University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article

SUMMER COLOR FROM TREES AND SHRUBS

Dr. Leonard Perry, Extension Professor
University of Vermont
 

When we think of color in the landscape, we usually think of flowers.  Shrubs and trees, however, form the backbone of most good gardens and there are some with attractive summer flowers.

One of my favorite small trees is the tree lilac (Syringa reticulata).  Related to the commonly known spring shrub lilacs, it is a bit different.  The tree lilac has a single trunk, glossy and attractive in itself.  It grows about 15 feet tall, with large dark green leaves, and panicles of attractive white flowers in late June or early July.

For other white-flowering trees, but much larger ones, consider the American yellow-wood (Cladrastis kentukea, formerly lutea) and the Chinese scholar-tree (Sophora japonica).  These do well in the warmer areas of our northern climate, but aren't hardy in the coldest areas.  The yellow-wood is one of my favorite large trees, having smooth gray bark similar to the beech.  Its clusters of pea-like white flowers hang down in June.
 
A group of trees that is hardy in most areas are the Basswoods or Lindens (Tilia).  The two most seen are the American with its large leaves (americana) and the Littleleaf with its smaller leaves (cordata).  The flowers are moderately attractive, fragrant, and quite attractive to bees.  You'll probably smell the flowers before you see them.

For shrubs that reach under three feet high, consider the Kalm St. Johnswort (Hypericum kalmianum) or the shrubby cinquefoils (Potentilla fruticosa).  The St. Johnswort has yellow flowers, and most cinquefoils do as well although some cultivars have white, peach, or other colored flowers.  The cinquefoil species is native in Vermont, and has become weedy in some pastures.  Usually found now in garden stores are the cultivars.

Perhaps the most common shrub seen in landscapes, particularly older ones, is the Peegee Hydrangea (Hydrangea paniculata 'Grandiflora').  Although an upright shrub, it is often trained into a tree shape, and so called the tree hydrangea.  The large white flower clusters last a long time in late summer, eventually turning pink then brown.  Even the brown clusters are attractive in winter, and sometimes used in dried flower arrangements.  There are many other selections of hydrangeas you may try, just make sure they are hardy for your zone.

An old-fashioned shrub deserving of wider use in gardens is the Sweet Mockorange (Philadelphus).  It is upright, with leggy branches, and is mainly grown for its fragrant, white flowers in June.  Once again there are several cultivars you may find.

Spireas are another group of old-fashioned shrubs, but more often seen in landscapes with their early summer flowers.  There are many cultivars to choose from the lower Bumalda and Japanese species, under 3 feet, often with pink or red flowers.  These are effective in masses, or scattered through fronts of borders, or in foundation plantings along homes.

Most common is the taller Vanhouette spirea with its arching branches to six feet tall, covered with white flowers in early summer.  It makes an attractive hedge.

Of course there are the roses.  This is one of the largest and oldest cultivated groups of flowering plants.  It makes sense then that there are thousands of cultivars in hundreds of species to choose from.  Many of the newer hybrids, especially tea roses, are not hardy in the coldest areas.  Shrub and old-fashioned roses may be hardy, but may only bloom in early summer.  Trials and results from Vermont can be found on the web (pss.uvm.edu/ppp/roses2004.htm).

More plants and their details can be found in the excellent revised edition of Landscape Plants for Vermont, edited by Drs. Norman Pellett and Mark Starrett.  It can be obtained from the Vermont Master Gardener program (master.gardener@uvm.edu).


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