Cork is harvested in a steady cycle that promotes healthy growth to the tree over its expected lifespan of over 200 years.

Typically, virgin cork is not removed from saplings until the 38th year (in Portugal), and reproduction cork (the first cycle) may not be extracted for another 9-12 years.
Cork suitable for wine stoppers is not harvested until the following 9-12 year cycle, so farmers have invested over 40 years before natural wine corks are produced.
The first harvest produces cork of a very irregular structure. This is called 'virgin cork'.The second harvest brings 'reproduction cork' - a material with a more regular structure, less hard, but still not suitable for cork stoppers.
'Reproduction cork' is usually granulated for use in products such as flooring.

It is from the third and subsequent harvests that the cork with the best properties is obtained - the 'amadia cork' - and from this time, the tree will provide good quality cork for about 150 years.
This is the type of cork that is used on wine stoppers.