Lucky you, to be taking off for Brazil next month. Unfortunately, your neighbors are so envious that you don't dare ask any favors. So who will water your plants while you're gone?

The Plant Watcher will. An umbrella-like plastic terrarium, it keeps plants moist and happy for at least 10 weeks. You'll run out of money by then. Snap it open (avoiding the annoying powder with which it is coated). Find a good place on the floor, preferably facing a window with eastern exposure. Give your plant a farewell soaking and drain it thoroughly. Place it inside, zip the zipper shut and call your taxi. The Plant Watcher is 30 inches high and 30 inches in diameter, so measure your loved one before ordering. Succulents and some exotic plants may find the environment too moist, but most others should thrive. You could also use this as an isolation chamber, or for seedlings and cuttings. But don't try to bring back any cuttings from the jungle; the Department of Agriculture will get annoyed.

Plant Watcher. $20 ppd. Plant Watcher, 4801 N. 20th St., Arlington. 525-9310. If your plant doesn't fit the size terrarium mentioned above, call and inquire. Bigger and smaller sizes may be available, for $16 and $24, by the time you read this. Allow two to three weeks for delivery; start planning your trip early.