The Value of a Plant's Character

What characteristics do you look for in the plants you choose? Do you prefer a particular size and shape, a certain flower color, or productivity in food plants? As mentioned before, only the plants that suit your taste as well as your site, belong in your garden. But once you have decided your preferences for the more obvious qualities, consider some characteristics that will really save you money in the long-run.

Disease Resistance
Two rose bushes are next to each other in a border garden. One is practically defoliated, with the remaining leaves covered in black blotches. The other has full leaves and boasts blooms to boot. What makes the difference? Some plants are just naturally more resistant to disease than others are, and we don't always know why. Perhaps the cuticle, the waxy coating, on the leaves of the healthy rose bush is thicker, less acidic, or tougher than that of the sick rose bush. Physical and chemical attributes account for much of the mystique of natural resistance. We may not know exactly whysome plants resist illness, but we know disease resistance exists. Unfortunately, resistance often varies with climate or locale. Still, resistant varieties help you save money fighting plant diseases or replacing lost plants. Look for varieties that are resistant to diseases that are particularly prevalent in your area. Don't assume that just because you bought certified disease-free plants or resistant varieties, your plants will never get sick. The rest is up to you. Just as you can keep susceptible plants healthy with proper care, disease-resistant plants can get sick if not maintained properly.

Drought Resistance
Plants that evolved in arid places had to adapt in order to survive. Thin leaves, a glossy coating, fuzzy stems, or fleshy plant parts all help prevent water loss. Cacti are the classic example of drought resistance. But other plants also tolerate a lack of water. Remember that newly transplanted specimens usually will need to be kept moist until they adapt to their new surroundings.

Cold Hardiness
Frost damage can affect plants in many ways. Spring frosts may kill flowering buds, ruining a flowering or fruiting season, but causing little or no permanent damage. Severe winter cold may split branches or stems, which can kill the plant.
Gardeners who live in cold climate areas, including high elevations or northern latitudes, learn quickly to rely on short-season, late-blooming, and cold-hardy plants. If you garden in such an area, look for these designations when choosing varieties. Plants that evolved in cold climates developed some clever tricks for foiling frost. Short-season varieties take less time to flower or fruit than others of their type. They don't really tolerate cold, they avoid it. Late bloomers don't break bud in the spring until after hard frosts, hopefully. And cold-hardy perennials, shrubs, and trees have a unique method of surviving winter's chill, called super-cooling.
Cool temperatures alone don't cause winter damage. Dehydrating winds, bright sun, and temperature fluctuations all contribute to damage. Water retained in cells, freezing and swelling, and thawing and refreezing causes structural damage to plants. Cells burst and irreparably damage tissues.

Sun and Heat Tolerance
Severe cold as well as unrelenting heat, can damage plant tissues. With too much sun and heat, blossoms fade and fall, leaves drop, and fruit fails to develop. Even if plants are well-watered, the rate of transpiration (see Chapter 1) often outpaces the ability of the roots to absorb and replace lost moisture. But some plants have found ways to beat the heat.