Achillea filipendulina. The classic golden-flowered Yarrow is an old-world herb that grows to a height of 120cm (47″) making it a focal plant in the middle or back of flower beds. Yarrow Achillea seeds yield brilliant yellow 15 cm (6″) flowers that bloom from late June to September. Yarrow is a highly drought-resistant plant, so excellent for xeriscaping. Use it as a companion plant in the vegetable garden, too – its scent repels aphids, but attracts hoverflies, ladybugs and wasps that feed on common garden pests. Enzymes in Yarrow help to break compost down swiftly. Simply cut stalks down at the end of the season and breaking them into manageable pieces to be added whenever you top up the compost heap.