Frequently Asked Questions
In Iowa, Kentucky bluegrass lawns can be fertilized in spring (April or May), mid-September, and late October/early November. The number of fertilizer applications is largely determined by an individual’s desires or expectations for their...
Red and purple raspberries are hardy throughout the state. Black raspberries, however, often suffer severe winter damage in northern Iowa and can be reliably grown only in central and southern portions of the state. ‘Black Hawk’ (an...
Dig a hole that is 2 to 3 times wider than the diameter of the tree’s rootball. The depth of the hole should be 2 or 3 inches less than the height of the rootball. Slope the sides of the hole so the top of the hole is several inches...
The horizontal circular webs were created by various spiders collectively called grass spiders. They are harmless to the grass and ecologically beneficial as predators. The webs accumulate between rain showers and mowings. They...
The fruit of the muskmelon or cantaloupe is mature when the stem slips easily from the melon with slight pressure. The melon is not ripe if the stem has to be forcibly separated from the fruit. Other indicators of maturity are based...
Bagworms are caterpillars that live inside spindle-shaped bags. (The bags somewhat resemble small Christmas tree ornaments hanging from the tree.) Bagworms feed on the foliage of a wide variety of trees and shrubs. However, they...
Martha Washington or regal geraniums (Pelargonium x domesticum) produce beautiful flowers. Unfortunately, cool (50 to 60°F), night temperatures are required for flower formation. Few flowers form during the summer...
Harvest roots when 3 to 5 inches in diameter. The foliage may also be harvested for greens. Prior to storage, trim off the foliage to within 1 inch of the crown with a sharp knife. Also remove the tap root. Rutabagas...
It’s common for the acorn crop on oak trees to vary from year to year. Most oak species produce a good crop of acorns once every two or three years. However, the white oak tends to produce a good acorn crop once every four to six years....
Peonies perform best in full sun and well-drained soils. When selecting a planting site, choose a location that receives at least 6 hours of direct sun each day. Avoid shady areas near large trees and shrubs. Poorly drained...
Foliar diseases of tomatoes are a common problem in the home garden. Fungal diseases, such as early blight and Septoria leaf spot, overwinter on plant debris in the soil. Fungal spores are splashed onto plant foliage by raindrops or...
The “hedge apple” is the yellow-green, softball-sized fruit of the Osage-orange (Maclura pomifera). The Osage-orange is a small- to medium-sized tree. It commonly grows 25 to 30 feet tall. The Osage-orange is dioecious...
The best time to divide perennials varies with the different plant species. While most perennials are best divided in early spring, late summer/early fall (September in Iowa) is a good time to dig and divide peony, daylily, garden phlox, hosta,...
Harvest garlic when the foliage begins to dry. In Iowa, garlic is usually harvested in August or September. Carefully dig the bulbs with a garden fork or shovel. Dry the garlic in a warm, dry, well-ventilated location. ...
Early in the 1900's, white pine blister rust (Cronartium ribicola) became a serious disease problem in the United States. White pine blister rust requires both a currant or gooseberry (Ribes species) and white pine to...
Grape hyacinths (Muscari spp.) are spring-flowering bulbs. They produce urn-shaped flowers on 6- to 9-inch-long, upright spikes. (The flower spikes somewhat resemble clusters of grapes, hence the common name.) Flowers...
Do not mow shady areas less than 3 inches in height. Because of the lower photosynthetic rates in shady areas, the turfgrass plants need a large leaf surface to manufacture adequate amounts of food. The recommended mowing height for...
Dead raspberry canes will be white to gray in color. When dead canes are pruned, the tissue inside the stem will be tan to brown and dry. Live canes will be brown to purple in color. The tissue inside the stem will be white to...
When planting a container-grown tree, dig a hole that is 2 to 3 times wider than the diameter of the container. The depth of the hole should be 2 or 3 inches less than the height of the soil ball. Slope the sides of the hole so the...
The orange color is likely due to rust. Rust is a fungal disease. It can be diagnosed by walking across the lawn in white shoes. As you walk across the lawn, bright orange spores of the rust fungus will rub off onto the shoes,...
Unlike muskmelons, the fruit of honeydews do not slip off the vine when mature. The best indicator of ripeness is a slight softening of the blossom end of the fruit. There may also be a subtle change in the color of the honeydew....
The “worms” are likely fall webworms. Fall webworms are hairy, tan to yellow caterpillars. As they feed, fall webworms construct tents or webs at the ends of branches. Tents are initially small, but the caterpillars enlarge the...
Symptoms of impatiens downy mildew initially appear as yellowing of infected leaves. The yellow-green foliage may initially be confused with a nutritional deficiency. As the infection progresses, leaves may curl downward and a white, fuzzy growth...
Radishes can be planted as soon as the ground can worked properly in spring. This is often late March in southern Iowa and mid-April in northern counties. Successive plantings can be made every 7 to 10 days through May. Radish...
In Iowa, the foliage of the river birch (Betula nigra) often turns a sickly yellow-green. The yellow-green foliage is due to a deficiency of iron. The problem is referred to as iron chlorosis. (A close examination of chlorotic leaves...
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