I have two large Bamboo plants in Pots, whats the best way to care for them?

What kind of soil are your plants in? Most houseplant soils are 90% peat. Peat is very hard to get wet at first, but once it is wet it will hold it's water for a long time. Try watering a little less frequently. A good way to gauge whether they need watering is to insert a chopstick into the soil, all the way down to the bottom and leave it in place for about twenty minutes. After twenty minutes remove the chopstick. When only the bottom inch or so of the chopstick is moist, then your plants need watering. If more than one inch is moist, hold off watering until it is a bit drier.