Growing courgettes

Posted: Monday 5 August 2013
by Adam Pasco

What a great summer it's been for courgettes. I struggled to get anything during the wet weather last year, but have made up for it this July.

What a great summer it's been for courgettes. I struggled to get anything during the wet weather last year, but have made up for it this July.

I've grown a few different varieties this summer, and the one pictured above is 'Zephyr'. As so often happens, it's the picture in the seed catalogue that sold this variety to me, as 'Zephyr' develops creamy-yellow skin with a green tip to each fruit. I thought it would offer something different to the usual green courgettes, and I haven't been disappointed. It's quite a spreading plant, but a great cropper.

When picked very small the fruits are firm and crisp - perfect for slicing thinly and sprinkling over salads - but haven't yet develop their green tips. This becomes more distinct as fruits swell, and they can reach a good size.

As with all courgettes, squash and marrows, plants produce both male and female flowers. As the picture shows, the flower on the right is female, with an immature courgette developing behind the flower, unlike the male flowers on the left.

With most varieties you need both, and then a helping hand from bees and insects to transfer pollen across from male to female to ensure fruit set. If female flowers don’t get pollinated the fruits can start swelling a little but then shrivel and die back from their tip.

During some summers the production of male and female flowers is out of sync - lots of male flowers, but not a female in sight, so no fruit.

It pays to grow more than one plant together to help insects transfer pollen between them, but where space is limited this often isn't possible. If only a single courgette plant is being grown then fruit set can be disappointing. In these situations I'd recommend growing the self-fertile variety 'Parthenon' - taking its name from the word parthenocarpic, meaning the production of fruit without fertilisation. With 'Parthenon' every female flower produces a fruit, so you're guaranteed a crop.

I've also grown the new, compact 'Patio Star' in large pots, and while one plant is cropping well the other has succumbed to a debilitating virus disease. Leaves show signs of mottling, failing to reach their full size, and crops are non-existent. Very disappointing. This has possibly been caused by cucumber mosaic virus or zucchini yellow mosaic virus.

There are some marrow varieties, like 'Tiger Cross' and 'Badger Cross', that have inbuilt resistance to cucumber mosaic virus, and I've had good returns from them in the past. Courgette varieties 'Defender' and 'Supremo' also show good resistance, and all these varieties have received an RHS Award of Garden Merit.

Plant breeders are doing good work developing courgettes that are compact rather than spreading, and produce spine-free leaf stalks to make picking easier. However, I love colourful yellow-skinned courgettes, so hope plant breeders are working on producing these too.

I'll wait until the end of summer to review the performance of all my courgettes, and next year carefully consider whether it's worth growing those that don't offer natural disease resistance. Which ones are cropping best for you?

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Amandathepanda 16/08/2013 at 09:03

I must be doing something wrong, my yellow ones have fallen off as they rooted, yet my patty pan squashes are doing great.

Susan Giles 16/08/2013 at 09:10

I've had problems with slugs early, but surrounded them with egg shells and that seemed to help. I've got four courgette plants growing and they are fruiting madly. They are pretty thirsty plants and I water them every day, sometimes twice a day when it is really hot, and feed them once a week. That seems to work.


Oh, I don't know if anyone else finds this, but I have found that my courgettes grow better in pots than in the ground. I planted one in the ground this year and it is not as far on as those in pots and not cropping as well either.

Welshonion 16/08/2013 at 16:13

If the small courgettes fall off instead of developing it is because they have not been fertilized.

Adam Pasco 18/08/2013 at 09:38

Yes you're right Welshonion, but growing the self-fertile variety Parthenon should help as every female flower will set fruit without needing to be pollinated.

Happy Flower 20/08/2013 at 12:17

I have been growing goldrush and defender courgettes. I too have had a superb crop from them growing in my new allotment- which is far better than when I grew them in pots last year- but the weather was terrible to be fair so it's probably not a fair contest.

Looking forward to next years crop already!

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