Nothing will grow in one area of my lawn. I've tried shrubs and perennials multiple times and watered when needed, but they still die. How do I test for a toxin in the soil?
When testing for a plant toxin, you must specify which one. That's impossible in cases like this. In any case, such tests are expensive. However, you can do a simple home test by planting annual ryegrass seed in two containers, one filled with suspect soil and the other with healthy soil. Observe for a week after germination. Reduced germination or stunted growth in the suspect soil indicates that it might be contaminated, and you might want to replace it with healthy topsoil or cover the area with mulch to prevent soil erosion. Also, if there is a walnut tree nearby, its root toxins could be causing your problem.
I am wondering how much floating row cover I will need this summer. Will any of the following die off in this cold winter: Mexican bean beetles, squash vine borers, cucumber beetles, whiteflies or marmorated stink bugs?
Except for whiteflies, the pests you mention survive the winter in soil or protected locations in plant residues, leaf litter, and weeds or trees. They are also well-adapted to our climate. There may be limited kill-off, but they've survived tough winters before. Whiteflies, however, cannot overwinter outdoors in Maryland — people bring them into their gardens each year on purchased transplants. So before you buy, inspect leaf undersides for tiny eggs. Row cover is great stuff. You may also be interested in trying micromesh — available, for example, from Territorial Seed Company — which excludes small insects but will not trap excess heat in midsummer like typical row covers do.
University of Maryland Extension's Home and Garden Information Center offers free gardening and pest information. Call 800-342-2507 or send a question to its website at extension.umd.edu/hgic.
Plant of the week
Apostle plant, walking iris
This is probably one of the easiest plants to grow — both indoors and out — and one of the oddest. Its 12 sword-shaped leaves appear as a fan. Each leaf develops an exotic flower like a cross between an iris and an orchid. The flower lasts only one day, but the numerous blooms continue throughout spring, summer and fall. A stem with a plantlet dangling on the end grows from the flower. Like spider plants, the apostle plant is ideal for a hanging basket. In its natural environment, the plantlet makes contact with soil and roots, hence the name "walking iris." To propagate new plants indoors, root plantlets in pots for several weeks, then snip the stem connecting them to the mother plant. Adaptable to most any light or soil condition, the apostle plant takes care of itself.
—Bob OraziCopyright © 2015, The Baltimore Sun