Half-hardy perennials have to be something a bit special to be grown outside as garden flowers. To keep them through the winter, they must be dug up and kept safe inside, then planted out again in the following spring. They are more work and a lot more trouble to keep alive than hardy perennials. Consequently, they are mainly grown by enthusiasts, who not only take this extra work in their stride, but also have the luxury of a heated greenhouse in which to keep them.
Tender subjects such as heliotropes, lantanas and penstemons were at one time widely grown in parks and public gardens to create exotic and lavish bedding schemes. Now, with the rising cost of labor and heating, they are fast disappearing as common plants.
Even that popular mainstay of park bedding schemes, the geranium, is now mostly grown anew every year from freshly sown Fl hybrid seed rather than from cuttings taken from the old plants and kept through the winter. A classic example of half- hardy perennials being grown as half-hardy annuals. The specialized production of hybrid seeds has made this possible. It is no coincidence that three of the most popular hobby plants of the gardening enthusiast namely geraniums - the established named varieties grow, from cuttings, not those raise from seed - dahlias and chrysanthemums, are all half-hard perennials. Plants such as these keep green fingers occupied al the year round. The very fact that they thrive on constant car and attention, protecting, propagating, potting and planting, is just what enthusiasts are looking for.
There is no danger of these three particular hardy perennials disappearing from the garden scene. In fact, you should encourage their growing in every possible way, not least by sponsoring exhibitions and competitions at both local and national level.
Apart from the well-known rooted dahlias and begonias, the old plants of hardy perennials are rarely kept for replanting. In most cases, cuttings are taken either in late summer or autumn and grown on steadily inside during the winter. Alternatively, as with chrysanthemums, cuttings are taken in the spring from roots that have been protected through the bad weather. These, with their entirely new set of roots, make new young plants with better flowering potential than would be possible from old plants. In fact, old plants of certain subjects are not good movers, and taking cuttings is the best way of keeping them for another year.
