Keep your croton houseplant’s soil lightly moist at all times during the spring and summer months when the days are long and bright, since the plant reportedly transpires—“sweats” water off as vapor—a lot. As the days begin to shorten again in autumn, reduce the amount of moisture you give your croton, watering it only when its soil is dry 1 to 2 inches down. That helps protect it against the root rot that can become a problem with over-irrigated houseplants during winter.