Seeds from this Malva sylvestris Primley Blue An excellent variety for season long color, this striking mallow displays powder blue, violet veined blooms from early summer until early fall. Growing 30 inches tall, this is one of the toughest Malvas for my hot humid summers. Difficult to germinate needs patience and not too much water. This zone 4 to 9 perennial should only be grown in full sunlight. It does best in average to evenly moist conditions, but will not tolerate standing water.