Climate

Climate is the year round weather in an area Climactic variables –First and last frost dates –Average winter and summer temperatures –Precipitation and when it occurs –Snow depth –Wind and storm patterns –Lake effect –Hours of sun vs. cloud cover

Macroclimate describes the climate over a large area such as the north central US –Largely determined by latitude Temperature –Department of Agriculture Zone Map Growing zones described by winter temps and growing season Heat Zone Map

Hardiness Zones

Zone changes in 16 years

Excessively high temps can cause the plant to stop growing. This varies between species but generally occurs by 96F. 539cal/gm to turn water to water vapor. Leaves have evaporative cooling (evapotranspiration) In Duluth, we have Lake Superior!

Microclimate describes the climate in your yard or garden Slope Buildings

HOW TO PREVENT COLD DAMAGE Hardening off: (spring) get greenhouse grown plants used to the outdoor temps gradually. 80Cal/gm are given up to change 1 gm water to ice, so you can use water as frost protection covering Season extenders (fall), plant covers, mulches, leaves, leaf bags, straw etc Put plants in the ground at the right time ( soil temp) cool season vs. warm season plants

Five environmental factors essential for plant growth Light temperature Water Air nutrients

Light quantity Quantity –refers to the intensity or concentration of sunlight –Measured in foot candle, lux, lumen, watts –“full sun” 8 hours of unshaded sunlight during the growing season

Light Quality Wavelength that hits the plant surface Red and blue light have the greatest effect on plant growth

Light Duration The amount of time the plant is exposed to light during a day, plants are classified in 3 categories by their flowering response –Short day plants flower when the days are shorter than 12 hours ( long nights)– ( fall asters) –Long day plants flower when the days are more than 12 hours ( short nights) –Day-neutral flower in long day or short ( ever bearing strawberries)

Temperature Horticultural plants can be defined as warm-season or cool-season crops Temperature interacts with light duration. For growth to occur, photosynthesis must be greater than respiration

Water

Plants must have water available for growth to happen Growth can happengrowth delayedpermanent wilt point

Air Plants use CO2 in photosynthesis Plants use O2 in cellular respiration Air movement can increase or decrease transpiration and can shape plants Air quality is important – plant leaves can be damaged by air polution

Nutrients 16 essential nutrients are supplied through air and soil.