Weeds That Warn of Worn-Out Soil
Biennial wormwood, common mullein, daisies, mugwort, wild carrot, wild parsnip, and wild radish are sure signs that your soil has poor fertility.
Luckily, many perennials actually flower better when the amount of food in the soil is on the lean side. This list includes achillea, antennaria, artemisia, asclepias, centranthus, cerastium, coreopsis, echinops, eryngium, gaillardia, salvia, santolina, solidago, and stachys. In the edible department, beans (and other legumes), beets, carrots, parsnips, peas, radishes, sage, and thyme tolerate soil that's low in fertility.
Of course, you could and should improve the fertility of at least some of that soil. First, have your soil tested. If the test reveals major deficiencies, correct them with organic fertilizers such as fish meal (for nitrogen), bonemeal (for phosphorus), and greensand (for potassium). From then on, use compost and cover crops to maintain your soil's fertility.
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