Brian McGowan - Saving Container Plants: Overwintering Techniques for Keeping Tender Plants Alive Year after Year

Tender perennials are an amazingly adaptable and diverse group of plants.

Because theyve arrived in our gardens from so many different corners of the world, tenders introduce wonderful complexities and variations of texture, bold color, and sheer drama. Caring for them is surprisingly simple when you consider all that they offer the gardener. The diversity of tender perennials lends them to a marvelous variety of uses these are plants that range from delicate twiners to those that make bold statements, exceeding 10 or 12 feet in height. We suggest that you use your imagination and take your cues from the plants themselves.

Put simply, a tender perennial is a plant that, though hardy in its original habitat, will not survive the winter outdoors in the climate of the gardener. Tender perennials in one zone may be perfectly hardy in a different location. But for gardeners in any location other than a truly tropical one, chances are that some plants are tender perennials.

Some tender perennials are, in fact, tropical. But many others come from relatively moderate climates where winters just dont get as cold or, perhaps, as wet as they do where you live. From the temperate climates of the Mediterranean come marvelous gray-leaved plants like helichrysum and santolina that require dryness in winter. From New Zealand there are trees and shrubs, even grasses and sedges like Carex comans, that make delightful indoor plants. Both South Africa and the South American continent have wonderful plants that simply wont survive outside year-round in other locales, but which (we think youll agree) can enrich your gardening experience tremendously.

Will tropical and semitropical plants look out of place in your garden? Weve spoken with gardeners who worried that this might be the case. We suggest you experiment you might be surprised. After all, the geographic origins of most hardy perennials are already quite diverse. In our experience, the visual characteristics of plants their form, texture, and color are far more important in creating a visually unified and satisfying garden picture.

The word tender suggests that these plants will not survive frost. But many tender perennials tolerate light or sometimes even heavy frosts. They are called tender in a particular place simply because they are unlikely to survive an entire winter in that climate. This distinction may be confusing, but it really neednt be. Even hardy plants respond to freezing temperatures in different ways. Any plants tolerance of frost and cold is influenced by a variety of factors: hydration, stress, and the plants recent history. In general, only plants that originate where frost is a common occurrence will withstand it consistently, and even this is not always the case.

Most gardeners have noticed that the ubiquitous hosta, though reliable and quite hardy in a Zone 5 garden, is prone to react extremely to late-spring frosts. In years when these occur, hostas will generally grow an entirely new set of leaves to replace those that succumbed. Although a plants appearance may be affected for the duration of the season, this doesnt mean that its not hardy. Its just an indication of the structure of hosta leaves and stems, and shows that once theyve begun to grow, hostas are sensitive to frost, despite being hardy to much colder temperatures while in a dormant state. Its also an indication that in their Japanese homeland, frosts rarely occur once the plants have leafed out.

Other plants seem unaffected by cold nights. Some salvias, for instance, will continue as before, generally blooming and carrying on as if nothing has happened. This is a reminder that frost does occur in the desert, where salvias originate, and also that although most tender salvias cannot survive the winter in many colder zones, they are well adapted to life in the spring, summer, and fall in those places.