All varieties of the common garden impatiens (Impatiens walleriana) and interspecific hybrids with an Impatiens walleriana parent (such as Fusion and Butterfly impatiens) are susceptible to Impatiens downy mildew. Garden balsam…
The most widely grown rhododendrons in Iowa are the Weston hybrids. Introduced by the Weston Nursery in Massachusetts, these cultivars possess excellent cold hardiness. Weston hybrids include ‘PJM’ (lavender pink flowers), ‘PJM…
A key to successfully growing grass in shady areas is to select the proper turfgrass species for the site. Kentucky bluegrass is the most widely grown turfgrass in Iowa. However, most Kentucky bluegrass varieties do not perform well…
Most vegetables require at least 6 hours of direct sun each day to produce a good crop. Leafy vegetables, such as leaf lettuce, spinach, collards, Swiss chard, and kale, can be successfully grown in areas that receive 3 to 4 hours of sun.…
Newly planted rhubarb will initially produce small, spindly stalks during its 2 year establishment period. The stalks of large, old plants may be small and spindly because of overcrowding. Poor plant vigor due to poor cultural…
Snow molds may be responsible for the brown spots in your lawn. Two snow mold diseases, gray snow mold and pink snow mold, occur in Iowa. Gray snow mold is caused by two species of the fungus Typhula, while pink snow mold is…
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…
Flower development is natural for rhubarb and most other plants. Drought, extreme heat, and infertile soils may encourage flowering. Age is another factor. Old plants tend to flower more than younger ones.
The leaf drop is likely due to anthracnose. Anthracnose is a common fungal disease of sycamore, ash, maple, oak, and other trees. Anthracnose is most severe in years with cool, wet spring weather. While anthracnose may cause extensive defoliation…
If the daffodils aren’t blooming, the plants weren’t able to store enough food in their bulbs in the previous year. Daffodil foliage typically persists for 4 to 6 weeks after blooming. During this 4 to 6 week period, the daffodil…
A crabapple is a type of apple. The main difference between an apple and a crabapple is the size of the fruit. A crabapple is a tree that produces fruit that are less than 2 inches in diameter. An apple tree produces fruit that…
A late freeze in spring may damage the blossoms or developing fruit on apples, cherries, and other fruit trees. As a result, the fruit crop may be smaller than normal. The extent of damage will be determined by the plant species,…
Advertisements for gypsum sometimes claim that gypsum will help loosen heavy, clay soils and improve soil drainage. However, the addition of gypsum to Iowa soils is of little benefit. Gypsum is chiefly used to amend sodic soils. Sodic soils are…
One of our biggest frustrations with moles is the perennial misinformation that an insecticide application to kill grubs will solve the mole problem. This is the “lie that will not die.” Forty years ago, it might have been true that…
Freezing temperatures don’t harm dormant plants. In some years, warm late winter temperatures can cause some fruit trees to break bud, leaf-out, or develop flower buds earlier than normal. The inevitable below-freezing temperatures that…
In some years, warm late winter temperatures can cause some trees and shrubs to break bud, leaf-out, or develop flower buds earlier than normal. The inevitable below-freezing temperatures that follow in early spring can potentially cause…
Beans produce perfect and self-fertile flowers so they readily and easily pollinate themselves. Only beans in the same species are capable of cross-pollinating. So, pole beans (Phaseolus vulgaris) can cross with other varieties of bean…
Cool-season annuals are annual plants that prefer cool temperatures, growing best in spring or fall. Many are tolerant of a light frost often surviving down to 28°F or sometimes even 25°F with little damage to flowers or leaves.
