Frequently Asked Questions
Poinsettias are short-day plants. Short-day plants grow vegetatively during the long days of summer and produce flowers when days become shorter in fall. In order for poinsettias to flower for Christmas, they must receive complete...
Kentucky bluegrass lawns should be mowed at a height of 2½ to 3 inches in the spring and fall months. Mow bluegrass lawns at a height of 3 to 3½ inches in June, July, and August. A higher mowing height in summer helps to cool the...
After the last harvest, prune off the old fruiting canes at the soil surface. Remove the pruned material from the garden and destroy it.
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...
The loss of needles is probably due to seasonal needle drop. Deciduous trees, such as maple and ash, drop all of their leaves in fall. Though it largely goes unnoticed, evergreens also lose a portion of their foliage (needles) on a yearly basis....
September is the best time to divide peonies. By September, peony plants have been able to store adequate food reserves in their roots. Also, the replanted divisions have several weeks to get reestablished at their new sites before...
Gardeners should be able to begin harvesting tomatillos 75 to 100 days after transplanting. For best flavor, harvest tomatillos when the husk changes from green to tan while the fruit is still green. The size of the husk and fruit, as...
The brown streaks in the apples are probably due to the apple maggot. The apple maggot is the most serious insect pest of apples in Iowa. Apple maggot damage appears as knobby, misshapen fruit with small pits or blemishes on the fruit...
The foul-smelling objects are likely stinkhorns. Stinkhorns are a type of fungus or mushroom. The common name is derived from their appearance and smell. Stinkhorns usually appear in cool, wet periods in late summer and early fall.
Several...
Bell peppers are usually harvested when large, firm, and dark green (immature stage). They may also be allowed to fully ripen to red, yellow, orange, or other colors. Fully mature bell peppers are slightly sweeter and contain higher...
Jostaberries are a cross between black currants and gooseberries. Plants are vigorous and may grow to a height of 6 to 8 feet. Jostaberry fruit are similar in size to gooseberries and black in color. Plants possess excellent...
Florist or greenhouse mums are sold throughout the year at floral shops, supermarkets, and other retailers. Unfortunately, florist mums do not perform well when planted outdoors. Most florist mums will not survive the winter when...
Mowing frequency is based on the growth rate of the turfgrass and mowing height. As a general rule, never remove more than one-third of the total leaf surface at any one mowing. Shorter mowing heights require more frequent mowing. A lawn...
The small, purplish spots are most likely due to anthracnose. Anthracnose is a serious fungal disease of raspberries, especially black raspberries. The disease is readily recognized by the small, purplish spots that develop on young...
Prior to planting, soak the tree’s roots in a bucket of water for 1 to 2 hours. Also, prune off damaged or broken roots.
When ready to plant, dig a hole that is 2 to 3 times wider than the spread of the tree’s root system....
Late summer (mid-August to mid-September) is the best time to establish a lawn from seed in Iowa. Late summer seeding has several advantages over spring seeding. The seeds of cool-season grasses germinate quickly in the warm soil of...
Harvest when the underside or "belly" of the melon turns from a greenish white to buttery yellow or cream. This color change is especially pronounced on the dark green-skinned varieties. It is often less noticeable on lighter-skinned watermelons...
The black sooty material is likely sooty mold. Sooty mold is caused by several different fungi. The fungi don’t infect plants, but grow on the sugary honeydew excreted by aphids, scales, mealybugs, and other insects. In...
In landscape plantings, control of downy mildew on impatiens with fungicides is not practical. Sanitation is the best management strategy for this disease. Remove and destroy infected plants as soon as they are noticed to reduce the spread to...
Radishes can be harvested 3 to 5 weeks after planting. Periodically check their development by pulling one or two plants as they approach maturity. Harvest radishes when roots reach useable size (about 1 inch in diameter). ...
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