The bright yellow flowers of forsythia are a spectacular sight in the spring. Unfortunately, many of the forsythia varieties that have been widely planted in past years, such as 'Lynwood Gold' and 'Spring Glory,' don't bloom reliably in Iowa. Their flower buds are often killed by low winter temperatures. Home gardeners wishing to plant forsythia should choose varieties that possess excellent flower bud hardiness. The following varieties should bloom reliably in Iowa each spring.

An excellent forsythia for Iowa is 'Sunrise.' 'Sunrise' is an Iowa State University introduction that has bloomed well after temperatures of -20oF. It is a semi-spreading, compact shrub with a mature height of 5 feet and a similar spread. The leaves are medium green. In cool, dry fall weather the leaves may develop a purplish cast. Young stems have 4 longitudinal ridges which give them the appearance of being square. While the bright yellow flowers are relatively small, the large number of blossoms per branch results in a mass of color. The compact habit of 'Sunrise' makes it ideal for small hedges or specimen plants.

Another hardy forsythia is 'Meadowlark.' Jointly introduced by North Dakota State and South Dakota State Universities, in collaboration with the Arnold Arboretum, 'Meadowlark' has consistently bloomed in both states. Flower buds have successfully survived temperatures of -35oF. Flowers are a bright yellow. A vigorous, rapidly growing shrub, it reaches 8 to 10 feet in height. 'Meadowlark' has dark green leaves. Under favorable conditions, the leaves often change to a golden yellow in the fall.

'Northern Sun' is an introduction of the University of Minnesota. Grown at the Minnesota Landscape Arboretum in Chanhassen, 'Northern Sun' has bloomed when temperatures dropped to -30oF. The clear yellow flowers cover the plant in early spring. Foliage is a medium green. The vigorous shrub reaches a height and spread of 8 to 10 feet.

Another hardy forsythia variety is 'Northern Gold.' A Canadian introduction, 'Northern Gold' is an upright shrub that grows 6 to 8 feet tall. Flowers are golden yellow.

These hardy varieties are available at many local garden centers and mail-order companies. For best flowering, plant forsythias in full sun.

This article originally appeared in the April 12, 2002 issue, p. 40.