Ten Weeks Dwarf Stocks Seeds. Double florets often begin blooming when the plant is only 15 cm (6") tall and continue all season long. Mature plants average 30 cm (12") in height. Intoxicating fragrance emits from flowers in shades of pink, red, mauve and white - a must for every garden. Stocks seem to have a natural preference for growing conditions in southern Ontario. Although a hardy annual by nature, blooms are adversely affected by frosts. May self sow and persist of its own in mild climates.