Florida, in the southeastern United States, is called the Sunshine State. It grows more oranges than anyplace except Brazil. But Arctic air has damaged some Florida oranges and strawberries in recent days, and killed fish at tropical fish farms.

    The unusually long period of cold weather has shown how even warm climates can sometimes freeze over. But protecting plants and trees in the garden may not be too difficult if you follow a few suggestions.

    Sudden cold can be the biggest threat, especially after a warm period. Plants have not had a chance to harden their defenses. Those that are actively growing or flowering are at high risk.

    Try to choose plants that live best with cold weather, and planting areas that face west and south. Being near other growth may also provide warmth.

    Most frost damage takes place at night. Ice crystals form on the leaf surface. They pull moisture from the leaves and keep plant tissues from getting water.

    Cold weather is most likely to damage or kill plants that do not have enough moisture. So keep the garden watered. Moist soil absorbs more heat than loose, dry soil covered with mulch or vegetation.

    University of Arizona extension experts say covering plants and small trees with cloth or paper can help prevent frost damage. A one-hundred watt light bulb designed for outdoor use can also provide warmth. Some people place Christmas lights on young trees for warmth. The bulbs should hang below the leaves to let the heat rise into the tree.

    Cold is especially dangerous to citrus trees. Agricultural specialists at the University of California suggest putting paper or cloth around the trunk and central branches of young citrus trees.

    In Florida, as temperatures fell to record lows, citrus growers sprayed water on their trees to help prevent freeze damage.

    Jim Bottcher is a master gardener with the University of Florida extension. He explains that as the water freezes, it produces heat, and the ice forms a protective blanket around the tree. If you spray a tree, keep the water away from nearby power lines. Heavy ice can form and break them.

    You can also wrap a tree in palm tree frond leaves, cornstalks or fiberglass. Adding plastic film works well in rain and snow. But experts say plastic alone does not help much.

    氣溫下降時如何給植物和樹木保暖？

    佛羅里達州，位于美國東南部，也被稱作陽光之州，這個地區(qū)生長的桔子除了巴西之外比任何地方的都多，但是近來北極的冷空氣對此地的一些桔子和草莓有所傷害，農(nóng)場里的熱帶魚也被凍死了。

    長時間少見的寒冷天氣意味著溫暖的地方也會受到寒流襲擊，但是如果你能按下面幾點去做，在寒冷天氣時保護好花園中的植物和樹木也許不是件很難的事。

    突然的降溫是最大的危害，尤其是在溫暖的氣溫持續(xù)一段時間后氣溫的突然下降，植物還未來得及采取必要的防護措施，尤其是那些處于生長及開花期的植物所面臨的傷害最大。

    種植時選擇那些能耐寒的植物，種植地的選擇要面向西面和南面，或者靠近其他植物栽培也會起到保暖的作用。

    大多時候霜凍的傷害發(fā)生在夜晚，會在葉面形成冰晶，從而帶走葉面的水分，最終導(dǎo)致植物水分的流失。

    冷空氣對植物的損毀幾乎都是以這種方式--濕度不足，所以要保持花園濕潤，潮濕的土壤吸收的熱量比喪失的熱量要多，干燥的土壤還要用草木或植被覆蓋。

    亞利桑那大學(xué)分校的專家說，要用衣物和紙張給植物及小樹以覆蓋，這樣能有助于預(yù)防霜凍的傷害。在戶外也可使用100瓦的燈泡能給植物提供溫暖，有些人也把圣誕燈掛在小樹上使它得到溫暖，燈泡應(yīng)該掛在葉子以下使熱量能上升到樹上。

    冷空氣尤其對柑橘樹傷害最大，加利福尼亞大學(xué)農(nóng)業(yè)專家建議要將紙張或衣物纏繞在小橘樹的樹干及主枝上。

    在佛羅里達，氣溫降到有史以來最低，橘樹種植者將水噴灑在樹上以幫助預(yù)防冰凍的傷害。

    吉姆。波特切爾是佛羅里達大學(xué)分校的花園掌管人，他說，當(dāng)水結(jié)冰時會釋放熱量，由于冰的形成，在樹的周圍形成了一層保護毯。如果你給樹噴水時，一定要遠離高壓線，否則，冰凝結(jié)在電線上會使電線折斷。

    你還可以用棕櫚樹葉、玉米稈或玻璃纖維纏繞樹木，在雨雪天氣時還可以在外面再加固一層塑料薄膜，但專家指出如果單單使用塑料纏繞作用就不大了。