Failte
The shamrock became a symbol of the Tua Cross among Celtic Druids before the Christian era and the shamrock was considered a sacred plant because it's leaves formed a triad. The number three was considered a mystical number in the Druid religion.
St. Patrick while preaching Christianity used the shamrock to explain the holy trinity, just as the shamrock is one leaf with three parts, so God is one entity with three persons, one each for the father, the son and the holy spirit thus making the shamrock a sacred plant.
Plant August to early November if you want shamrocks in time for St Patrick's day. Otherwise you can plant it anytime of the year.
Enjoy
St. Patrick while preaching Christianity used the shamrock to explain the holy trinity, just as the shamrock is one leaf with three parts, so God is one entity with three persons, one each for the father, the son and the holy spirit thus making the shamrock a sacred plant.
Plant August to early November if you want shamrocks in time for St Patrick's day. Otherwise you can plant it anytime of the year.
Enjoy