|
|
|
 Avoiding Frost Damage
In Corona, Riverside County, California during winters prior to 2007 we recorded as many as three nights in a row of 27° F with no frost damage to any of our plumeria. Why is that? The following is some incite as to what a plumeria grower needs to be aware of and what some precautionary actions are.
Commercial growers can protect their crops by wind machines orchard heaters and row covers while they may be impractical for the home plumeria grower. So you may ask “just what should I do?” The following is a summery of practices that we do at “Kimis Plumeria”.
First and foremost the Plumeria Grower needs strong pre-conditioned plants to withstand the frosts and cold prior to winter. To toughen plant tissues in the fall, do not apply nitrogen fertilizer after the first of September. Any fertilizer application should be high in potassium (K), as this element is known to promote thick cell walls. We have found Pro-TeKt by Dyna Grow and Liquinox Co.’s 0-10-10 are two products containing potassium that work well for us. Another nutritional technique is to spray all plant surfaces with kelp solution. Cytokinins present in the seaweed toughen the plant cell walls. Another useful precaution is to apply anti-transpiring sprays. All the plant surfaces are sprayed prior to anticipated frost, and the protection afforded is suggested to be from two to eight degrees (°F). One product we recommend is “Cloud Cover”.
Another approach to increasing the low-temperature tolerance of plants is by eliminating dust and ice-nucleating bacteria (INB) from all plant surfaces. Recent research has demonstrated that both dust and these bacteria (INB) contribute to frost or freeze damage. Some plants, which usually succumb at 30° F can be super cooled to 24° F without damage if these bacteria and dust are eliminated from the plant’s surfaces. Dust and bacteria promote the formation of ice crystals that pierce plant cell walls, leading to desiccation and death. So thoroughly wash your plumeria with a non damaging water spray. While not a completely accepted method, these bacteria (INB) can be killed by spraying plant surfaces with a bactericide or Hydrogen Peroxide (H202). We suggest Hydrogen Peroxide (H202) mix @ 12 oz. 3% H202 to one gal. water with non-ionic surfactant i.e. Coco Wet. Use fine mist spray, cover ALL plant surfaces.
Important to realize is a dry “stressed” plant is more vulnerable to frost than a plant that has been recently watered. This includes deciduous or dormant plants of any kind.
On a cold night with air temperatures in the low thirties or into the high twenties, the earth’s surface at 52° F is like a giant heater. You may have noticed that plants placed under the leaf canopy of a large tree or building overhang escape serious freeze damage, while those out in the open are often killed. These covers contain the earth’s heat.
Plumeria growers are alarmed when winter comes and frost is predicted. Radiation frosts occur when clear calm conditions during the night allow the ground to cool by radiation to the sky. Warmth from the soil travels upward into the air raising the air temperature.
Why not mulch to protect your plants? Lawns, ground cover and mulch shade the soil resulting in cooler soils during radiation frosts. Keeping the soil surface clean of mulch and vegetation allows it to absorb more heat during the day. Soils have a large heat capacity, so they can capture and store considerable heat during sunny days. This heat can maintain warmer air temperatures during cold nights. Mulches, weeds and sod insulate the soil surface from the sun. In addition, plantings of any kind under your plumeria raise the effective ground level, so even higher branches or tips become subject to injury where there is a tall stand of grass or weeds under your plants. (Note that frost forms on your lawn first.)
Important is the fact that wet or moist soils have a higher heat capacity than dry soils, and packed soils are able to absorb more heat than recently cultivated soils. This means that clean, moist, and packed soil surfaces will absorb more radiant energy during the day, and protect plants from frost by releasing this heat during the night. In general, un-mowed weeds ground covers or lawns are cooler than mowed covers, which are cooler than loose cultivated soils. Packed bare soils are warmer than loose soils and wet packed soils are the warmest of all.
All above mentioned products are available through "Kimis" Shop Plumeria by mail-order.
We hope this material is useful for to you in future winters. If you have any questions I can be contacted by telephone; (888)
819-4811
|
|
|
|
