Selecting the right fertilizer for houseplants is one of the most practical ways to keep plants healthy and growing strong. Choosing the correct fertilizer for your indoor houseplants can be confusing, given the numerous products available on the market today. Understanding how different fertilizers work, what nutrients are required for continued growth, and how often applications are needed will go a long way in achieving success in growing indoor houseplants correctly.
What are the Nutrients Plants Need?
Primary nutrients, such as nitrogen, phosphorus, and potassium, are essential for growth. Secondary nutrients, such as calcium, magnesium, and sulfur, are necessary for the continuous growth and development of indoor houseplants. Micronutrients are trace elements that are required in small amounts. These types of micronutrients include iron, manganese, zinc, boron, copper, and molybdenum.
What does Nitrogen do for Plants?
Nitrogen is essential for all plants, including indoor houseplants. Nitrogen helps build chlorophyll, which captures light and enables photosynthesis. When more chlorophyll is present, indoor plants produce a greener color and healthier leaves. New growth is supported by nitrogen and continues to grow more aggressively. Nitrogen boosts plant vitality by helping indoor houseplants produce a healthy and full canopy and increases resilience.
Nitrogen deficiency is easily identified by older leaves turning yellow, slow and stunted growth, and weak-looking foliage. Nitrogen is essential for houseplants to produce energy and support overall plant growth. When nitrogen is deficient, photosynthesis is reduced, and the houseplant suffers, struggling to maintain healthy and vibrant leaves.
Phosphorus Benefits for Plants
Phosphorus helps keep indoor plants vigorous and healthy, providing the energy they need to grow new roots and blooms. Phosphorus is vital for building and increasing root depth and mass for indoor houseplants. Plants have more extensive and massive roots when they utilize phosphorus. The usage of phosphorus in fertilization programs for indoor houseplants increases flowering and blooming, and depends on phosphorus to maintain attractive blooms.
Plants that are deficient in phosphorus produce purplish leaf tissue, have stunted growth, reduced root or shoot growth, and have fewer or no blooms. Stronger roots, increased energy, and beautiful blooms are all benefits of having an adequate level of phosphorus within the soil and plant tissue.
Potassium Fertilizer Benefits for Plants
Potassium is essential for the growth of leaves and stems within plants. Potassium supports internal processes within plant tissue, enhancing plant strength and promoting balanced growth. Plants suffering from potassium deficiency are more prone to damage from pests, drought stress, temperature fluctuations, and root damage. One of the most essential benefits of potassium in houseplants is its ability to regulate water management with efficient hydration.
Potassium facilitates the internal transportation of nutrients to where they are needed, thereby improving nutrient efficiency and plant performance. Leaves maintain firmness, and stems remain firm, vibrant, and strong with adequate levels of potassium. Symptoms of potassium deficiency include brown or scorched leaf edges, weak stems and drooping growth, reduced resilience to diseases, and older, pale leaves.
Micro Nutrient Benefits for Plants
Micronutrients make up a tiny percentage of the overall composition of a houseplant. They have a tremendous impact on the health, color, and overall vitality of indoor houseplants. When micronutrients are not present, plants can’t fully use nitrogen, phosphorus, and potassium to carry out regular plant functions. Micronutrients like iron, manganese, and magnesium are essential for the formation and maintenance of the green pigment chlorophyll within plants. Energy production and stronger growth are not possible without the presence of these micronutrients. Photosynthesis is enhanced with micronutrients such as iron, manganese, chlorine, and copper because they are directly involved in the photosynthetic process.
Boron, zinc, and copper aid in the proper growth of plant roots by enabling them to absorb nutrients more efficiently and produce stronger plant resilience. Micronutrients work with internal plant enzymes to protect indoor houseplants from drought, pests, and diseases. Additionally, micronutrients regulate plant hormone activity, which increases growth, flowering, and nutrient processes such as absorption. Micronutrients help activate many growth processes within indoor houseplants.
Why Do Plants Need Fertilizer?
Plants that are grown as indoor houseplants require nutrients to continue growing. Unlike outdoor plants, indoor plants do not have access to the soil's natural elements that provide essential nutrients for growth; therefore, they must be supplied with a proper balance of nutrients. Natural soil continuously replenishes itself with natural fertilizers required for plant growth. Indoor plants do not have this luxury and require specialized indoor plant fertilizers to maintain their vitality. Soils used for indoor houseplants have limits on the amount of nutrients that can be supplied. Plants will absorb all of the nutrients within this particular soil and create nutrient deficiencies once the required nutrients have been depleted.
Additional indoor houseplant fertilizers are necessary for continued growth and optimal plant function. Liquid plant fertilizers are very convenient as they are already in a form that is broken down and readily available to the plant. Without the presence of nutrients in the indoor potting soil, plants slow in growth and halt their natural plant functions. Macronutrients and micronutrients maintain the green color of leaves and prevent yellowing and other symptoms of nutrient deficiency. Indoor plant fertilizers provide plants with essential nutrients that are not fully present in potting soils used for indoor plants, as they are depleted over time.
How Much Fertilizer Do Plants Need?
Indoor houseplants do not require the same amount of fertilizers as outdoor plants, but they do need the same indoor plant fertilizers in smaller amounts. The exact amount depends on what type of plant is being grown. Usually, indoor plants prefer lighter or spoon-feeding applications. As a general rule, using indoor plant fertilizers at half the rate or strength is a safe practice. This reduces the possibility of excessive salinity within the soil (salt buildup) and nutrient burn in pots and containers.
Indoor plants can grow year-round, but are more active during the spring and summer months and less active during the fall and winter months. Fertilizing every 2 - 4 weeks in the spring and summer and then monthly or less in the fall and winter will supply indoor plants with the nutrients to grow. Slow-growing or sensitive plants perform best when indoor plant fertilizers are applied at a rate of ¼ or ½. Flowering and fast-growing plants may need more frequent fertilization at a ½ rate.
Using a balanced and complete indoor plant fertilizer that contains nitrogen, phosphorus, and potassium, as well as essential micronutrients such as iron, manganese, and zinc, is ideal for overall health and optimal plant performance. Applying too much indoor plant fertilizer can cause brown leaf tips, yellowing and drooping leaves, form a white crust on the soil surface, and reduce growth and rooting. Indoor houseplants grow consistently with supplied nutrients at a reduced rate, avoiding many serious issues associated with indoor growth.
How to Tell What Fertilizer Plants Need?
One of the most common signs of a nutrient deficiency within indoor houseplants is yellowing leaves. The older leaves yellow first as a sign of nitrogen deficiency. When newer leaves turn yellow first, it is often a sign of a deficiency in iron or manganese. Indoor plants that stop growing or producing new leaves may be lacking nitrogen, phosphorus, or micronutrients. Leaves that lose green color are usually a symptom of nitrogen, magnesium, or iron deficiency.
Brown or crispy leaf edges are associated with potassium deficiency or salt buildup within the potting soil. This can also be related to over-fertilization. Purple or dark tints on leaves are often caused by phosphorus deficiency and are more noticeable on the underside of the leaves and stems. Weak or thin growth indicates a lack of nitrogen and inadequate light exposure. When leaves turn yellow, but veins stay green, it is a sign of iron deficiency, magnesium deficiency, or manganese deficiency.
Poor flowering or no blooms are often associated with low phosphorus and potassium levels, as well as a general nutrient imbalance. Leaf deformities or abnormal growth can be related to deficiencies of boron, calcium, or zinc. Slowed root growth or development mass can be associated with phosphorus, calcium, or boron deficiency. Most nutrient deficiency symptoms can closely resemble other symptoms, such as under-watering, overwatering, low UV ray or light exposure, damage from indoor pests, or root-bound plants.
The Best Houseplant Fertilizer
There are many indoor plant fertilizers available to meet your plants' needs. The overall goal of fertilizing indoor houseplants is to provide sufficient nutrients to support normal growth and plant functions. Large amounts of fertilizer are not required and are unnecessary for indoor growth. There are various forms of granular, liquid, slow-release, quick-release, and balanced-release products that can be applied to indoor houseplants.
Selecting the correct one depends on the type of plants being grown indoors and their nutrient requirements. Micronutrients that are commonly deficient in houseplants require replenishment on an annual basis. Simple Lawn Solutions 4-6-8 Plant Food can supply 4% nitrogen, 6% phosphorus, and 8% potassium.
Additionally, Simple Grow Solutions 4-6-8 Plant Food Fertilizer contains humic acid and seaweed extract. This blend is a perfect source and liquid plant fertilizer for indoor houseplants. It is an excellent all-purpose liquid fertilizer for most plants. The 4% nitrogen encourages greening and vertical growth. With 6% phosphorus, it provides nutrients for resilient plants and root development. The 8% potassium encourages plant hardiness and supports normal plant functions. Humic acid makes applied nutrients more available to the plant, while seaweed extract adds organic matter.
Benefits of NPK: All-Purpose Plant Fertilizers Nutrient Needs
Indoor houseplants require the same types of nutrients that outdoor plants need, but in smaller quantities and less frequently. Fertilizing indoor houseplants requires applications of a ¼ to ½ rate to maintain a good growing environment. Micronutrients are also needed on an annual basis because the soil is often limited in providing these essential nutrients in an indoor environment. Depending on the type of indoor plant being grown, rates will vary between ¼ - ½ rate applications. Unlike outdoor plants, indoor plants do not have access to the soil's natural elements that provide essential nutrients for growth; therefore, they must be supplied with a proper balance of nutrients to support their development.
Using a balanced and complete indoor plant fertilizer that contains nitrogen, phosphorus, and potassium, as well as essential micronutrients such as iron, manganese, and zinc, is ideal for overall health and optimal plant performance. Indoor plant deficiencies can be identified by changes in leaf color, health, and structure, as well as reduced or abnormal growth. Simple Lawn Solutions 4-6-8 contains humic acid and seaweed extract, making it a perfect source and liquid plant fertilizer for indoor houseplants.
References:
https://extension.umd.edu/resource/fertilizer-indoor-plants/
https://sturf.lib.msu.edu/article/2013feb8a.pdf
https://msu-prod.dotcmscloud.com/home_gardening/uploads/files/FertilizerBasics-2020-web.pdf
https://simplelawnsolutions.com/products/all-purpose-plant-food-4-6-8-32-ounce
