Primetime Newspapers
By Calvin R. Finch, PhD,
SAWS Water Resources Director, and Horticulturist
Week of May 22, 2006
 “Here are Three Summer Blooms to Consider for your Landscape –Vincas, Lantanas, and Wax Leaf Begonias”    

Vincas (also called periwinkle) used to be the favorite annual flower in the United States.  The flower blooms constantly until cold weather arrives, is generally deer-proof, qualifies as a xeriscape plant, and is not bothered by insects.  Its popularity has been reduced, however, because it is very susceptible to a fungus disease – aerial phytophera.  The disease attacks the foliage and stems with the result that they melt to mush.

 

Vincas are still a good choice for summer color if you take some precautions to prevent aerial phytophera.

 

·      Aerial phytophera is a fungus that requires moisture on the foliage to infect the plants.  Wait until the humidity is relatively low to plant them.  Mid-May is usually a good time.

  ·      Vincas do best when they are watered infrequently.  Once every two weeks after they are established is plenty.

 

·      Water with drip irrigation or by flooding the soil.  Sprinkling overhead results in infected plants. 

 

·      Mulch the vinca bed to reduce the need for watering.  The mulch also reduces splash from the soil.  The disease organisms are in the soil.

 Vincas are available in several sizes and color variations.  Lavender, white, and near reds are available.  There are many bicolors in the three colors.  Plant vinca in full sun.

 

Lantana is another blooming plant to consider for hot weather.  All varieties are perennials that usually die back to the ground in the winter.  Lantanas are desirable because they are good xeriscape plants, are not usually eaten by deer, and have good resistance to disease and insects.  The blooms are usually cyclical, in that they bloom for six weeks, rest for six weeks, and then bloom again.  Area landscapers have speeded up reblooming by deadheading the planting every three or four weeks.  A light (.5 inches deep) pruning with the string mower stimulates the new flush of flowers.

 

There is one insect that reduces lantana blooms some years, the lace bug.  The little beetles suck the juices from the plants just like spider mites, scale or aphids.  The symptom is the same as well; the foliage becomes dusty or milky looking.  The plants recover, but a spray of acephate at first sign of a symptom will eliminate the problem.  Organic gardeners can try neem oil to control lace bugs. 

 There are many choices of size and growth habit among lantanas.  The most popular are the spreading lantanas such as “New Gold.”  One “New Gold” plant in good soil will cover four feet in every direction.  It dies back to the roots every winter.

 

Lantana montevidensis, a spreading lantana that is not as aggressive as “New Gold.” It is also not as sensitive to cold and shade.  The plant blooms best in the spring and autumn, and some winters it will bloom until there is a hard freeze, even if it is growing in partial shade.  The white version does not bloom as heavily as the lavender version, but both make good container plants to attract butterflies and hummingbirds.

 

There are a number of small, clump lantanas.  There is a variegated selection with lemon-yellow blooms called “Samantha” and an off-white plant called “Popcorn.”  Check and see what your nurseryman has to offer, every year there are new offerings. 

 

In the large bush, consider Irene (pink and yellow), Radiance (red, orange, and yellow), Dallas Red (red and yellow), and Confetti (pastel pinkand yellow). 

 

Now that cyclamen and primulas have declined, area gardeners are looking for a shade blooming plant that can survive the heat.  The usual choices are wax begonias and impatiens.  Begonias have certain advantages over impatiens.  They have much more drought tolerance and cold tolerance.  A begonia turns off-color when it is under watered, but it is not as quick to decline in a drought as impatiens.  Some years, impatiens die from the heat even when they are watered every day or two.  Begonias usually perform well in the shade with twice weekly waterings.  In addition to heat tolerance, begonias planted now may survive the winter.  It takes a serious hard freeze to kill begonias.