Q: I have heard that there are certain weeds that can inform you about the soil quality. Is there anything to this?
Answer: Yes, plants can serve as indicators of soil conditions. Plants have specific growing requirements, including soil type, condition in relation to water, pH, sun, shade and temperature zones. Successful gardens and landscapes result from the proper cultural needs of the plants being met. The plants that we consider as weeds have the same requirements. There is a phrase we like to use in landscape horticulture: “the right plant for the right place.” The following are some examples of soil indicator weeds. Soils that stay dry will host goose grass, annual lespedeza, prostrate knotweed, bracted plantain, and yarrow. Soils that stay wet will host moneywort, annual bluegrass, alligatorweed, pearlwort, moss, liverwort, rushes, sedges, plantains, oxeye daisy, meadowsweet, docks, coltsfoot, henbit, woodsorrel, and dollarweed. Soils with low fertility will host broomsedge, hawkweed, clover, chickweed, speedwell, black medic, chicory, bitter sneezeweed, crabgrass, and common mullein. In high fertility soils, you will find annual bluegrass, ryegrass, pigweed, lamb’s quarter, and moss. Acidic soils will host silvery cinquefoil, common sheep sorrel, red sorrel, plantain, oxeye daisy, nettles, common mullein, moss, knotweed, horsetail, docks, and coltsfoot. In alkaline soils, you will find pennycress and broad plantain. A soil that is high in salinity will host shepherd’s purse. To learn to identify these common weeds, use a good field guide or Extension resources which can be found here: https://weeds.ces.ncsu.edu/weed-identification.
Q: I have holes in the leaves of my broccoli, cabbage and collards. Is there anything I can do about this?
Answer: The cabbage looper and cabbage worm moths are busy laying eggs on the leaves of your brassica plants. Once the eggs hatch, worms are munching the leaves. Make a pass through your garden looking for the eggs and worms on the leaves and mash any that you find. Then you can use a Bacillus thuringiensis (Bt) product on the leaves to control the worms. Bt is a naturally occurring bacterium that is safe to use in your home garden for worms. It is considered an organic pesticide. It will be available as a powder or a liquid. Use gloves when mixing and applying and protect yourself from breathing in any of the dust. Always follow the directions on the label.