With each year's winter setting new records for extreme temperatures and unusually late cold snaps, many farmers who have never previously considered frost protection are exploring their options.
Spraying your plants with a steady stream of overhead water is a well-tested and proven way to prevent frost damage. Even though encasing sensitive plants in a layer of ice may seem like the last thing you want to do, it's an efficient alternative to costly and wasteful heaters.
Learn five important facts about using irrigation to prevent a cold snap from ruining sensitive fruit trees and other important crops.
1. Wetting the Soil
Wetting leaves, buds, apical tips, and other above-ground parts of a plant are usually the primary focus of winter irrigation for frost damage control. However, soaking the soil thoroughly is also essential to protecting plants and maintaining a warmer ambient temperature in each field.
This step is essential because dry soil is full of air pockets, which are inefficient as insulation. Wetting the soil until it's holding the right amount of moisture closes these gaps to keep the soil warmer even if it freezes. Wet soils are also darker, allowing the ground to absorb heat faster when the sun rises again after a frost.
2. Checking Air Humidity
Picking the perfect time to apply water prevents moisture waste and allows you to catch the plants before frost damage sets in. Yet protecting your plants isn’t as simple as starting up sprinklers every time the temperatures near the freezing point outdoors.
You need to know the wet bulb temperature, which is determined based on the dew point and relative air humidity. Consistently calculating this number on your own is tricky, so find a frost irrigation chart calibrated for your growing region's average temperatures and dew points.
Use a reliable weather-reporting source to check both the projected dew point and the temperature so you can find the right time to switch on sprinklers for maximum effect.
3. Freezing Heat
Many farmers are afraid to try irrigation for frost control after seeing the large ice formations that appear on trees, shrubs, and even hardy crop plants exposed in the fields. A coating of ice on delicate leaf and flower buds can be intimidating indeed.
But when water freezes, the phase change from liquid to solid generates a surprising amount of heat. After a thin shell of ice encases the plant material, that heat is trapped inside to ensure the plant material doesn't actually freeze. This is enough to prevent damage in a surprising range of plants.
4. Using Cover
Are your crops already covered with plastic or agricultural fabric to keep snow off and add insulation? You can still benefit from applying water because the heat released during ice formation travels through the covering and warms up the plants below.
Make sure your row covers or floating hoop covers can handle the weight of extra water and ice before setting up irrigation equipment. You don't want to collapse your covers if they're only suspended over delicate and small transplants with no extra support from hoops or frames.
5. Tracking Bud Development
Finally, irrigation for frost prevention is not always the right technique. It can still damage buds very close to flowering, leaves that are freshly emerged, and newly formed fruit. If the frost is very late in the spring or early in the fall, heaters and wind generators may be necessary. Check representative plants daily to determine what method to use to have the best chance at preventing frost damage.
We have everything you need here at Waterford Irrigation to set up any size of irrigation system to prevent frost damage this winter and spring. Call us at your earliest convenience.