On 03/07/2020 18:51, David wrote:
On Fri, 03 Jul 2020 11:16:10 +0000, David wrote:

The courgettes (three different varieties) are fruiting, but the fruits
are not swelling fully.

The yellow one, for example, grows fruit to about 5" long but only very
slim.
They don't swell (an early one did part way along near the base) and
after a while go a deeper yellow which suggests that they are ripe.

I'm trying to work out if this is lack of pollination or just adverse
growing conditions.

I suspect a lack of male flowers. Seems to be a problem this year
possibly because it was so warm and dry last month.

They are grown in pots in a rich mix which started out with plenty of
nutrients, but I am about to start feeding.

I can't find out if lack of pollination lets the fruit grow long. Most
references suggest that the fruit will either be discarded or will rot
from the flower end.

One thing I have just noticed.

I can't see any male flowers on any of the plants!

Loads of female flowers and thin fruit, but not a male in sight.

This may explain the lack of swelling, but what explains the lack of males?

It seems to be a funny year. I have the same problem with only female
flowers on mine at present from the first flower. I'm hoping there are
some male flowers within range of the local bees or they may not set.

In normal years you get three or four male flowers before any females.
The plant needing to build up its reserves for making fruit.

--
Regards,
Martin Brown