Guide to Fertilizing Indoor Plants
It is difficult for people to understand how to fertilize plants because they have very different nutritional needs than we do: it is easy to make mistakes or feed too frequently or too much. The purpose of this article is to explain how plant nutrition works and indicate how to fertilize indoor plants to make them thrive.
Fertilizer consists of nitrogen, phosphorus, and potassium, along with micronutrients that are necessary for plant growth and energy. For best results, feed houseplants a balanced formula at half strength, once per month. The more diluted a solution is, the better it is for succulents. Leafy plants prefer nitrogen; flowering plants need phosphorous and potassium.
Why Plants Need Fertilizer
Plants and animals consume nutrients from their environment to support their growth and survival, but the similarities end there. Thanks to photosynthesis, plants and animals use different kinds of nutrients. In thinking about fertilizer, it might be helpful to consider it as a multivitamin rather than a meal.
In spite of the fact that nutrients are necessary for photosynthesis, they do not need to be in the concentrations required for animal nutrition. The conversion of sunlight into complex physical matter occurs through the use of comparatively simple elements.
As part of the process of photosynthesis, carbohydrates are produced and used to fuel the plant and build its roots, stems, leaves, flowers and fruits. Light, in a sense, is the plant’s most important food.
Why You Need To Fertilize Indoor Plants
In their natural state, decay helps return nutrients to the soil, but in an artificial setting, such as a container, that process cannot occur. Furthermore, houseplants exhaust the nutrients in the soil, and most potting mixes are unfertile to begin with. Potting soil is also drained of its nutrients with each watering.
Several elements are required to complete the complex chemical reactions of photosynthesis, which is why they should be replenished by fertilization.
Still, plants require only a little care. They only require fertilizer during the growing season, which may last all year round for tropical plants. However, over-fertilizing a plant when it is going through a dormant phase could be harmful.
What Do Indoor Plant Fertilizers Contain?
An essential element in plant nutrition is nitrogen, phosphorus, and potassium. These three elements have led to the development of a labeled standard for consumer information.
NPK Numbers
NPK ratios are notated on fertilizer labels as three numbers separated by a dash. The ratio will appear on fertilizer labels as three numbers. 10-10-10, 2-3-1, and 20-10-10 are examples you might see. They are arranged by how much nitrogen (N), phosphorus (P), and potassium (K) are present.
In percentage terms, the size of the number represents how much of each substance is present. For instance, an NPK ratio of 2-2-2 contains the same proportion of elements as in a 10-10-10 or 20-20-20 formula. In smaller numbers, the amount of an element is lower in relation to the total mix.
Macronutrients
For plant growth, each of the three major nutrients is vital, but each is used in a different way:
Nitrogen – This is the primary macronutrient for leaf growth. The amino acid plays a crucial role in metabolism and protein synthesis, affecting many of the above-ground parts of a plant. Leafy tropical plants tend to benefit from a high nitrogen percentage.
Phosphorus – This element is important for producing strong roots, flowers and fruits. Phosphorus is essential to the transport and storage of nutrients. Although it is required for growth, it becomes especially critical during the flowering phase.
Potassium – This basic nutrient aids plant metabolism and the transportation of the plant’s reserves. This compound contributes to the strength of the plant and aids in flowering and fruit production.
Micronutrients
Other elements, called micronutrients, are needed in smaller quantities by plants too, and only make up around 1% of their dry weight and do not need to be given in bulk. These elements can cause poisoning when present in sufficient quantities in the soil.
In organic fertilizers, micronutrient levels and variety are usually higher than in synthetic-quality fertilizers, but the amount of micronutrients added isn’t as specified. Synthetic fertilizers contain micronutrients that can be more precisely specified.
The following three micronutrients are also called secondary macronutrients since they are required by plants in significant quantities:
The cellular growth process and the construction of cell walls, as well as mineral transport and retention, require calcium.
The mineral magnesium is critical to photosynthesis, because it is a key component of chlorophyll. Magnesium is also essential to the activation of numerous plant enzymes.
Besides being an essential component of chlorophyll, sulfur plays a major role in plant metabolism and helps plants utilize nitrogen. Sulfur contributes to the synthesis of protein and tissue as well.
Other essential micronutrients include Boron (B), Chlorine (Cl), Copper (Cu), Iron (Fe), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), and Zinc (Zn).
There are also many trace nutrients commonly used by plants that haven’t been proven essential, including Cobalt (Co), Silicon (Si), and Sodium (Na).
Bioavailability
The presence of an element in the soil alone is not enough: it must also be accessible and usable by the plant. Certain nutrients may be present in soil tests but are not available to be utilized by plants in photosynthesis.
Bioavailability is also affected by the type of soil, its organic content, temperature, and other physical, biological, and chemical conditions. pH controls whether a plant can utilize a specific element.
In fertilizer formulations, the key bioavailability factor is whether the nutrient is present in a form that is compatible with the plant’s chemistry. The results are cheap synthetic fertilizers with great-looking labels, but the ingredients actually provide little plant nutrition.
Bioavailability is one of the characteristics of organics that makes them ideal for this application.
How Often To Fertilize Indoor Plants
A balanced fertilizer that includes micronutrients works well with many houseplants when diluted to 50%. It is usually recommended to fertilize indoor plants once a month through the growing season. Others prefer to fertilize more frequently with a more concentrated solution.
Slow-growing plants like succulents and other herbaceous plants generally benefit from monthly applications of a quarter-strength solution.
Depending on the plant and the climate in your area, you may need to feed continuously if the plants are growing year round in a tropical climate; if your area has seasons, you may need to curtail feeding when cool weather arrives.
It must be noted that there are some exceptions. Many plants grow in the winter indoors – make sure to feed if you continue seeing new growth. Sometimes plants grow on their own schedule.
Using liquid fertilizer dissolved in water or a dry mix dissolved in water enables you to control the dosage and ensure the soil is evenly saturated.
You won’t need as much as the majority of manufacturers recommend, and too little works better than too much. Dilute the formula to half strength or even quarter strength.
Before applying the fertilizer, you should water the soil. Dry soil sets the plants up to absorb moisture, which can cause the plants to overfeed themselves.
Concentrated fertilizers tend to leave spots or burned patches upon contact with leaves. Use a narrow spout watering can to get as close to the soil as possible so that you don’t splash the foliage.
Fertilizing Needs Of Different Plants
Species preferences play a big role in fertilization. Research your species to determine whether it’s a heavy feeder or a light feeder.
The nitrogen percentages of fertilizer for leafy houseplants tend to be higher once established, while succulents prefer a lower percentage and may benefit from dilutions of about 14%.
During the flowering period, flowering plants require more phosphorus and potassium compared to non-flowering plants. Continuously blooming plants, including African violets, need special formulas throughout the year.
Often growth in annuals and vegetables is heavy, so fertilizer should be applied every two weeks or more frequently.
Tips For Fertilizing Indoor Plants
Don’t use too much fertilizer; too little is better than too much. Make sure to follow retailers’ recommendations by using half the recommended dosage.
For safe and effective fertilization of indoor plants, follow these tips:
Using convenient slow-release fertilizers involves too much guesswork; for that reason, organics are the best choice.
Nitrogen-rich fish emulsion can be used as a fast-acting organic fertilizer for leafy houseplants, though it stinks! It is diluted in a high concentration as part of regular watering. A quarter of a teaspoon per gallon should be fine. You may want to perform this dilution outside. Yes, it’s that bad.
Use seaweed extract to further reduce the smell; it provides a host of micronutrients and complements the ingredients in fish emulsion.
You shouldn’t use unsterilized compost for indoor plants because the chances of disease and pest infestation are greater. It’s easier and safer to purchase compost at a retailer.
Synthetic fertilizers can burn the tender roots of seeds, so dilute them to at least a quarter of the recommended strength. Organic fertilizers are safer but may encourage rot, so dilute them by at least half. The rule to feeding seedlings is: weakly, weekly. Seedlings should be fed once a week after their first true leaves appear.
When to feed a newly purchased or gifted plant depends on the type, condition, and season, so check the soil for small colored balls that indicate slow-release fertilizer pellets. If you see these, wait four to six months to let the nutrients leach out.
Fertilizing sick plants does no good and can even make the situation worse. Plants only need a limited amount of nutrients, so you can’t overfeed them.