Answer: Watering is really a subjective thing. The amount and frequency depends upon the plants and upon the growing environment. I think more plants are harmed by overwatering than by underwatering. There are exceptions, but most houseplants like moist soil. What I do is immerse the pots in a slightly larger container of water to thoroughly soak the soil and drive out any air pockets around the roots. When air bubbles stop coming to the surface I take the pot out and let the soil drain well, then put the plant back in its regular place. When the top of the soil changes color it indicates it's beginning to dry out. I water thoroughly again, then let the soil begin to dry out again. Plants require less water in the winter and more in the spring and summer when they're actively growing.
There are a couple of helpful books you might want to read: "The Houseplant Expert" by Dr. D.G. Hessayon lists hundreds of plants and explains the culture for each. "Houseplants for Dummies" by IDG Books is another helpful resource. After reading these two books you'll be an expert in your own right and can keep your houseplants healthy and happy.
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