Weather affects plants in many obvious ways, but also in ways we may not realize. While a tree snapped by a gust of wind is easy to associate with the event, large trees may not show the effects of drought until several years later. In addition to any direct effects, weather-related stress can make plants more susceptible to disease and in-sect problems.
Weather is whatever is happening now – precipitation, temperature, wind, sun, and humidity. It is not the same as climate, which is historical weather or the average of weather conditions over a long period of time. Climate determines what will probably grow well in your area, but plants can still be damaged or killed by extreme weather.
While we have no control over the weather, in some cases we can try to design and maintain the garden to minimize the negative effects of weather on our plants.
Factor to consider when growing plants in various weathers:
Generally, plants grow faster with increasing air temperatures up to a point. Extreme heat will slow growth and also increase moisture loss. The temperatures for optimal growth vary with the type of plant. Some annual flowers and vegetables are extreme-ly sensitive to cold, and transplants should not be planted until temperatures are con-sistently warm.
Extremely hot or cold soil temperatures can also hamper plant growth, as well as affect seed germination.
Cool temperatures in fall trigger the plant to reduce growth and store energy. As tem-peratures approach freezing, growth stops and the plant (if perennial) becomes dormant. Plants are better able to withstand cold temperatures when dormant. A sudden cold snap in late fall before the plant has had a chance to harden off can do more harm than sustained cold temperatures in mid-winter.
Plants can be classified according to their light needs, such as high, medium and low light requirements. The light intensity received by an indoor plant depends upon the nearness of the light source to the plant. Light intensity rapidly decreases as the distance from the light source increases. Window direction in a home or office affects the intensity of natural sunlight that plants receive. Southern exposures have the most intense light. Eastern and western exposures receive about 60 percent of the intensity of southern exposures, while northern exposures receive 20 percent of the intensity of a southern exposure. A southern exposure is the warmest, eastern and western are less warm, and a northern exposure is the coolest. Other factors such as curtains, trees outside the window, weather, season of the year, shade from other buildings and window cleanliness also effect light intensity. Reflective, light-colored surfaces inside a home or office tend to increase light intensity, while dark surfaces decrease light intensity.
Plants need water to survive. People are made up of approximately 70 percent water, but plants are closer to 90 percent water, and without water, plants become stressed and die. Even the desert cactus requires water, albeit much less water than other plants.
Water nourishes the plant and hydrates it. Water in the soil breaks down and dissolves minerals and critical elements in the soil. As the plant absorbs water through its roots, it also transport nutrients into its cells.
Water and humidity in the air can encourage plant growth, but too much water can kill plants. It’s important to provide your plants with the right amount of water for their needs.
Plants need 18 elements for normal growth. Carbon, hydrogen, and oxygen are found in air and water. Nitrogen, phosphorus, potassium, magnesium, calcium, and sulfur are found in the soil. The latter six elements are used in relatively large amounts by the plant and are called macronutrients. There are nine other elements that are used in much smaller amounts; these are called micronutrients or trace elements. The micronutrients, which are found in the soil are iron, zinc, molybdenum, nickel, manganese, boron, copper, cobalt, and chlorine. All 18 elements, both macronutrients and micronutrients are essential for plant growth.
Cold weather plants
Camellias can add color and interest to your garden all year long. Even in colder zones, you can probably cultivate some of the new cold climate hybrids.
The most well-known camellia is probably the tea plant (Camellia sinesis), but with so many species to choose from — up to 280 — there’s probably a variety to fit that perfect spot in your flowerbed.
ften popping up through a layer of snow long before the crocuses are out, snowdrops are welcome guests in the garden. One wonderful thing about this unassuming little plant is that it will survive even an extended snow event, waiting dormant for conditions to improve.
The small, white, bell-shaped flowers of the snowdrop are suspended from short, delicate stems, and although traditional varieties grow only to six inches or so (15 cm), newer hybrids can reach to up to 10 inches (25 cm).
Hot weather plants
Rose Moss (Portulaca grandiflora)
Rose moss is very tolerant of summer heat. It is a low growing, succulent plant that comes in an array of bright and intermediate shades of red, rose, pink, orange, white, and yellow. Comes in single or double flowered varieties. Grows to 6 inches (15 cm) tall and 1.5 feet (.45 m) wide. Flowers shaped like mini roses.
Dusty Miller (Senecio cineraria)
Dusty miller makes an attractive foliage plant that works well in the garden and its grey foliage makes it a good plant for bringing other plants together. Grown as annuals these plants have very decorative silver leaves that are finely divided. They come in many varieties.