IN THE GARDEN WINDY WEATHER MEANS WATER MUST BE PLENTIFUL.

Byline: JOSHUA SISKIN

If you live in a windy area, even the short days and cool temperatures of December do not allow any slacking off where watering is concerned.

Wind can be just as desiccating as dry heat. Even on a calm day, more than 90 percent of the water that roots absorb from the soil moves up through stems, into leaves, and out into the surrounding air by way of leaf pores.

Normally, an invisible, razor-thin layer of water vapor remains behind, hovering over leaf surfaces. However, on a windy day, this blanket of moisture is blown away as quickly as it is produced.

Planting now in windy weather is like planting in the middle of summer. Plants should be watered thoroughly while still in their containers and watered again as soon as they are placed in the ground. For two weeks following planting, they should receive a good soak at least once a day.

In Los Angeles, regardless of how strong the wind blows, relative humidity is lower in December than at any other time of the year. It is advisable to keep house plants, most of which come from the tropics, close to kitchen sinks and showers this time of year to maximize moisture in the air that surrounds them.

Most of the berries you see on ornamental plants this time of year are not poisonous. You can even eat them if you are really hungry, or turn them into jam. The most visible berries are seen on firethorn (Pyracantha). They are red or orange and borne densely on the plant, which is often trained as an espalier against a fence or block wall. All along its stems, firethorn has - wouldn't you know it - wicked thorns and, on account of this attribute, is also used as a living security fence.

Two related species are also flush with berries this time of year. One is red clusterberry (Cotoneaster lacteus) and the other is the native toyon (Heteromeles arbutifolia).

Another name for toyon is hollywood and, yes, tinsel town was named for this plant, which is indigenous to the Hollywood Hills. The first movie makers thought it resembled true holly and decided to name their new home after it. Incidentally, the berries of true holly, which is native to Europe, are poisonous. And speaking of poisonous, the most deadly plant in the world, the castor bean, grows wild in vacant lots all over the Valley.

This plant's botanical name is Ricinus communis, and ricin, the lethal chemical, is made from castor bean mash. The castor bean plant is highly ornamental, its sharply and deeply lobed leaves turning attractive shades of scarlet and burgundy in the fall. There are even named castor bean varieties that can be purchased from mail order nurseries. Just make sure you don't plant them near the kids' play area!

Q: I have a large pink hydrangea bush on the northeast side of my house and I'm not sure about the correct way and time of the year to trim it. Could you give me proper directions for pruning this plant?

- Amy Gladish, Tujunga

A: Do nothing until the weather warms in March or April. At that time, cut all gray-colored stems down to the ground and leave tan-colored or shiny brown stems alone. As is the case with a well-pruned rose, a well-pruned hydrangea should have the shape of a vase. Whereas a rose will generally show three to five canes after it is pruned, a hydrangea may have 10 or more stems. Cut these stems back to a height of 2 to 3 feet. Stems that are more than 2 years old or have branches should be cut out. By the way, when fertilizing hydrangeas, make shallow holes around the outside diameter of the plant for depositing your fertilizer. Should you want your pink flowers to come out blue, use aluminum sulfate fertilizer. For the new red-flowered varieties, super phosphate is the chemical of choice.

TIP OF THE WEEK: The best way to dry hydrangea flowers is simply to place them in old tea cups. Such flowers may last for up to two years or longer.