Lamb's quarter and Sow thistle help melons, squashes, and cucumbers. Lupine helps corn and many other crops. Small amounts of Yarrow and Valerian give vigor to vegetables. Wild mustard is beneficial to grapevines and fruit trees. Dandelions stimulate fruits and flowers to ripen quickly.
Stinging nettle makes neighboring plants more insect resistant.
And the iron content of nettle helps plants withstand lice, slugs, and snails during wet weather. Mint and tomatoes are strengthened in their vicinity. Nettle deters fermentation, keeping fruit trees free of mold. Redroot pigweed loosens soil for root crops such as carrot, radish, beet, and potatoes. It makes tomato, pepper, and eggplant more resistant to insect attack.