Penstemon is a very large family of both hardy and half-hardy plants. We are concerned now with those which are reasonably hardy and which producesuitable for .
Penstemon heterophyllus grows from 12 to 18 in. high, and from June until August freely produces brilliant blue tubular. P. barbatu,s has grey-green and spikes of pinkish-red blooms.
P. newberryi rupicola is a rather prostrate-growing plant, being covered with showy carmine-red flowers from July until September.
Some years ago a hybrid distributed under the name of ‘Six Hills’ made its appearance; this has pinkish-flowers on 6-in, from June to September. One of the good qualities of P. rupicola or davidsonii is its ability to withstand hot, dry conditions, and this is why it is so useful for the upper parts of a rock garden. P. scouleri is a shrubby, evergreen plant, with f a-in, of purple-mauve flowers from May to July. There are others of these more or less hardy penstemons, including the somewhat shrubby-growing isophyllus varieties, which are serviceable and gay during the summer, but those mentioned are at least an indication of what is available.
All are of easy. Very young growths secured in the late summer and struck in sandy soil under a frame or hand light will well, and sturdy plants can soon be secured. This glass protection should be retained through the winter, for such action not only encourages to develop, but also prevents frost damage and provides the necessary protection while the plants are becoming established.