Plants grown in pots with a restricted amount of soil around their roots can easily become exhausted. To keep them looking and feeling healthy you must give them the right kind of nourishment (plant food) they need; also the correct amounts of light and water.
A perfectly healthy plant can soon decline as the nutrients can become exhausted. The plant would use up the nutrients and through constant watering the excess would be leached out from the soil. You would then need to top up the pot with a little more soil and nutrients. A standard fertilizer can be used. The Miracle Gro brand is widely available, safe and easy to use, providing you follow the instructions.
Miracle Gro All Purpose is suitable for the majority of house plants and Miracle Gro Bloom Booster is good for all flowering plants. These plant foods have balanced NPK (the macro-nutrients: nitrogen [N], phosphorus [P] and potassium [K]) along with trace elements and can be dissolved easily in water.
You would also need to refresh your potted plants by putting them out in the evenings for some fresh air.
More on caring for your plants next week.
Until next week, Happy Gardening