Climate

Climate is the year round weatherin 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 factorsessential 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 happen growth delayed permanent 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.