There are more than 900 species and innumerable cultivars of azaleas and rhododendrons. However, only a small number perform well in Iowa. To be successful, the Iowa gardener must select cold hardy cultivars, choose suitable planting…
American holly (Ilex opaca) and English holly (Ilex aquifolium) are prized for their glossy, green leaves and brightly colored fruit. Sprigs of both hollies are often used in wreaths, centerpieces, and other Christmas…
Ash trees infected with emerald ash borer (EAB) do not need to be treated or chipped when removed. If you do plan to keep the wood for campfires or fireplaces use it on your property and do not transport the wood to new locations. Any…
Remove suckers with a hand pruners as soon as they appear from their point of origin. Often this requires pulling a little bit of soil back to find the base and clip it off while still less than 6 to 12 inches in length. If suckers…
This is a difficult question to answer because the growth rate of any plant depends on site conditions and maintenance. In most cases, the growth rate given for a particular plant is based on optimal conditions. Quite frequently, however, our…
The majority of roots, especially those roots that are responsible for water and nutrient uptake, are in the upper 6 to 18 inches of soil. Structural roots that radiate out from the tree and provide support and anchorage can reach a…
Fruit trees purchased from nurseries and garden centers are usually 1- to 2-year-old plants. The length of time from planting to fruit bearing varies with the species of fruit, the cultivar, and whether the tree is dwarf or standard.…
Shedding bark on some trees is a completely normal development. The bark of most young trees is smooth and thin. As the tree grows, the bark layer thickens with the outermost tissue eventually dying. Continued growth pushes the bark outward,…
Purple, black, and summer-bearing red raspberries that have been badly damaged by rabbits will likely produce little fruit this year. (Purple, black, and summer-bearing red raspberries produce fruit on the previous year's shoots. …
Fire blight is probably responsible for the wilted shoots on your crabapple. Fire blight is caused by the bacterium Erwinia amylovora. Plants susceptible to fire blight include apple, crabapple, pear, hawthorn, and…
The growths on the pin oak are a type of gall. Galls are abnormal growths of plant tissue induced to form by mites, insects, or other small organisms. The galls on the pin oak are called horned oak galls because of the horn-like…
Ash rust is probably responsible for the orange growths on your ash tree. Ash rust is caused by the fungus Puccinia sparganioides. The fungus produces conspicuous swellings on leaves, petioles, and twigs. Infected…
The Emerald Ash Borer (EAB) is an exotic destructive pest that kills all native ash trees (Fraxinus). The loss of ash trees significantly impacts the urban tree canopy. While treatment options are available, some trees cannot be treated…
Cherries perform best in moist, well-drained, fertile soils. Avoid wet, poorly drained sites. Cherries are susceptible to root rots in wet, poorly drained soils. Trees should also receive full sun. Sites must receive at…
Modern roses, such as hybrid tea, grandiflora, and floribunda roses, are propagated by budding. A single bud is removed from the desired variety and inserted onto a hardy rootstock. The bud union (the knob-like swelling at the base of…
Gooseberries and currants are small to medium-size shrubs that may reach a height of 3 to 6 feet. Gooseberries and currants should be planted 4 to 5 feet apart. Rows should be spaced 6 to 8 feet apart.
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…
When plants produce a chemical that prevents the growth of other plants, it is called allelopathy.
Black walnut is a common woodland and landscape tree in the Midwest that produces an allelopathic compound called juglone which is…
While most deciduous trees have flowers of some kind in springtime, they tend to be small and not showy. There are several species of smaller, ornamental trees that have showy blooms in the spring.
Noticeable symptoms of emerald ash borer usually appear in the second or third year of the infestation or later. Emerald ash borer infested trees exhibit thinning of the leaf canopy and dieback in the crown. Also, infested ash trees…
Forsythias bloom on the previous year’s growth. The best time to prune forsythias is immediately after flowering. Pruning forsythias anytime from mid-summer until just prior to bloom will reduce flowering in spring. When pruning…
Weigelas bloom on both old and new wood. Plants bloom heavily in late May or June on the previous year’s growth. They also bloom intermittently through the summer on the current season’s growth.
Summer-flowering shrubs, such as potentilla and Japanese spirea, bloom in summer on the current year’s growth. Prune summer-flowering shrubs in late winter or early spring (March or early April in Iowa).
Azaleas in the Northern Lights Series possess excellent cold hardiness and perform well in Iowa. (The Northern Lights Series is a group of hybrid azaleas developed and released by the University of Minnesota. All cultivars in the series…
