Handy Tips For "The Ride Home" of those new plants in any weather.        Transporting those new plants home from the nursery, isn't quite as complicated as "The Ride Home" when you take a newborn baby home from the hospital nursery, but there are some considerations to keep in mind so that those tender young plants aren't damaged before you even get them planted in your yard or garden.      After your new plant is out of the store, you have to make sure it weathers the ride home with a minimum of disturbance. The following information provides some tips for both cold-weather and warm-weather rides. Hot weather;      In hot weather, temperatures can reach as high as 170 degrees F (77 degrees C) in a car parked in bright sun, enough heat to do in the toughest plant. If you're driving home, try to keep the plant out of the hot sun by placing it on the floor of the car. If your return trip includes another stop, park the car in the shade and leave the windows open a crack. Better yet, don't stop on the way home. Make your plant purchase the last one of the day. Cold weather;      You can buy plants in any season, but in cold climates you need to take some special precautions during the winter months:      Insist on paper wrapping. It's a better insulator against cold than plastic.      If it's really cold out (below freezing), ask the clerk to double-bag the plant by placing the plant first in a sealed paper bag and then in a larger plastic bag. Inflate the outer bag by blowing it up, then tie it shut to trap the warm air inside.      In subfreezing weather, always heat the car before putting a plant inside. If you intend to set the plant on a cold floor or seat, put a layer of insulation between the pot and the cold surface. You also can ask the store for an extra paper bag and put that under the plant.      Never let the foliage touch a cold window.      Make sure that your plant purchase is the last stop for the day: Don't leave a plant sitting in a car that's getting colder by the minute.      If you bring a plant home by foot or by bus when temperatures drop well below freezing, you run a big risk of killing it. You don't want to have the plant outdoors any more than five minutes, even well wrapped.