The leaves have all the power - so I use the leaves.

The sheep sorrel plant used for medicinal puropses is a small plant. Each plant can be harvested of its leaves spring, summer and fall - just take the mature leaves and leave the little ones to mature.

The roots are taken in the winter - after the plant has "dies".

SO - it just depends on how many plants you have and which ones will be big producers and which ones will not. If you get some really healthy producers - save their seed and replant - or separate the youngs shoots.

Sheep sorrel is very easy to grow and can get invasive if you don't keep it in a contained area - after all - it is a "weed".

P.S. - The more sour it is - the stonger it is for medicinal use.