- By adding fertilizer to houseplants, they get adequate nutrients to grow and maintain their health.
- Fertilizer typically displays three numbers, referred to as the N-P-K ratio.
- Nitrogen (N): Necessary for the development of the plant’s leaves and stems.
- Phosphorous (P): Used in photosynthesis and formation of DNA and cell membranes, as well as for root growth and flowering.
- Potassium (K): Essential for photosynthesis, respiration, and water balance regulation. Also for the growth and development of roots and shoots.
- Plants typically need fertilization every four to six weeks during the growing season from March to September.
- Avoid or give very little fertilizer during the winter months because many plants go dormant and don’t need as many nutrients.
- There are several types of fertilizers available for indoor plants:
- Liquid fertilizer
- Granular fertilizer**
- Organic fertilizer
- Fertilizer sticks
**Click here to skip down to what fertilizer we like the best. We use it ourselves and have had great success.
Table of Contents
- 1 Key Takeaways
- 2 Why Fertilize Houseplants?
- 3 When and How Often to Fertilize Plants?
- 4 Types of fertilizers
- 5 FAQ
- 6 References
Houseplants can brighten up any room, but some plants need to be fertilized regularly to stay healthy.
When you fertilize houseplants, you give them the nutrients they need to grow.
We will discuss and compare different kinds of fertilizers, the best time to feed them, and how to fertilize houseplants.
For more information on houseplants, please visit our Houseplants main page.
Why Fertilize Houseplants?
Houseplants require adequate nutrients to grow and maintain their health.
Fertilizing houseplants provides them with essential nutrients that may be lacking in the soil, especially when they grow in containers with limited resources.
Fertilization, when done correctly, supports healthy growth, blooming, or the production of new leaves and helps plants resist diseases and pests.
Nutrients Required for Houseplants
Nutrients needed by plants are divided into two categories: macronutrients and micronutrients.
There are three primary macronutrients necessary for healthy houseplant growth: nitrogen (N), phosphorus (P), and potassium (K). These macronutrients are typically indicated on fertilizer packaging as N-P-K ratios.
Understanding fertilizer labels is essential for selecting the right nutrient blend for your houseplants. A fertilizer label typically displays three numbers, referred to as the N-P-K ratio.
- Nitrogen (N): Formation of proteins, nucleic acids, and chlorophyll. It is also necessary for the development of the plant’s leaves and stems, as well as its overall growth.
- Phosphorous (P): Involved in processes such as photosynthesis, respiration, and energy transfer. It is also necessary for the formation of DNA and cell membranes, as well as for root growth and flowering.
- Potassium (K): Essential for processes such as photosynthesis, respiration, and water balance regulation. It is also necessary for the activation of enzymes involved in protein and carbohydrate synthesis, as well as the growth and development of roots and shoots.
Plants also require micronutrients such as calcium, magnesium, and sulfur, as well as trace elements like iron, manganese, zinc, copper, molybdenum, and boron for optimal growth.
- Iron (Fe): Involved in processes such as photosynthesis, respiration, and nitrogen fixation.
- Manganese (Mn): Contributes to photosynthesis and respiration. It also aids in the activation of enzymes involved in carbohydrate breakdown and nitrogen metabolism.
- Zinc (Zn): Helps with photosynthesis and respiration. It also helps to activate enzymes involved in carbohydrate digestion and nitrogen metabolism.
- Copper (Cu): Photosynthesis, respiration, and the formation of lignin are all processes that copper is involved in. Also aids in the activation of enzymes involved in ethylene synthesis.
- Boron (B): Many processes, including cell wall formation, pollen tube growth, and calcium uptake, rely on it. It also aids in the activation of enzymes involved in carbohydrate and nucleic acid metabolism.
When and How Often to Fertilize Plants?
Unfortunately, there is no straight answer on the timing and frequency you fertilize your houseplants.
Generally speaking, indoor plants such as monstera, philodendrons, and succulents typically require fertilization every four to six weeks from the end of March to the middle of September.
However, the general rule for all plants is fertilization is beneficial to most houseplants during their active growing season, which is usually spring and summer. Avoid fertilizing during the winter months because many plants go dormant and don’t need as many nutrients during this period of the year.
Also, any fertilizer you use should be diluted to half the recommended strength for the several times you give it to your plant. We highly suggest that you follow the label directions for fertilizer and dilute the solution.
Over-fertilization can be harmful to your plants because it causes an accumulation of excess salts, which can cause root and leaf burn.
It is critical to exercise caution when it comes to the amount and frequency of fertilization.
Keep an eye out for signs of overfertilization, such as yellowing leaves or stunted growth. If you suspect a problem, water the soil to help remove excess fertilizer salts.
The bottom line is always on the conservative side and fertilizes as little as possible because you do not want your plant to be overfertilized.
Types of fertilizers
There are several types of fertilizers available for indoor plants, and each type has its own advantages and disadvantages. Below, we go over the various types you can use.
Liquid fertilizers are a popular choice for houseplants, as they can be easily mixed with water and applied during regular watering sessions.
They are typically water-soluble, which ensures quick and efficient absorption of nutrients by the plant roots. It is important to follow the label instructions for the correct dilution ratio and frequency of application, as this varies depending on the specific plant’s needs in terms of nitrogen, potassium, and phosphorus requirements.
However, because liquid fertilizer is quickly absorbed by plants, they do not provide a long-lasting supply of nutrients compared to granular fertilizers. Additionally, liquid fertilizers may be more expensive than other types of fertilizers, and they can be messy to apply if not used properly.
Granular houseplant fertilizers provide a slow-release source of nutrients for your plants.
They can be mixed in with the soil around your plants, ensuring a gradual nutrient distribution as the plant roots grow.
Granular fertilizers work well for larger plants or those with long-lasting blooms, as the gradual release of nutrients keeps the plants healthy and vibrant for a longer period of time.
However, be sure not to apply too much, as this can damage delicate root systems. Granular fertilizers can be “hot,” containing high levels of nitrogen and potassium that can burn plant roots.
With that said, granular fertilizer is the one type we like best. We prefer to use this slow-release granular fertilizer for all of our indoor plants. It makes it easy for us in that we can set it and forget it for up to four to six months.
Organic fertilizers are derived from natural sources such as compost and compost tea, manure, worm castings, seaweed extracts and liquid kelp, fish emulsion, and bonemeal.
These materials provide essential nutrients for plant growth and offer other benefits, such as improving soil structure and fostering the growth of beneficial soil microbes.
The problem with using organic fertilizers is that they can are less precise in their nutrient content, making it more difficult to ensure that plants receive the proper balance of nutrients. Further, they can contain higher levels of micronutrients such as copper, zinc, and boron which would be toxic to plants.
Organic fertilizers are also more difficult to buy than liquid and granular fertilizers. Plus, if you plan to make your own organic fertilizer it takes some extra effort to prepare.
Finally, some organic fertilizers, such as compost tea and fish emulsion, have a very smelly odor that you may not want around your plants.
Fertilizer sticks or spikes
Fertilizer sticks, also known as fertilizer spikes, are another convenient option for houseplant care. These solid sticks or spikes contain pre-measured amounts of nutrients and can be inserted directly into the soil around the plant.
They gradually release nutrients into the soil as the plant receives water, ensuring a consistent nutrient supply throughout the growing season.
They are super simple to use, simply press the recommended number of sticks into the soil, spaced evenly around the container, and water the plant as usual.
The downsides are fertilizer sticks for houseplants is that they can cost a bit more than other types of fertilizer.
They may not work as well for plants that need specific nutrients, like phosphorus, which can’t get any closer than the individual stick. Also, it can be hard to get fertilizer sticks out of the ground once they have been put in, and they may not fix nutrient deficiencies right away.
Lastly, some pets like to eat these sticks and will get sick – don’t use them if you have small pets.
How often should I fertilize my houseplants?
As a general rule, fertilize your houseplants every two to four weeks during the growing season (spring and summer) and every four to six weeks during the dormant season (fall and winter). However, the specific timeframe will depend on the specific houseplant and the type of fertilizer you’re using.
What type of fertilizer is best for my houseplants?
The answer really depends on the specific type of houseplant. Different types of houseplants have different nutrient requirements, so it’s important to do your research. As a general rule, use a balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium for most houseplants.
Is it possible to overfertilize my houseplants?
Yes, it’s definitely possible to over-fertilize your houseplants. Too much fertilizer can burn the roots and damage the plant. Always follow the instructions on the fertilizer packaging and don’t exceed the recommended dosage.
Can I make my own organic fertilizer for my houseplants?
Yes, you can make your own organic fertilizer for your houseplants using ingredients like compost, worm castings, and seaweed extract. Just be sure to research the specific nutrient requirements of your houseplants and adjust the recipe accordingly.
Do different types of houseplants require different fertilizers?
Yes, different types of houseplants have different nutrient requirements and may require different types of fertilizers. For example, plants that prefer acidic soil may require fertilizer with a lower pH. Do your research and choose a fertilizer that’s appropriate for your specific houseplant.
Lindsey Hyland grew up in Arizona where she studied at the University of Arizona’s Controlled Environment Agriculture Center. She continued her gardening education by working on organic farms in both rural and urban settings. She started UrbanOrganicYield.com to share gardening tips and tactics. She’s happy to talk about succulents and houseplants or vegetables and herbs – or just about anything in a backyard garden or hydroponics garden.