Once established, a sturdy plant like yarrow … Starting Outdoors: Direct sow at last frost date. Second, yarrow crossbreeds vary readily, which means that if plants do self-sow, you could wind up with seedlings that have reverted to the parent types—likely the wild yarrow … When to Set Outside In spring, after last frost, or in early autumn. Germination is slow with yarrow … Yarrow is a tough, adaptable perennial that blooms in a variety of colors including yellow, white, pink, red and more. However, if a dry spell is prolonged, please water it rather than test its tolerance. Yarrow may mine copper from the subsoil, which is an important micronutrient for plant growth and an essential amendment for acidic soils. First, some of the common yarrow types self-sow freely, and leaving flowerheads in place can result in a yarrow takeover in the garden. Sow yarrow seed in a commercial seed starting mix that’s designed to get seedlings off to a solid start. Learn how to grow yarrow plants and get care tips, plus find the best varieties to plant in … According to Gaia’s Garden , however, plants that … Barely cover yarrow seeds. Yarrow seeds need some light to germinate. Growing Tips. Aim for one-quarter inch of soil at most. Once established, yarrow is a water-wise, drought-resistant powerhouse. Placement & Cultivation Yarrow is used for xeriscaping—great for rock gardens, meadow …