Answer: For convenience sake, you can fertilize your houseplants once every 2-3 weeks with a half-strength dilution of liquid fertilizer such as Peter's, Miracle-Gro or Shultz's. This method of feeding provides a nearly constant source of nutrients to the roots of your plants without concern for over-feeding.
As for watering, it depends upon the plants and the size of the rootmass (not the size of the pots). Thoroughly water all your plants. Then wait 3-4 days and either pick the pots up (dry pots will be lightweight). If the pot is still heavy, you won't need to water for a few more days. Or, you can stick your finger into the soil; if it's moist 1" below the surface, it won't need to be watered for a few more days; if it is dry, it's time to water.
Best wishes with your houseplants.
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