Rotten courgettes, lack of calicum? How may times do I need to give my courgettes calicum?
Blossom end rot is a common issue when growing zucchini (squash), as well as tomatoes, and yes, this is due to a calcium deficiency. The best way to add calcium to your garden is with compost, as most compost is fairly rich in calcium (which the addition of lime or eggshells to your pile can ensure). You also don't need to worry about over applying calcium, which is another common issue. Another approach to adding calcium is to find an organic calcium foliar spray that you can spray directly on the plants (follow the directions). Generally, you only need to add calcium on an as needed basis.
These articles should help: https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-and-calcium.htm
My marrows and courgettes grow to about 4 inchesthen suffer from end rot, those that do survive will not grow any bigger than 5inches I always polinate them but this does not make any difference .the soil PH is 7. 0
This article may help with the ens rot:
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-blossom-end-rot-causes-and-treatment.htm
I have a plant growing in my garden that I did not plant. I think it came from a pack of bird seed. When I first saw it, I thought it was a courgette, but then it started trailing along the ground and now has climbed up my fence. It is very big and has big yellow flowers and a round fruit, but the flowers keep dying and then the 'fruit' rots and drops off when it gets to the size of a golf ball. Do you have any ideas?
It is most likely a pumpkin. They frequently become volunteer plants due to their use at Halloween. The birds eat the discarded seeds from the trash and sometimes drop them as they are flying or a pumpkin ends up in the compost pile and a seed survives and is "planted" when the compost is spread. The fruit rotting and dropping off is likely due to poor pollination.
I have successfully grown courgettes for a number of years without problems. This year all the plants died practically overnight, I think because of an infestaion of vine borers. How can I prevent this happening again?
It's best to treat the vines when they are young. Here's how:
https://www.gardeningknowhow.com/edible/vegetables/zucchini/vine-borers-zucchini.htm
How big does a courgette have to be, that its seeds are viable to sow?
It's a good question, but I don't think the size of the fruit is necessarily the determining factor for harvesting viable seeds. "Courgettes," also known as zuchinni squash, are usually harvested while they're small and tender. I'm attaching a link to a great article about squash seeds.
https://www.gardeningknowhow.com/edible/vegetables/squash/squash-seed-harvesting.htm
There is a specific process involved that should help you determine which seeds are viable.
my courgette has got brown leaves and the leaves have gone brittle. all the other leave a green
Unfortunately, your photo did not come through. I am unable to see the damage.
In the meantime, this article will offer some insight:
https://www.gardeningknowhow.com/edible/vegetables/zucchini/zucchini-squash-diseases.htm
I have 3 x 3 courgette plants in a tub and they are getting bigger by the day. They are starting to flower etc and I don't know whether I should be planting them out or leaving them in the tub?
Ultimately, this is up to you. They may produce more in ground, but the spot must be prepared to plant, beforehand. As well, make sure not to disturb the root system while you are transplanting.
https://www.gardeningknowhow.com/edible/vegetables/zucchini/growing-zucchini.htm