The coldest weather in several years will hit the Valley the next few days, putting some plants and many water pipes at risk of freezing.

The National Weather Service is calling for morning low temperatures below freezing from Saturday morning through Tuesday morning.  Low temps are expected to range from the low 30s in central Phoenix to the mid 20s in outlying desert areas.

The last time Phoenix recorded four consecutive lows below freezing was 24 years ago, in December of 1988.

Plants that are sensitive to cold temperatures should be covered to prevent them from dying.  Plant experts suggest watering the ground around sensitive plants around dusk, which will help to keep the ground warm.

Then, garden centers and some other stores sell "frost cloth" to cover the plants, which is designed specifically to keep plants about five degrees warmer than the air temperature.  Plant experts caution that many other materials won't work well:

• Burlap or blankets may be too heavy and crush plants;

• Bed sheets are too thin and only provide 1-2 degrees of protection;

• Plastic tarps don't effectively keep out the cold air, and also don't let plants breathe.

If you don't have frost cloth, lightweight bath towels or beach towels may be used for small plants.

Another danger from the freezing weather is to water pipes, which can crack if the water inside freezes and expands.  Because freezing temperatures are so rare, many Valley homes have water pipes that are exposed to the outdoors where they enter the house, and/or that run through the attic.

If your attic is uninsulated, or if you have exposed water pipes, the Phoenix Water Department suggests you install insulation around them, or at least wrap them in a towel or blanket for the next few days.

The Water Department's Ken Kroski suggests you also disconnect any hoses that are hooked up to outdoor water spigots.  He says if there's residual water in the hose, it can back up into the spigot and pipe and freeze, causing the pipe to crack.

He says another way to prevent frozen pipes is to keep a trickle of water flowing in one of your sinks during the overnight hours.  Water that's moving doesn't freeze as easily as stagnant water.