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 25th year, 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.

Cork bark is removed from trees in spring or summer. At this time of year the cork comes away easily from the trunk because the tree is growing, the new, tender cork cells being generated break easily. Harvest difficulties occur if the process is not carried out when the tree is in full growth. As soon as it is evident that the cork is being stripped too early or too late in the season the stripping is brought to a halt, a year’s delay in cork extraction is preferred to damage to the tree. 

There have been five consecutive below average rainfall years in the Mediterranean area. During drought periods the trees are less willing to relinquish their bark. During the ‘95 harvest, the window for stripping was quite narrow, adversely affecting cork yields. The good news is that the unharvested cork is stored for a greater than expected ‘96 harvest.

To keep the trees in good productive health, there are laws which regulate the harvest of cork oaks. In Portugal, trees are harvested every 9 years and on the island of Sardinia (Italy) the harvest occurs every 12 years. (Numbers are painted onto the bark to keep track of when a tree was stripped.) Therefore, harvest forecasting is based on 9 or 12 year cycles, i.e. projections for the ‘96 Portuguese cork harvest are based on the kilos harvested in 1987.

As land is being passed between generations, there is increased interest in forest management. There is an emphasis on creating balance in a tree, much like a grapevine, whereby a properly managed tree has the optimal balance of leaves, branches and cork for vitality. Additionally, cork producers have more active representation in the field and are continually working on increasing cork quality where it starts - in the forest.