How to Fertilize Indoor House Plants

There is a lot of conflicting advice online and in books about fertilizing houseplants. Fertilizing isn't complicated, yet so many people struggle to do it correctly. That's understandable with so much contradictory information. Houseplants are just as likely to be over-fertilized as under-fertilized, and it is important to understand the reasons why. Applying fertilizer at the right time and in the right amount goes a long way in ensuring the vitality of your houseplant.

Why Do Houseplants Need Fertilizer?

Over time, the potting soil your houseplant resides in loses nutrients. This is natural and expected. Fertilizer replaces the lost nutrients and provides the plant with the food it needs to stay healthy and happy. All houseplants need fertilizer on a scheduled basis. 

Do:

• Learn about your plant and its needs before applying anything. Plants do not have the same fertilizer needs. The best way to be successful is to be educated.
• Fertilize your plants when they are in an active growth. This will vary based on the type of plant, but usually, that is spring and summer.
• Set a schedule for applying fertilizer based on the type of plant and where it is in the growing cycle. This way, you won't forget. Houseplants won't tell you when they need fertilizer; they depend on you to anticipate their needs.
• Use a complete fertilizer, one with a balanced ratio of nitrogen, phosphorus, and potassium. These are the three essential nutrients for a houseplant.
• Read the label of the fertilizer and follow the instructions. Each brand and type is different as far as potency, which means it will require different application timing than another brand. 
• Flush the soil every four months with lots of water to remove excess salts that build up over time from the fertilizer. Run water through the soil until it drains freely from the bottom.
• Apply fertilizer to the soil that is already moist to prevent damage to the roots.
• If fertilizer is going to be applied on a monthly, weekly, or biweekly basis, choose water-soluble powder or liquid concentrate.
• If fertilizer is going to be applied at intervals longer than a month, choose a time-release or pelleted application.

Don't:

• Don't fertilize during winter months (or the specific plant's down-time). Plants need rest, just like all other living things. In the winter, they rest and preserve their strength so that they can dazzle you in the spring and summer.
• Don't ever apply more fertilizer than is instructed on the label. More is not better, especially when it comes to fertilizing houseplants.
• Don't neglect to flush the soil. Excess salt prevents plants from taking up water and may stunt the growth.
• Don't use fertilizing as a means to stimulate flower or plant growth. Fertilizer is a boost, not a cure. If the plant is struggling, it is more likely that it lacks sun, is getting too much sun, or there is an issue with watering. Adding extra fertilizer may actually hurt the plant.
• Don't apply fertilizer to a wilted plant. Water the plant and let it recover before adding any fertilizer.