Due to popular demand a post on retting:
In the above picture the light, beige coloured stalk in the middle has retted much faster than the others and has dramatically ‘balded’ ie. the fibres have rotted away completely. This should alert you to the fact that the others may soon be doing similarly and the batch may need lifting. The discolouration of the other stems is completely normal and if ‘retting’ in very wet weather a black, fungal type discolouring may be quite extensive. However, this discolouration usually occurs most visibly once the stems are nearing completion, so be vigilant in looking for signs of ‘balding’.
Here you can see where the fibres have rotted away completely, leaving bare stem. Watch out for slugs and snails – they too can create ‘balding’, munching right through the bast.
The centre stem has been over ‘retted’ but the other stems largely still look fine, but I would probably lift them all now.
Basically, don’t work to a set time like 2 weeks or 3 weeks. Every stalk, in every bundle is slightly different, so whether it takes a few days or a few weeks, you need to keep checking the stems aren’t ‘balding’ as that indicates that fibres have been lost.