Some of the first signs of spring have popped up – the daffodils, snowdrops, hyacinths and tulips are coloring the previously drab surroundings. In addition, spring flowering shrubs such as lilacs, rhododendrons, azaleas contribute to the blossoming landscape.
Lilacs are probably the most common spring flowering shrub in our environment. Their fragrant flowers bloom in many shades of purple, pink, magenta, violet and also in white. Depending on the cultivar they can range in size from five to 12 feet, and they bloom from early to late May. Over the years lilacs have become associated with blooming for Mother’s Day.
Other popular spring blooming shrubs in our zone 4 are rhododendrons and azaleas. Actually both of them are of the genus Rhododendron, but for the most part rhododendrons are evergreen and azaleas are deciduous. In some cases azaleas will bloom even before their leaf buds open. A popular rhododendron is the PMJ, named for its hybridizer P.J. Mezitt. This shrub has small dark green leaves, which are evergreen, and blooms in late April with lavender pink flowers. Like most spring flowering shrubs the buds set themselves in the fall, but the PMJ is hardy to -35°. Another rhododendron which exhibits excellent cold hardiness is Koren Rhododendron a native of Korea, China and Japan. Unlike most rhododendrons it is deciduous, and blooms with magenta flowers before it leafs out in early May.
Northern Lights Azaleas is a series developed and released by the University of Minnesota and have flower bud hardiness from -30° to -45°. The shrubs in the series bloom mid to late May and offer a variety of colors.
- Pink Lights – light pink flowers with a sweet floral scent. The shrub can reach a height and spread of 8 ft.
- Rosy Lights – deep rosy pink flowers.
- White Lights – the buds are pale pink which open to white with a lightly yellow center. The shrub grows to 5 ft. tall and wide.
- Spicy Lights – salmon colored flowers with a slight fragrance. Hardy to -35° and the shrub reaches a height of 6 ft. with a spread of 8 ft.
- Orchid Lights – released in 1986. The flowers are light lavender in color but are sterile. The shrub is smaller at 3 ft. by 4 ft. but bud hardiness is to -45°.
- Golden Lights – also released in 1986 has golden yellow flowers and has the advantage of a greater resistance to mildew.
- Northern Hi Lights – is the latest release in the series. The flowers are creamy white with a bright yellow upper petal. The shrub grows to a height of 4 ft. with a spread of 4-5 ft.
Both azaleas and rhododendrons prefer acidic soils so they would benefit from the addition of peat or sulfur to the soil when they are planted, and fertilized once or twice each year with an acidic fertilizer. Azaleas thrive in full to partial sun. Rhododendrons tolerate more shade but their evergreen leaves need protection from sunscald in the winter. Both are sensitive to heat so avoid the southern or western sun,
Forsythia is a non-native spring flowering shrub that exhibits flower bud hardiness through zone 3B. Forsythia is a deciduous shrub that grows fast and blooms in spring with yellow flowers. They thrive in full sun, in all types of soil and suffer from no serious pests or stresses which make them a good choice in our area. Cultivars that do well in our zone are Meadowlark, New Hampshire Gold, Northern Gold and Northern Sun. Forsythia has two seasons of interest, flowering from late April to early May and exhibiting a yellow fall leaf color.
Another spring flowering shrub that offers two seasons of interest is American Cranberrybush. In the spring the shrub has a backdrop of medium to dark green foliage for the 2-4 inch white, lacey flower clusters from May through June. In the fall the foliage can exhibit red, yellow or purple with suspended fruits of red or orange which is attractive to birds and wildlife.
Perhaps you don’t have much blooming in your garden this spring but consider planting a spring flowering shrub this year to brighten your landscape next spring.