I’ve been musing about something I’ve noticed over the past 2 years about green leafy herbs. Specifically, parsley, coriander and basil.
A few months ago I sowed a few separate patches of continental parsley at the same time. One was in full sun on the south-most corner of Bed A. The other was right up against the house in Bed B, getting only a few hours of sun per day. I would have expected that the parsley in full sun would be more prone to bolting to seed, but quite the opposite has happened.
Here is the patch out the front in full sun.
And here is the patch in part shade. It’s bolting.
The difference is water. The one out the front gets water from the tap when it drips, whereas the other only gets the rain (and when I think to water it).
I observed the same thing with my potted coriander. Going along quite happily until it dried out for a very short time, then wham! Off to seed.
So my new theory is this (probably bleeding obvious to those who have a clue about these things):
Stress of any form (heat, water, transplanting, lack of nutrients etc) will cause bolting. That’s why coriander seedlings also fail – transplant shock sends them straight to seed.
Has anyone tried growing coriander in a self-watering pot? Do you get longer out of it? I think I’ll try it, and also be sure to keep it well fertilised. I’m getting confident that I might be able to grow coriander more successfully in summer that way.
500m2 in Sydney 
Never tried growing anything in a self water pot. I just assume I won’t have cilantro during the summer. I do freeze it and that works.
That’s probably sensible Daphne! I guess when you get snow for a portion of the year you need to accept that sometimes stuff just isn’t possible. Maybe I should just be more realistic and concentrate on the seasonal crops! 🙂
If you let cauliflower or broccoli seedlings get too big and stressed before transplanting them, they tend to immediately go to seed and produce small button heads. Six weeks from sowing the seed in a pot, with an intermediate step of transplanting the tiny seedlings into a big seed tray, to planting outside is enough. Any more than six weeks and you are entering the danger zone. At least that is my experience.
I haven’t tried to grow coriander in summer neither. My pear is suddenly flower out of the season due to the heat stress so I think it is the same concept from your experiment.
I didn’t know that David – helpful observations!
Very helpful observations! I have only tried coriander one season and had such little success with it that I decided to give up and buy it. But your idea of a self-watering pot might do the trick? Although I doubt that with this crazy summer coriander will work no matter how much water you can give it! Devastatingly hot today in Sydney – hotter than even the inland! Stay cool if you can and may the cool change be a beauty!
Thanks Louise – it is lovely now. We have the windows open and the breeze is sweeping through – such a relief!