Leave it in Spanish. You can explain it then if you like:

crianza
[kree-AHN-zah]
The Spanish term meaning "breeding" or "upbringing." "Con crianza" or "vino de crianza" on a wine label refers to the AGING a wine receives. The exact rules are defined by the governing body of each DENOMINACION DE ORIGEN (DO). If a DO has no specific rules, a crianza wine must receive a minimum of 2 years aging either in a tank, an oak barrel, or a bottle. Many of the DOs require that 1 of the 2 years be in oak barrels. By contrast, red RESERVA wines require a minimum of 3 years of aging with at least 1 year in oak barrels; ROSÉ and white RESERVAS require a minimum aging of 2 years with a no less than 6 months in oak barrels. The words Sin crianza on a label indicate that the wine did not receive minimum aging and was bottled young.

http://www.epicurious.com/drinking/wine_dictionary/entry?id=...

Specific to Rioja:

Vino de Crianza: Wine in its third year, matured for at least one year in oak cask.
http://www.riojawine.com/en/vinosbodegas/tipos.htm