Slowing the summer bolt to seed

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.