Unusual dramatic and striking are words that will spring to mind when hollyhock 39nigra39 flowers in june and july its blooms grow on vertical stems and are notable for their dark maroon colour which appears almost black against the hardy perennial39s green foliage this althaea rosea can be grown in borders or be displayed in a vase with contrasting paler varieties in order to achieve the maximum impact height 2m 4063973441 spread 60cm 4023903441