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.

    气温下降时如何给植物和树木保暖？

    佛罗里达州，位于美国东南部，也被称作阳光之州，这个地区生长的桔子除了巴西之外比任何地方的都多，但是近来北极的冷空气对此地的一些桔子和草莓有所伤害，农场里的热带鱼也被冻死了。

    长时间少见的寒冷天气意味着温暖的地方也会受到寒流袭击，但是如果你能按下面几点去做，在寒冷天气时保护好花园中的植物和树木也许不是件很难的事。

    突然的降温是最大的危害，尤其是在温暖的气温持续一段时间后气温的突然下降，植物还未来得及采取必要的防护措施，尤其是那些处于生长及开花期的植物所面临的伤害最大。

    种植时选择那些能耐寒的植物，种植地的选择要面向西面和南面，或者靠近其他植物栽培也会起到保暖的作用。

    大多时候霜冻的伤害发生在夜晚，会在叶面形成冰晶，从而带走叶面的水分，最终导致植物水分的流失。

    冷空气对植物的损毁几乎都是以这种方式--湿度不足，所以要保持花园湿润，潮湿的土壤吸收的热量比丧失的热量要多，干燥的土壤还要用草木或植被覆盖。

    亚利桑那大学分校的专家说，要用衣物和纸张给植物及小树以覆盖，这样能有助于预防霜冻的伤害。在户外也可使用100瓦的灯泡能给植物提供温暖，有些人也把圣诞灯挂在小树上使它得到温暖，灯泡应该挂在叶子以下使热量能上升到树上。

    冷空气尤其对柑橘树伤害最大，加利福尼亚大学农业专家建议要将纸张或衣物缠绕在小橘树的树干及主枝上。

    在佛罗里达，气温降到有史以来最低，橘树种植者将水喷洒在树上以帮助预防冰冻的伤害。

    吉姆。波特切尔是佛罗里达大学分校的花园掌管人，他说，当水结冰时会释放热量，由于冰的形成，在树的周围形成了一层保护毯。如果你给树喷水时，一定要远离高压线，否则，冰凝结在电线上会使电线折断。

    你还可以用棕榈树叶、玉米秆或玻璃纤维缠绕树木，在雨雪天气时还可以在外面再加固一层塑料薄膜，但专家指出如果单单使用塑料缠绕作用就不大了。