you can try wrapping your container (up to the stem, so just the soil is covered) with clear plastic to keep moisture in. this will probably only last a week, but if you use it with the water globe it might buy you some more time.
i found this online as well
(CBS) Have you ever come home from a long, relaxing vacation only to find your garden and houseplants have all dried up? Georgia Raimondi, author of The Passionate Gardener, shared some tips on keeping plants healthy while you're away on The Saturday Early Show.
Indoor Plants
The key to maintaining healthy plants while you're away is to make sure they have plenty of water. Houseplants should be repotted in containers that retain water. Terra cotta, wood and cement all allow water to evaporate quickly while containers made of plastic, fiberglass, metal or glazed ceramic retain water.
Also, avoid potting plants in dark pots that absorb heat and tend to dry out the soil faster. A light-colored or white pot will reflect heat and keep plants cooler.
Several products can help plants retain moisture over long periods of time.
Polymers, the small white granules in potting soil, can cut watering frequency in half. Using a pencil, poke several 2-inch deep holes in the soil (make sure the holes are deep enough to reach the roots but not too close to the center stems of the plant). Fill the holes with polymers, cover with soil, and water the plant thoroughly. Polymers can be purchased in garden supply stores by the pound. A one pound bag costs about $15 but lasts several seasons.
Terra cotta cones can help plants get plenty of water. These nifty devices are cylinders made of terra cotta with a cork ring on top. Push the top of the cone into the mouth of a plastic soda bottle filled with water. Invert the cone and the bottle and place the cone into the soil of your plant. The terra cotta will absorb the water from the bottle and release it slowly into the soil. Terra cotta cones cost $12.50 for three and can be found at Gardener's Supply Company,
www.gardeners.com.
Commercial plant watering wicks can keep plants moist. They look like shoelaces with a plastic knob at one end. Soak the wick in water until saturated. Water the plant thoroughly, place the plastic end of the wick into the soil of the plant and place the other end in a 16 to 32 ounce container filled with clean water, making sure to keep the container at a lower level than the water. The water will slowly diffuse into the soil and keep the plant moist for a week or two. The wicks are available at garden supply stores.
If you have several houseplants that require watering, find a large galvanized tub and line it with heavy plastic. Fill the tub about half way with soil. Water all your houseplants thoroughly and place them, pots and all, into the tub. Cluster the plants together placing the smaller pots, which will dry out faster, in the middle. Fill the remainder of the tub with soil. Cover the top of the soil with a generous layer of peat moss, water the container wel and place the tub near a sunny window. Your plants should be fine without additional watering for about two weeks. You can also try this idea in your kitchen sink or bathtub provided the area gets adequate sunlight.
hope this helps
if its very hot or you have a fan blowin directly on or above the soil it will dry out faster)
