Give houseplants a new lease on life. If more than a year has passed since the last repotting, replace existing soil with a new mix specifically designed for indoor plants. Wash the pot first to remove any crusty salt buildup. Also clean up the plant, removing dead or damaged foliage, and wash accumulated dust from the leaves. House plants may benefit from a new location during winter months, away from drying heat vents and near windows that offer more light and warmth. If adding holiday plants to the mix, remember that these winter-season plants like poinsettias, cyclamen and Christmas cactus need a cool spot to survive. Take care to avoid over watering too.