When to harvest

Hi All
I am really new to grow your own so please excuse my question   

How do you know when to harvest root vegetables? especially carrotts, potoatoes, beetroot and onions

Thank you
Jayne

Carrots: A good indicator is the size of the top of the carrot, you may have to brush away a bit of soil to see it. This is not guaranteed though you may have just a stump!

Potatoes: Earlies are generally ready for lifting when they've flowered, again you can brush away some soil (furtle!) to have a look. Maincrop - the foiliage needs to have died down.

Beetroot: You'll easily see them. I start pulling when they are golf ball size, but this is down to the individual.

Onions: They'll flop over of their own accord when they've had enough. They can be gently forked out of the ground, left in situ for a few days, they put somewhere really dry prior to storage.

Some of my onions have started to flower.
Should i take the flower off or should i pull them up?

Thanks for that - will do that later today!