants productive you need to harvest courgettes about three times a week at the height of the season
- Marrows are often viewed as nothing more than courgettes grown large, and require the same growing conditions. When growing marrows, harvest regularly when they are eight inches long, or leave them to mature for winter use. Marrows, with their thicker skins, can be stored for a long period of time if kept at a cool temperature in an airy place.
Courgette flower and summer squash photographs by cattypumkinhead and ilovebutter, used under a creative commons attribution licence