Q: Ever wondered when is the right time to harvest potatoes?
A: When you need the space they’re in for something else. What other measure of their readiness could there possibly be?
Wait, there is another indicator of when they’re ready: when you curse aloud every time you go to the greenhouse because one of the planters full of potatoes is getting in your way. It’s particularly annoying after a thunderstorm when the foliage is wet and soaks your legs on your way past.
It’s particularly satisfying to empty a planter, find some beautiful new potatoes…
…And then immediately plant out some courgette plants into those same planters. (Having first moved them so they are no longer in the way and thus less likely to be curse-inducing.)