The following is information on Gaura lindheimeri, a good herbaceous perennial for Delaware landscapes.
Gaura lindheimeri, whirling butterflies, is an herbaceous perennial native to Texas and Lousiana that comes into its own in the late summer and throughout the fall. It is very drought and heat tolerant and can stand up against high humidity without diseases slaying it. It grows in an upright bushy form to a height of 2 - 3 feet and will flower continuously from spring till the first hard frost. G. lindheimeri prefers a moist rich soil with a neutral to alkaline pH, but it grows very well in most soils regardless of moisture or pH. Despite its heat tolerance, G. lindheimeri can thrive from zone 5 - 10 as long as the roots are well mulched for the winter. The flowers are small and white or pink depending on the cultivar, but as the white flower matures it becomes a pale pink. They are arranged on the stem like a gladiola, with a few flowers blooming at a time and are held above the foliage. After flowering, the spent flowers fall cleanly without dead heading. The flower stalks are thin and wiry, often tinged with red or pink depending on the coolness of the night temperatures. G. lindheimeri can be used as a background plant or as a wild flower planting; it doesn’t conform to a formal planting. Some of the newer cultivars are more compact like ‘Swirling Butterflies’ or a darker pink like ‘Siskiyou Pink’, Pretty in Pink’ and ‘Crimson Butterflies’. Pests include aphids, leaf galls, leaf spots, root rot and rust.
Information from Ginny Rosenkranz, University of Maryland in the October 23, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers, University of Maryland Cooperative Extension http://www.ipmnet.umd.edu/09Oct23L.pdf