13 July 2008

Beat The Heat In Your Garden

Obviously hot weather has adverse effects on plants, but what about the adverse effects on gardeners? Is human heat stress not of equal or greater importance? To understand how to reduce or minimize heat stress or heat-related illnesses, one must first understand what causes heat stress and when it is most likely to occur. Heat stress occurs when the body is unable to get rid of excess body heat by its normal exhaust methods - either from sweat evaporation, or from increased blood circulation to the skin surface where body heat can escape through radiation.

Environmental Conditions and Individual Factors - The four major environmental conditions that affect heat stress are air temperature, humidity, wind velocity, and radiant heat. Combine these with individual factors such as age, gender, weight, physical and medical conditions, and a person's degree of heat acclimation, and you can begin to predict how well a person might hold up in a hot, humid, still environment.

Heat-related illnesses - The majority of heat-related illnesses - early heat illness or fainting, heat cramps, heat rash, and heat exhaustion - are considered minor. Just because these illnesses are considered minor doesn't mean that they aren't important to recognize, and to try to avoid or minimize. For ill or frail individuals these illnesses may require medical attention.


The one heat-related illness considered major is heat stroke. Someone suffering from heat stroke can be in a life-or-death situation to which the first response should always be a 911-phone call.

The following are just some of the signs, symptoms, causes and treatments of these illnesses - consult medical references for additional information:

Early heat illness or fainting - Signs and symptoms - dizziness, fatigue and irritability; difficulty concentrating or making decisions. Cause - reduced blood flow to brain. Treatments - drink water; loosen clothes; rest in shade.

Heat cramps - Signs and symptoms - painful arm, leg or stomach muscle spasms; thirst and heavy sweating; (may not occur until after gardening activities). Cause - body salt loss due to sweating. Treatments - drink water, and avoid drinks with alcohol or caffeine; remove hat and loosen clothes; rest; lightly stretch muscles in a cool location.

Heat rash ("prickly heat") - Signs and symptoms - pricking sensation and tiny, blister-like red skin spots usually on body areas covered by clothes. Cause - plugged and inflamed sweat glands. Treatments - wear loose clothes; wash skin; apply talcum powder.

Heat exhaustion - Signs and symptoms - early heat illness signs, plus: loss of coordination; collapse; heavy sweating; cool, moist, pale skin; dry mouth with excessive thirst; fast pulse; low to normal temperature. Causes - reduced blood circulation and flow to brain; dehydration. Treatments - if conscious, give cool water to drink (do NOT give beverages containing caffeine or alcohol)-- make sure they drink slowly by giving a half glass of cool water every 15 minutes; rest lying down in a cooler, shaded area; loosen or remove clothing and hat; splash cold water on body and massage arms and legs.

Heat stroke - (May occur suddenly and is life-threatening. According to the American Red Cross. Follow the following recommendation.) Signs and symptoms - dizziness, confusion, headaches, irrational behavior, coma; reduced or no sweating; fast pulse; rapid breathing; convulsions, nausea, vomiting. Causes - dehydration; sustained exertion; reduced blood flow to brain, heart, etc.; body unable to cool itself; overexposure to high temperatures even without exertion. Treatments - call 911; move to shaded area; remove shoes and outer clothing, wrap in wet cloth/pour water on/fan rapidly; elevate legs; clear vomit to prevent choking; if victim refuses water, is vomiting, or there are changes in level of consciousness, do not give anything to eat or drink.

Heat stress solutions - How should gardeners avoid becoming a safety threat to themselves and others when it's hot? Start by evaluating potential risk of heat stress relative to the individual factors listed above. Someone who is older, overweight, in poor physical condition, taking allergy medication, or not used to being out in the heat is at far greater risk than someone who is young, trim, on a regular exercise program, and used to the heat.

Become a weather watcher. Set up a small weather station (with a high/low thermometer, rain gauge, etc.) to monitor not only the temperature, rainfall, etc., relative to plant growth, but also relative to personal safety. Watch or listen to the weather forecast each morning and noon to know in advance when stressful environmental conditions may occur. Plan activities for cooler time of day or season.

Evaluate work tasks and the time of day during which they must or can be done. Tasks that occur outdoors in sunny areas should be done in early morning or late afternoon whenever possible, not during the midday heat. Most watering, pruning, dead heading, etc., is better for plants when done in early morning. Many chemicals, especially insecticides, are better applied late in the day when the wind is down and beneficial insects are not present. Also, many chemicals volatilize quickly in the heat, losing their effectiveness and possibly causing harmful reactions to the applicator.

Allow yourself to acclimate to the heat slowly. Over a period of a week or two, gradually increase the amount of time spent in hot, still areas or in direct sun. Don't save hours of hoeing weeds from garden beds for the first day it goes over 90°F. Avoid working on surfaces such as asphalt, or near items such as metal, that may become very hot.

Be sure to stay hydrated, drinking as many liquids as possible. Don't wait until you are thirsty to have a drink, as thirst is an indicator that your body is already dehydrated. Water is preferred, except when heat cramps occur (then drink a lightly salted beverage like a sports drink). The water's temperature should be cool, not cold. Flavored beverages, such as fruit juices, iced tea and lemonade, as long as their sugar and salt content is low, are good water substitutes if they encourage large quantity consumption.

Perhaps one of the easiest ways to reduce heat stress is to dress appropriately. Though tempting, do not work in the yard in a tank top or without a shirt due to the potential for sunburn and skin cancer. Wear loose fitting, light colored clothes. Keep the fabric content high in cotton to aid sweat evaporation. Neckbands, headbands, wristbands, visors, and hats can increase evaporation to keep the body cool.

Lastly, take frequent breaks to reduce the amount of time spent in the sun or heat. After working for an hour, take a break to cool down and have a drink in the shade to reduce the build up of heat stress on your body.

Gardening Jobs For July:
You can sow a fall crop of bush beans now. Plant seeds two inches deep to protect them from the hot Sun. You can sow other vegetable seeds for an autumn yield, too, by planting them just a little deeper than you did in the spring. The best time to plant is after a rain shower.

If your celery is dong well, tie the stalks together to keep them from sprawling.

If you missed your peas’ peak period, you can still pick, dry and shell them for use in winter soups.

Don’t water your melons at the base of the stems. Doing so can cause rot. Build up a little earth around the stems to keep water away.

Once melon vines have set three or four fruits, remove any new blossoms. The remaining fruits will benefit from this, and you will still have plenty.

1 comment:

Anonymous said...

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Joan Stepsen
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