It concentrates potassium in the soil so good for compost heap. Tarragon - All purpose garden helper. Thyme - Attracts bees and deters cabbage worm so plant near members of cabbage family. Beneficial effect on plants near it. Valerian - Excellent addition to compost heap as stimulates phosphorous activity in soil.
Earthworms love it.
Wormwood - Grow by itself edge of garden as inhibits growth of other plants. Spray discourages slugs and snails. Yarrow - Increases essential oil content enhancing aromatic quality and making more resistant to insect attack.