10cm, Rose Wood Shamrock is an herbaceous North American perennial with showy bright rose to lilac-rose flowers above bluish green leaves. Makes dense floriferous carpets in early spring before deciduous trees unfold their leaves. Easily grown in any humus rich, slightly moist soil in partial shade to full sun. First flowers to be expected one year after sowing. Sow seeds flat in any rich, well drained soil and keep pots outside during winter. Seeds require a prolonged cooling period after sowing and will germinate in mid spring the following year. USDA Climate Zone 6. III-IV.