When you go on vacation for longer than a week, your plants will need a little attention while you are gone. You can hire someone to care for your plants, or you can employ these techniques. Group plants to conserve humidity and moisture. Line a tray with pebbles and fill it with water to just below the top of the pebbles. Set the plants on the tray. This method also works on a day-to-day basis for plants that prefer high humidity.
Use this method in your bathroom: Set all your houseplants in the bathtub and turn on the shower to drench them. Drape a clear sheet of plastic over the plants, but keep it from directly touching them. They'll be fine like this for up to 2 weeks.
If there's no natural light, set up a fluorescent light on a timer to turn on 12 hours per day. Set individual plants in large, clear plastic bags, making a mini greenhouse for each. Cut a few slits in the bags, and tuck the tops of the bags under the pots. If it's winter, set the thermostat at 60-65 F when you leave. Your plants will fare better in a cooler atmosphere. If you ask a neighbor or friend to water your plants, leave a list explaining which days to water and including any special instructions for specific plants.