There are many reasons why we love African violets, but the fact that they bloom tops the list. Very few other plants in the world can live in our homes and bloom so often with minimal care. Sometimes, however, even violets can pout and not bloom as well as we might like. Fertilizer is an essential part of keeping houseplants happy-and that includes your dainty African violet. Sometimes new growers don’t fully understand the importance of a balanced diet, leaving them scratching their heads besides lackluster plants.
But developing a feeding routine can feel daunting; what’s the best type of fertilizer? This novice-friendly guide to African violet fertilizer will get you up to speed with what it takes to grow a healthy, hearty houseplant.
Like humans, plants convert nutrients into energy to function. But instead of chewing their lunch, they absorb it. Using their roots, plants soak up nutrients in the soil. Indoor plants, however, need a little helping hand. Because they grow in limited soil, and there’s no decaying matter to complete the cycle, they eventually use up all of the nutrients available. Fertilizer replenishes the nutrients plants use to grow.
Total depletion is a slow process; plants can survive for quite some time without a soil refresh. But surviving isn’t thriving, and with flowering plants like the African violet, that usually means no beautiful blooms. That’s because it takes a lot of energy to put on a colorful show. Imagine running a marathon on an empty stomach and no sleep-you might not be up to the challenge. There’s a reason you can’t survive on pizza rolls alone. They don’t contain all of the nutrients you need to function. (Shoot!) Your plant needs a balanced diet too.
Let’s clear the air of a big misconception. Fertilizer is not food. Plants make their own food and fertilizer helps them do it.
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That’s why most commercial fertilizers contain three primary elements: nitrogen, phosphorus, and potassium.
- Plants absorb more nitrogen than any other nutrient. Nitrogen fuels new growth and is essential for plant health.
- Plants need phosphorus to transfer and store energy. This nutrient also aids in photosynthesis.
- Potassium strengthens and fortifies plants, which helps them resist disease and grow strong root systems.
When you look at the product label you will see three numbers, such as 9-3-6 or 10-10-10. These numbers represent the percentage of a specific nutrient. It is an industry standard that those numbers will always represent nitrogen, phosphorus, and potassium. They will always be in that order.
Understanding the Essentials: N-P-K
A simplified way to remember what the big three do is: up, down, all around. Nitrogen helps with green vertical growth. Phosphorus helps with roots (and flowers). Nitrogen is the most needed nutrient for plants. Nitrogen promotes green growth and helps with other biological processes.
When a plant is lacking nitrogen symptoms of deficiencies will show up in older leaves first. We will also see poor new growth that will be lighter in color. Most species and older cultivars of violets naturally have a light green color to their leaves. Knowing what your plant should look like will help determine if the plant is lacking nitrogen.
When you look at the product label you will notice that nitrogen could have two or three different types. Most often we see ammoniacal, nitrate, and urea nitrogen listed. Typically urea is not plant ready until converted to ammonium by bacteria. That bacteria may or may not be present in a potting mix. Using only one formulation of nitrogen can also affect the soil pH (acidity or alkalinity). It is best to use a product that has at least two formulations of nitrogen such as ammoniacal and nitrate.
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Phosphorus is the second most needed nutrient. Phosphorus helps with root development, encourages flowers, and other biological functions. When a plant is deficient in phosphorus we often see leaf tips on older leaves browning following by turning dark green with a purplish hue on the backside of the leaf or the petiole. This can be challenging to diagnose because many of our violet cultivars have a red back.
Potassium is the third most needed nutrient for plants. Potassium helps with the overall plant health. It will aid in the movement of water, nutrient flow, carbohydrates, and other biological processes. When a plant is lacking potassium we will see weak stems, yellowing of older leaf tissue (chlorosis) followed by localized death of tissue.
Soil pH and temperature of the growing space will also affect the availability and uptake of nutrients by the plants. Traditionally speaking most plants, including violets, prefer a soil pH around 6. This will allow all of the macro and micro nutrients to be available for uptake. Both warm and cool growing conditions can affect the availability of nutrients such as nitrogen. Ideally it is best to keep the temperature between 68°F to 82°F (20°C to 27°C). Remember that grow lights will produce some heat and keeping a thermometer on your stands will allow you to monitor.
Which fertilizer ratio do you choose from? Garden centers are flooded with endless options. An industry standard is the 3-1-2 or a 1-1-1 ratio. This provides the plants with the essential nutrients that a plant needs to be happy and healthy.
We often forget that most fertilizers deliver the nutrients in a form of a salt. These salts can build up when using larger percentage numbers. Some newer natural based products bypass the salts. However, they use manures, meal-based ingredients and oils. Those come with a pronounced aroma which may or may not be desirable in a home setting.
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Please remember that organic does not mean it is safer and everything is a chemical. More growers have switched over from tap water to reverse osmosis (RO) water. If this is your case you may want to choose a fertilizer that contains a portion of our micronutrients. The RO process does an excellent job removing impurities from the water and in some cases it will remove micronutrients.
When deciding on what to use try to buy the smallest size available. This way if your plants react poorly to the product you are not left with a quart or gallon of something you may never use again. If you decide to switch products try it first on a few plants for three months before introducing to the whole collection. This way you can monitor for any issues.
Finally, if it isn’t broke, don’t fix it.
Choosing the Right Fertilizer
Now that you know why you need fertilizer, let’s talk about how to pick one that works for you. There are about as many fertilizer options as there are species of plants. First, you’ll decide whether you’ll use fertilizer made from man-made or organic materials. Organic materials like manure, fish, and seaweed return nutrients to the soil the same way as in nature, through decay. Synthetic fertilizers are chemically formulated for a specific balance of the big three. Synthetic fertilizer is more popular indoors for two reasons: it’s generally odorless, and you can control the dosage, which is important in small containers.
We recommend looking for a species-specific product. Different plants need different levels of the big three (nitrogen, potassium, and phosphorus). Fertilizer made specifically for African violets is made with their preferred balance in mind.
Fertilizer comes in liquid or solid form. The two most popular types of African violet fertilizer are concentrated liquids and soluble powder. Both are mixed into your plant’s water, delivering a nutrient boost as it takes up water through its roots. You may also encounter granular or tablet-form fertilizer as you start your search; these are better suited for outdoor plants.
Application Methods and Frequency
Mixing plant food into water is a common and efficient method. It’s important, however, to make sure you choose a product that is 100% water-soluble.
There are two routes you can take: fertilize your plant at regular intervals, or every time you water. With the former, the rule of thumb is to fertilize during the growing season. Follow the product instructions (you’ll usually apply between every four to six weeks) and stay on schedule!
You can also opt for a more continuous option. Adding a gentle liquid plant food every time you water or change the reservoir provides a gentle, steady dose of energy to your plant.
Houseplant Pro Tip: There is some debate about whether African violets should be fertilized in the winter since, technically, their growing season can last all year.
Although African violets are easy to please, they can be extremely delicate. When it comes to fertilizer, your biggest risks are burning your plant’s sensitive roots or shocking its system with too much at once. We recommend avoiding products that contain urea, a synthetic chemical widely used in fertilizers to replenish nitrogen.
To encourage frequent blooms, provide consistent care, bright indirect light, and regular fertilizing of African violets with a balanced 2-2-2 fertilizer. African violets prefer evenly moist soil, but avoid overwatering. Water when the top inch of soil feels dry. Fertilize African violets every time you water over the spring and summer during active growth with a liquid fertilizer, such as Perfect Plants African Violet Fertilizer.
Additional Tips for Thriving African Violets
It’s not much of a secret that an African violet will bloom best in good light. Light is one of the primary factors plants need to produce the energy necessary for the production of blossoms. Grown at the window, violets should be within twelve to eighteen inches from the glass. If there is no perfect window, then the grower may wish to supplement the light with a fluorescent light fixture. As a general rule, the lights should be positioned about ten to twelve inches above the leaves and should be turned on for ten to twelve hours a day. Violets under any of the newer energy-efficient lights may need even less hours a day.
If there is too little light, the leaves will usually reach up. Buds dry off when violets are allowed to dry out completely, sometimes before the grower is even aware that they were forming. Water from either the top (under the leaves) or from the bottom pretty thoroughly once a week and drain the excess water promptly. If the climate is a dry one, it helps to supplement with a bit of water halfway through the week to keep the soil from becoming too dry. Along with having even soil moisture, the buds will survive better when there is some humidity in the air.
Starving violets lack the energy to bloom. Many growers have the best success fertilizing once a week with a mild fertilizer designed for African violets. A balanced formula such as a 20-20-20 or one that has slightly more phosphorus, like a 15-20-15 will do well in most growing situations. Read the package!
Healthy violet roots can only grow in potting mixtures that don’t inhibit their development. To encourage better root development, use a potting mix with lots of porosity (the fancy word for fluffy and full of air). A violet mix with plenty of perlite will allow air (and roots) to move freely through the particles of peat moss. Violets in nature do not grow in dirt. Instead, they are found clinging to moss-covered rocks. Growers have found that the best way to duplicate that environment is to keep them in pots that are one-third the diameter of the plant and usually not more than two or three inches deep. Violets tend to bloom when their roots become crowded.
Some violets are simply shy bloomers. They do not have the genetic tendency to bloom freely. Other violets not only bloom often, but the blossom stems carry more buds. Those are the most desirable varieties!
A gently threatened violet is often a blooming violet. The survival of the species instinct causes plants to increase photosynthesis and to try to make seed (by blooming) when there is a possibility of death. Confining roots in small pots or grooming off fading leaves and flowers will all stimulate the development of more flowers. Yet another simple trick is to tap the pot of a non-blooming violet firmly on a hard surface to disturb the roots.
Too little light can cause African violets not to bloom well. They prefer bright, indirect sun. Too little sunlight causes them to stretch for the light and produce few or no flowers; too much sun can burn the leaves. They also need eight hours of darkness every night. Although they need sufficient light in order to produce a flowering hormone known as florigen, florigen does not trigger blooming until it gets dark.
How you water can be a factor, too. African violets prefer to stay evenly moist - ideally, the soil feels like a well-wrung-out sponge. They do not like to dry out completely in between waterings, but they do not like to be sopping wet all the time. Too much water can lead to root rot, while roots start to die in soil that is too dry much of the time.
Your fertilization practices can also impact how well African violets bloom. Unlike plants that grow outdoors, houseplants are totally dependent on the grower to apply sufficient nutrients without overdoing it. The small pots these plants are typically grown in do not maintain a large reserve of nutrients. If you do not fertilize them on a regular basis, they may not have the necessary nutrients to spend on flowers.
You can purchase fertilizers formulated specifically for African violets. You should always use a balanced fertilizer that contains all of the major plant nutrients: nitrogen (N), phosphorus (P), and potassium (K). Nitrogen is important for the growth and development of leaves and stems. Phosphorus is important for healthy roots and flowering. These major nutrients are represented on the fertilizer label by numbers known as the analysis. Typically, fertilizers for flowering plants contain more phosphorus than nitrogen, perhaps an analysis of 8-14-9.
The African Violet Society of America recommends choosing a fertilizer that does not use urea as the nitrogen source because African violets are sensitive to it and it can burn their roots. You can determine if a fertilizer contains urea by looking at the Guaranteed Analysis on the label. It lists the source of the nutrients it contains.
Finally, if you have recently repotted your African violet into a larger pot, the pot may be too big. African violets prefer to be root-bound to bloom well. It is good practice to periodically repot houseplants because the soil should be refreshed periodically. You can often repot the plant into the same pot after cleaning it well, using fresh potting mix.
With proper care, African violets can live for many years-sometimes decades. This is why it is important to properly support them with the care they require.
