Plants flowering beginning in May and continue blooming into June and sometimes beyond provide landscapes with mid-to-late spring colour. There are many such perennials and annuals. Broadleaved evergreens, trees, vines and deciduous shrubs capable of flowering in May and June are not as plentiful, but many choices exist.
Ninebark is a deciduous shrub blooming during May and June. Among its ornamental features in addition to its clusters of pink-white flowers is a peeling bark of different shades of brown. Arrowwood viburnum, a deciduous shrub with many stems, grows to 10 feet high and blooms during May and June, generating white flowers in sun or shade. New Jersey tea grows small enough at 3 feet high to serve as a groundcover on rocky slopes. It flowers from May through July. The shrub rose has a May to June blooming period growing to 8 feet and coming in many cultivars, such as Sun Runner.
Vines with flowers during both May and June include blue jasmine, a species from the Southeast requiring damp conditions. Blue jasmine flowers are pale blue or violet with white interiors. Supple-Jack is a woody vine fit for native plant gardens that blooms during May and June. It produces yellow-green flowers and sometimes attains 60 feet in length. American wisteria finishes flowering before June, but Chinese wisteria has flowers from May through the beginning of summer. It is a vine with potential weight requiring very strong support. Star jasmine from Asia flowers best in full sun. It grows to 6 feet and works as groundcover or on a trellis.
In U.S. Department of Agriculture Plant Hardiness Zones 10 and 11, Arabian coffee is an evergreen shrub or small-sized tree capable of flowering in May and June. It has fragrant flowers shaped like stars and can grow inside as a container plant protected from cold. Used as a foundation plant, hedge or in shrub borders, inkberry is another broadleaved evergreen plant for May and June blooming. Its white-green flowers change into dark berries on the female plants. Michelia from Japan has no tolerance for cold but grows as an indoor plant in sunny rooms, producing whitish-yellow flowers similar to tulips. The two lower petals on the creeping saxifrage flower are much larger than the three or four upper petals. This broadleaved evergreen grows to 18 inches in USDA zones 6 through 9.
Chinese fringe tree blooms in late spring/early summer with white flower clusters, making this a highly ornamental species. Hanging clusters of flowers, called racemes, are a May to June feature of the honey locust, as are the long beanlike seedpods they yield. These pods, up to 18 inches long, stay on the honey locust into winter. The tulip poplar has flowers and leaves giving it its name. The flowers have the same form as tulips and the foliage has a silhouette like a tulip. This is a potentially huge tree with some growing to 150 feet. Place it in open landscapes.