OBJECTIVES The student will be able to

OBJECTIVES The student will be able to… • Relate the major characteristics of the seasons in terms of plant growth. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

OBJECTIVES The student will be able to… • Explain the effects of frost, snow, sleet, hail, and frozen soil on plant growth. • Identify microclimates in his/her immediate area. • Locate area on the USDA Plant Hardiness Zone Map and the AHS Heat-Zone Map. • Recognize outside areas with full sun, partial sun, and full shade. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS • All parts of the U. S. (except Hawaii & Puerto Rico) & Canada are considered in the “temperate zone”. – With normal seasons: spring, summer, fall, and winter. • Seasons can be classified as “wet” & “dry” in some areas. • Some U. S. areas are “tropical” or “subtropical”. – They do not experience frosts and freezes. • Mainland tropical zones in California & Florida may have variations of 20 - 30 deg. F in daytime highs and nighttime lows throughout the year. – The true tropics lie between the tropics of Cancer and Capricorn, 23 deg. north & south of the equator. • With negligible temperature variation through the year. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS • California has a “Mediterranean climate”: – A wet winter season. – Short spring, starting in February. • Rain slowly tapers off. – Long summer/fall, until October. • Little or no rain falls for months. True also of the desert Southwest. Winter rains are followed by a short, spectacular flowering spring, then a long, hot, completely dry summer. Figure 4 -1 Desertification, enlargement of deserts due to climate change, will affect ability of existing plants to survive. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS • The growth patterns of plants vary widely from season to season depending on the plant type. – Some are spring bloomers, others don’t flower until fall. – Some begin to grow as soon as snow has left the ground. • Such as asparagus. – Others produce no growth until all chance of frost is past. • Such as lilies. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS Spring • For the majority of plants in temperate zones, spring is when the majority of yearly growth takes place. • This yearly growth flush includes: – – Leafing out of trees. Emerging and blooming of bulbs. Blooming and fruit setting in fruit trees. New shoot growth in shrubs and trees. • Some plants, such as grapes, make all new growth for the year during this 1 - or 2 -month period. – Others, such as lawn grasses, continue to produce new growth as long as the weather is favorable. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS Summer • Summer is a period of maturing in plants. – Some plants have their flowering period. • Tomatoes and corn. – Others, which flowered in the spring enlarge/ripen fruits. • Such as fruit trees. – New, tender spring leaves toughen to a leathery texture. • Many plants accumulate energy in the summer to enable them to live through the long winter. – During which it will have no leaves and be completely dependent on the food stored in its roots and branches. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS Fall • Fall is a transitional season for plants that live yearto-year & the end of life for those living one season. • Those surviving the winter engage mechanisms to will ensure their winter survival: – Dropping leaves & stopping new growth. • A nearly static state to await favorable growing conditions. • Plants that live one year must have produced seeds capable of sprouting in the next growing season. – And must have dispersed those seeds throughout the area by their own unique evolutionary means. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

CLIMATE AND SEASONS Winter • For most plants, winter is a time of waiting. – When temperatures are below freezing, water is solid and cannot travel readily throughout the roots and stems. • Lack of water & leaves drastically slows biochemical processes in the plant, putting most in a state of suspended animation. – Until the return of favorable growing conditions. • Except evergreen plants such as pines, spruces, firs, junipers. • It is advisable to water evergreens during periods of thaw when soil is able to take in moisture. – This can help avoid unsightly winter burn. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE • The elements combining to make up a climate include primarily: – Temperature; Precipitation; Humidity; Light; Wind. • Each has a wide range of variation and a dramatic effect on plant growth. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Temperature • Temperature, largely determines the geographic range over which a plant will grow. – Particularly minimum winter temperature. • The lowest temperature that a plant can withstand is called its cold hardiness or cold tolerance. • For many plants about 28 deg. F is the minimum because at this temperature the liquid contents of the plant cells freeze and the plant dies. – These plants are designated as frost-tender. • Includes many vegetables and flowers. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Temperature • Plants that are able to survive temperatures lower than freezing are called frost-hardy. – They vary widely in tolerance to subfreezing temperatures. • In some cases the woody portions or root system may be frost-hardy but not the flowers and leaves. • Some garden flowers die to the ground in fall but grow back from the roots the following spring. • Some houseplants and many tropical plants suffer chilling injury at temperatures less than 50 deg F. – This is why bananas turn black in the refrigerator. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Temperature • Minimum winter temperature limits areas where many plants can live. – For some plants lack of cold prevents survival. • Fruit trees such as apple & cherry; Flowers like peony & tulip. • For temperate-zone fruits, an adequate number of cold days per winter, the chilling requirement, is essential for normal growth and fruit production. – Such as apples and cherries. • Each type of & variety of fruit has its own specific requirement. • Each crop also needs a certain number of adequately warm days in order to mature. – The growing degree-day requirement. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Temperature • A baseline temperature below which very little growth occurs is established for each crop. – Subtracted from the average temperature for a given day. • These daily measurements can then be added and compared to an established standard for that crop to determine when the crop will mature. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Frost • Understanding frost types & weather conditions that favor each is important because of damage done to frost-tender plants. – A frost can be one of two types: Radiation and hoar frosts. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Frost • Radiation frost - occurs when the air is cool and calm and skies are clear. – Warmth from the sun accumulated by soil and plants in the day is lost at night as heat radiating upward. • If the day was warm and the night only slightly below freezing, heat in soil & plants may last all night and offer frost protection. – If not, frost damage will result. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Frost • When plants are covered by a barrier blocking flow of heat to the sky, frost can often be prevented. – Clouds form this barrier, and radiation frosts seldom occur on cloudy nights. – On clear, protection by layers of newspaper, cloth, smoke, or plastic film can serve the same function. • Sprinkler irrigation of plants is also used to prevent frost. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Frost • The second type of frost is caused by a cold air mass moving into an area. – Carrying off heat from the plants, which are then frosted. • Frost often leaves ice crystals on plants and the ground in the early morning, are called hoar frosts. – Called black frosts, because the first sign of their occurrence is the blackening of injured plants. • Appearance of frost in some areas, but not in others close by is due usually to elevation differences. – Cold air is heavier than warm air & flows down to the lowest area. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Frost • The northern parts of the U. S & almost all of Canada experience freezing of the ground during the winter. • In unseasonably cold years many plants may “freeze out” as a result of the temperature around the root zone being too cold for the plant to survive. • Freezing of the soil causes water contained in it to expand, and may cause frost heaving. – Soil pushes up around the roots of plants leaving cracks over the root area, exposing them to drying winter winds. • Gardeners frequently lay a thick layer mulch over root areas of plants they know to be borderline cold-hardy. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Precipitation • Precipitation can take many forms including rain, snow, hail, and sleet. – Rain is of greatest value to outdoor plants. • Lack of rainfall is a limiting factor to plant growth. – Particularly in the western U. S. , where irrigation is essential to grow plants. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Precipitation • Excessive rain or rain occurring out of season can be as detrimental to plants as lack of rainfall. – Excessive rain can kill plants adapted to dry areas. • Unseasonable rain near harvest can make strawberries watery-tasting, and split unpicked apples & grapes. • Frequent rains spread plant diseases by splashing microorganisms from one leaf to the next. – Triggering the growth of dormant disease organisms present on plants. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Precipitation • Snow cover plays an important role in plant survival in areas with cold winters. – Protects low-growing plants low-temperature damage due to the chill factor or drying injury due to sublimation of the frozen water from the plants. • In sublimation, frozen water turns directly into its gaseous state without ever melting. – The process used in the food preservation technique known as “freeze drying”. • Requires energy in the form of heat, taken from the plant. – Damage is caused by the water lost from internal parts of the plant, as well as from the surface. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Precipitation • Sleet, hail, and freezing rain can be very injurious to plant health. – Sleet & hail tear leaves & bruise or knock off fruits. – Freezing rain often causes branch breakage on trees. – Heavy snowfall can cause breakage due to its weight. Figure 4 -2 A rosebush shows effects of a heavy snow load & freezing rain. Courtesy Susan Brandt Graham. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Precipitation • Dew is most likely to occur when the air is warm and humid. – After sunset, air temperature drops, and the atmosphere is unable to contain the water it held during the daytime. • Water precipitates out, in the small droplets called dew. • Although its effect on most plants is not great, it can be a factor in the spread of diseases in turfgrass. – It is also an important water source for plants that absorb water readily through their leaves. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Humidity • Humidity may determine how well a plant will grow. – Defined as the amount of water the air contains relative to the amount it is capable of holding. • At that specific temperature. • Often higher humidity improves plant growth by reducing the rate at which plants lose water. – Low humidity will not seriously hinder growth of most outdoor plants if there is adequate water around the roots. • Indoors plant in cold-winter climates are commonly damaged by insufficient humidity. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Humidity • Fog and mist, can influence plant growth greatly. In coastal California climates, the moisture from fog and mist is absorbed by plants, supplementing meager rain. At the same time this vapor retards loss of water from leaves. Figure 4 -3 Fog in a redwood forest of coastal California. The moisture-laden air is the only source of water during the dry summer months. Photo by Rick Smith. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Light • Light duration, intensity, and quality affect growth of outdoor and indoor plants. – May control flowering and growth rate. • Light duration in any particular region depends on distance from the equator and season. – At the equator, day & night are equal length all year. • North or south of the equator, days become longer in the summer and shorter in winter. – The further from the equator, the greater the difference between the longest summer day and shortest winter day. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Light • The duration of daily light a plant receives is important, as it determines the period of time it can manufacture the carbohydrate necessary for growth. – Duration of the night also affects the start of some plant processes, such as flowering. • Light intensity or brightness affects photosynthesis because, in general, the brighter the light intensity, the more photosynthesis occurs. – Moderate to bright intensities are most beneficial. • Latitude will alter intensity. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Light • At the equator the sun passes overhead all year. – In the northern U. S. it is nearly overhead in summer. • Low in the southern sky in winter. • Winter intensity is lower because of the distance through the atmosphere the rays must travel. – Lesser amounts of light signals plants to become dormant. – For evergreens, lower light intensity of winter is sufficient to continue photosynthesis and sometimes growth. • Indoor plants can be seriously retarded by the decrease in light, as many are already growing at subsistence light levels. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Light • When buying plants for the garden, it is essential to know light preferences of plants being purchased. – One must know the approximate amount of light the area receives in order to choose a plant that will grow healthily. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Light • Areas around the home can be classified as: – Full shade - areas in which the sun rarely shines directly. • Northern sides of houses, narrow areas between houses. • Under large trees & other areas shaded almost all day. – Partial-shade - areas which receive direct sunlight for about one-third to one-half of the day. • East- and west-facing walls of houses • Under small/finely foliaged trees that admit “filtered sun”. – Full sun - found on the south sides of houses. • Or where there are no trees, shrubs, or structures to block light. • Full sun can also be on the west side of houses in the western U. S. , as the afternoon sun in these areas can be very strong. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ELEMENTS OF CLIMATE Wind • Wind is the fifth climatic element governing growth. – Ocean wind limits the number of plants that can be grown near the shoreline. • By salt spray, which browns plant leaves. • By the intensity, which whips and breaks leaves and branches. – Hot desert winds increase the rate of moisture loss from soil & plant leaves, intensifying drought conditions. – Subzero winds in cold northern areas damage evergreens by removing moisture from foliage, freeze-drying it. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE • Natural factors modifying climate include distance from the equator, elevation, terrain, and the nearby presence of large bodies of water. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE Elevation • Changes in elevation can give areas only a small distance apart completely different climates for plant growth. – The higher the elevation of an area, the colder the average year-round temperature • Every rise of 300 feet (91. 4 meters) causes an average temperature decrease of 1 deg. F. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE Terrain (Topography) • Changes in terrain alter climate, particularly rainfall. – Most rainstorms move from west to east in North America. – In a narrow range of hills, west-facing slopes often receive much more rainfall than east-facing slopes. • Heaviness of the water in rain clouds prevents them from passing over mountains until most of the precipitation has been released. – The drier region on the eastern slopes often is referred to as a rain shadow. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE Terrain (Topography) • Sloping terrains can vary in temperature by several degrees from the top of the slope to the valley. Cool air, heavier than warm air, will flow down a slope and collect at the bottom, a phenomenon called air drainage. Plants growing higher on the slope are less likely to be damaged by cold than those at the bottom. Figure 4 -4 Typical cold-air drainage on sloping land. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE Bodies of Water • Large bodies of water like the Great Lakes & oceans exert strong effects on the climate of nearby land. – The enormous volume of water absorbs heat in summer, making adjacent land cooler, and gives it off in the winter, raising the temperature. • On the North American continent, the influence of large bodies of water on agriculture is considerable. – Warmer winter temperatures along the Great Lakes make these regions large commercial growing areas for fruits such as grapes, cherries, and peaches. – Most of the Pacific coast is warm enough to grow certain vegetables all winter, but inland these crops would freeze. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

FACTORS MODIFYING CLIMATE Climate Modification by Humans • People can modify climate either intentionally or unintentionally. – Among the most widespread unintentional causes of climate change are air pollution and consequent smog. • Smog affects plant growth by temperature modification, acting like an insulation layer, preventing heat from escaping. • Particulates settle onto leaves & decrease light reaching plants. – Smog affects plant growth is through foliage injury by toxic gases entering leaves, causing them to partially brown and sometimes to die. • Plants classified as intolerant (many pines, for example) cannot be grown in smoggy areas. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES • Microclimates are small areas with slightly different climate characteristics than the surrounding land. – May be less windy, shadier, moister, warmer, or in any other way different from the typical climate. • These differences affect plants, sometimes helping and sometimes hindering growth. • Microclimates may be either artificial or natural. – They can be formed by the natural terrain & vegetation. • Or unintentionally created by structures, fences, roadways. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES • Although they often go unnoticed, they can be used by the observant gardener to provide the specialized growing conditions favored by different plants In some cases they make it possible to grow plants not normally considered cold-hardy in that area. Figure 4 -5 A microclimate for a fern would be under trees or against a north wall. Courtesy of B. J. Fundaro, Sonoma State University, Rohnent Park, Calif. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Outdoor Microclimates • A natural microclimate example is a frost pocket. – Colder, possibly moister due to water runoff. • Suitable for moisture-loving plants not easily damaged by cold. • Another natural microclimate is found under trees. – Shadier/cooler in summer, good for shade-loving plants. • Or growing indoor foliage plants outdoors in summer. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Outdoor Microclimates • Plants in the microclimate under the eaves of a house live under different environmental conditions than plants living away from the house. – Shielded from rainfall by an eave, so the soil will be drier. – The wall may afford protection from cold or drying winds – Radiates warmth from the heated dwelling. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Outdoor Microclimates • During cool periods, additional warmth speeds up or prolongs growth, but if a wall faces south it may be excessively hot in summer & damage can occur. Frequently the case with parking lot trees, which become overheated due to heat radiating from the asphalt. Figure 4 -6 Scorch on maple due to excess heat. Courtesy Dr. R. E. Partyka, Columbus, Oh. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Outdoor Microclimates • At night when temperatures drop, objects begin losing heat to the cooler night air. – Heat radiating from the ground and buildings can protect plants from frost & extend the growing season. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Outdoor Microclimates • Wind can be intensified or lessened in a microclimate. – A plant by a wall will generally receive wind protection unless it is directly in the path of prevailing winds. • When two walls are parallel, a wind tunnel can be formed, and wind conditions will be worse there than in a completely unprotected area. – Frequently formed between closely spaced buildings. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Indoor Microclimates • Indoor microclimates with varying temperature, light, and humidity are found in houses/apartments. – Upstairs rooms may be warmer than downstairs ones. – A basement may be up to 20 deg F cooler – The north side of the house may be cooler than the south. • Even within a single room, cool microclimates will be found adjacent to windows in cold-winter areas. – Because of cold entering through the glass. • Microclimates of varying humidity are also common. – In the kitchen and bath, evaporation raises the humidity. • A basement is also usually humid. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

MICROCLIMATES Indoor Microclimates • Light microclimates are easy to detect, being governed by the size and location of windows. – The farther from a window a plant is, the less light it will receive, and each foot/meter of distance can be thought of as a different microclimate. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ADAPTIVE STRATEGIES OF PLANTS FOR CLIMATE TOLERANCE • Plants have evolved adaptive strategies to cope with adverse environmental conditions. – The most common adaptation is winter dormancy. • Plants in desert areas develop the ability to store water in their leaves, making leaves fleshy & thick. – Cacti take this to an extreme in that they have no leaves. • Only a thickened stem that forms the bulbous body of the plant. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ADAPTIVE STRATEGIES OF PLANTS FOR CLIMATE TOLERANCE • Desert plants (xerophytes) can protect themselves from excessive sun. – A most interesting example is the “baby toes” plant. • Native to the Cape Province of South Africa. This small cone-shaped plant lives almost entirely underground with only a transparent “window” at the soil level through which light penetrates to the interior cells, for photosynthesis. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. Figure 4 -7 Baby toes (Fenestraria sp. ), a South African plant adapted to a very arid climate. Paloma Colomer Arroyo, Jaen, Spain. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ADAPTIVE STRATEGIES OF PLANTS FOR CLIMATE TOLERANCE • Water loss from leaves in less severely dry climates can be reduced in two ways… By a wax layer the plant excretes to cover its leaves. Or a thick covering of silvery hair that reflects sunlight and also insulates the leaf from air. Figure 4 -8 A closeup of the thick hair covering lamb’s ears, a garden plant originally native to Northern Turkey and Southern Iran where it grows on rocky hills. Courtesy of Mary Hanks. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

ADAPTIVE STRATEGIES OF PLANTS FOR CLIMATE TOLERANCE • At high elevations both cold temperature and drying winds become factors in plant survival. – The term tree line refers to the elevation at which trees can no longer grow due to climate extremes. • In growing conditions without much sun, leaves of plants are very large to expose the maximum amount of leaf area to the available sunlight. – Forest floor vegetation in tropical forests and the source of many of our best indoor plants for growing in limited light. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA • The question of where in the country a specific plant can be grown is important to every gardener. – There is little to worry in plants bought at local nurseries. • Nursery owners seldom sell plants that don’t grow in their area. – When consumers mail-order plants, they must ensure plants they have selected will grow in their area. • This valuable information is usually given in the written descriptions of the plant, found in gardening books from a library, or on the Internet. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA USDA Plant Hardiness Zones • The USDA has prepared maps showing zones of minimum winter temperatures in the U. S. & Canada. – After determining minimal plant survival temperature, one must determine minimum winter temperature of the area. • Eleven zones are outlined, ranging from completely frost-free areas in Florida, Texas, and California. – To a -50 deg F. or colder zone in Canada. • The map takes into account cold mountain climates in warmer zones, as shown in Colorado. – For the most part, it is made of bands that correlate minimum winter temperature & distance from the equator. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA USDA Plant Hardiness Zones • The USDA zone map is not the only plant hardiness map that exists, but it is the most widely used. – Some states with climates influenced by many factors have designed more detailed maps. • The University of California at Davis lists twenty-one separate climate zones, due to the influences of the Pacific Ocean and mountain ranges. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • The USDA Plant Hardiness Zone Map addresses plant hardiness in excessively hot temperatures. – Instead of excessively cold temperatures. • Knowledge of heat zones may be more important in the future, especially during drought periods. – Heat damage is less apparent than damage from cold. • Death of the plant due to heat generally is gradual. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • In addition to scorch, heat symptoms such as failure of flower buds to open, bleaching of leaves to a paler color, failure to grow at a normal rate, or failure to produce fruit may all occur. – Leaves may droop even though the plant is receiving regular watering. • Plants may also become more attractive to insects. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • The American Horticulture Society Heat-Zone Map divides the U. S. into twelve heat zones. – By the average number of days per year that the areas experience temperatures over 86 deg F. • The range is from 0 to 210 heat days per year. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • Heat tolerance rating of a plant in will soon be listed next to its USDA cold-hardiness number on care tags, in gardening references and in catalogs. • A plant will have two ranges. – For example: Lily 3– 8, 8– 1. • The first range (3– 8) will designate the USDA low-temperature hardiness by zone. – According to the lowest average temperature in winter. • The second (8– 1) will designate heat tolerance. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • If you live in USDA zone 7 & AHS heat zone 7, you know a lily will survive both the winter temperatures & hot summer temperatures of your area. • Not all plants have been coded by AHS heat zone. – Even when so coded, some plants may survive out of, or fail to thrive within, the zone area specified due to unseasonably warm or cool years. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

PLANT GROWING ZONES IN NORTH AMERICA American Horticultural Society Heat-Zone Map • Stresses that will independently & together alter the ability of a plant to grow within a specific heat zone: – Light deprivation and microclimates. – Soil characteristics & plant nutritional status • In all cases, the classification assumes that the plant is receiving adequate watering. Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458

END OF CHAPTER Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson Prentice Hall - Upper Saddle River, NJ 07458