When I first started collecting houseplants, I never thought about fertilizing them. In my mind, they could live on forever in the same pot with just a bit of water every now and then. But since then, I’ve learned so much more about plants and one of the key ingredients to keeping healthy houseplants is supplementing them with fertilizer. So let’s talk about fertilizer and ZZ Plants. What kind do they like and how often should it be applied?
What fertilizer is best for ZZ Plants? ZZs should be fertilized with a balanced 10-10-10 or 20-20-20 fertilizer once a month during their growing season from spring through fall. Always dilute your houseplant fertilizer to half strength as fertilizer that is too strong can damage your ZZ Plant foliage and root system.
Fertilizing seems simple enough, and it is, if you know what you’re looking for. Once you start down the fertilizer rabbit hole you’ll find there are a ton of different options and methods for feeding your ZZ Plants. I’m going to go over what fertilizer is, how it helps your plants and give you my suggestions for the best options for your ZZ.
Why Fertilizing ZZ Plants is Important
Your first two questions are probably: Do ZZ Plants really need to be fertilized and why does it matter? The quick answer is this – if you want them to live happy and healthy for many, many years, ZZs need fertilizing.
In nature, plants have access to a constant flow of nutrients. They are able to extend out their roots and find the things they need in their natural environments, as well as absorb rain water, which is full of natural nutrients and minerals.
Indoors, houseplants are restricted to the limited number of nutrients available to them in their small containers. No amount of stretching or reaching of roots will get them access to anything else. For this reason, they need our help to thrive.
Pre-made potting soil is fortified with nutrients. When we place our plants into these store bought blends, they are able to absorb those nutrients from the soil. Over the course of three months to a year, depending on the size of plant and container, your ZZ Plant will consume all of the nutrients available to it in potting soil, leaving it sitting in depleted soil. This is where fertilizer comes into play.
There is a common misconception that fertilizer is food for plants. This isn’t the case. Plants create their own food from water, CO2 and sunlight through the photosynthesis process.
Fertilizer is more like the vitamins that help our plants grow big and strong for years to come. They aren’t needed to feed your plant, but the different macro and micro ingredients give your ZZ the nutrients they need for healthy stems, roots, leaves and more.
What Is In Fertilizer?
Houseplant fertilizer is made up of a number of ingredients. Those ingredients are usually categorized as macronutrients and micronutrients. Macro or micro refers to the amount of that nutrient that plants need to be healthy, not to the importance of the nutrient to your plant.
The three primary macronutrient ingredients in fertilizers are nitrogen, phosphorus, and potassium. They are required for healthy growth in the largest quantities by plants. I’ll discuss each of these ingredients and their benefits more in the following section. The most common secondary macronutrients include calcium, magnesium, and sulfur. Plants need smaller amounts of these items.
Micronutrients are just as important to plants, but they are needed in even smaller quantities. Micronutrients found in fertilizers are iron, zinc, manganese, copper, boron, molybdenum, and chlorine. Compared to macronutrients, only a very small amount of any of these nutrients is included in fertilizer mixtures.
N-P-K Ratios
If you’ve looked into fertilizer at all, you have probably noticed the three numbers on the front of most bottles. These numbers (usually formatted like this: 6-10-4) guide us to know which plants this fertilizer has been formulated for based on the composition.
N, P, and K stand for nitrogen, phosphorus, and potassium. The numbers tell us what percentage of the fertilizer mixture is composed of each of these primary macronutrients. A fertilizer that is 10-10-10 has 10% nitrogen, 10% phosphorus and 10% potassium, while a 12-6-8 mixture has 12% nitrogen, 6% phosphorus and 8% potassium.
The type of plant you want to fertilize will determine the nutrient ratio you’ll need to purchase. The fertilizer you would use for your front yard is different from that which is best for growing spicy pepper plants. Even different types of houseplants need different ratios of ingredients, as each macronutrient is helpful in different processes for your plant.
The first primary macronutrient is always nitrogen. Nitrogen is important for the photosynthesis process of plants and helps to promote leafy, green growth on the plant (think stems and leaves).
Phosphorus is the next primary macronutrient and is essential to creating healthy root structures. It also encourages flower blooms so flowering plants often require higher amounts of phosphorus.
Potassium is represented by K in N-P-K, which is its elemental symbol on the periodic table. Potassium is the macronutrient that helps plants to become hardy and able to tolerate less than ideal conditions. Potassium also helps regulate water uptake and improves a plant’s ability to fight off disease.
You’ll see fertilizer formulas with different levels of each nutrient, depending on what it is trying to accomplish. For example, many grass feeds are mainly nitrogen. Commercial “blooming” mixes for annuals and edibles typically punch up the phosphorus to encourage more flowers.
In the case of a ZZ Plant, which has a lot of leafy green growth and a root system easily upset by improper watering, we opt for a balanced mix. We want to make sure all aspects of the plant are benefiting from the feed we provide it.
The Risk of Fertilizing
When it comes to fertilizing, too much of a good thing is a very real problem. Too much fertilizer can lead to leaf scorch and yellow or brown spots on your ZZ’s foliage as well as damage to the roots system. This often shows up a day or two after you fertilize but can take as long as a few weeks before it starts to show.
For this reason, I always always always dilute my fertilizer to half the recommended strength before pouring it onto my houseplants. If you have multiple ZZs you may want to test fertilizer on one plant one month, before applying to all the others.
If you start to see any of the indicators of fertilizer burn on your ZZ Plant, flush the soil as quickly as possible. To do so, run your ZZ under water and let the water flow from the drainage hole for a few minutes. Remember to let it dry out completely before watering again.
The Three Types of Fertilizers
When searching for the perfect houseplant fertilizer, you will come across three options: liquid, granular and slow release. Each type of fertilizer has its own pros and cons. For ZZ Plants, I prefer to use liquid fertilizer as I can easily dilute the strength of it.
Liquid fertilizer comes in two forms: powder or concentrated liquid. In either case, the fertilizer is mixed with water and poured onto your houseplants. Because you mix it yourself, liquid fertilizer gives you the most control over how much you give to your ZZ.
Granular fertilizers are pellets that you put on top of your pot and either water or work into the soil. These types of fertilizers are great for outdoor gardens but I find them to be less helpful for houseplants.
Slow release fertilizers come in the form of pellets or spikes that you place into your plant’s soil. As you water your plant over the next few months, fertilizer is dispersed into the planter to feed your plant. These formulas cannot be altered or diluted easily, so again, I prefer a liquid fertilizer for ZZ Plants.
Organic Fertilizer and Synthetic Fertilizer
There are two more classifications when it comes to fertilizers: organic and synthetic. These are classifications that you will see in conjunction with the type of fertilizer you purchase. For example, I like to use a synthetic, liquid, 20-20-20 fertilizer on my ZZ Plants.
When referring to fertilizer, organic means that it has been created with natural materials (with no indication to pesticides or other things we think of when we think of the word “organic”.) Because it is composed of only natural ingredients, it is generally more expensive than the synthetic alternative.
The components of natural fertilizers have usually not been processed and are therefore not as easy for your plant to immediately uptake. This type of fertilizer usually breaks down in the soil and treats the soil more than the plant itself.
Synthetic fertilizer is made of ground up minerals and chemicals and is commonly referred to as “the blue stuff”. Because it is chemically formulated it can be produced with near-exact amounts of nutrients for plants.
All components in synthetic fertilizers have already been processed and are ready for immediate uptake by your plants. Chemical fertilizers are more cost-effective than organic fertilizers and are often more concentrated – meaning you’ll want to dilute them before using them on houseplants.
When it comes to fertilizing a garden or herbs, I personally prefer to use the natural, organic options. However, with plants like ZZs and other indoor houseplants, I’ve often use the synthetic versions as well.
My Recommended Houseplant Fertilizers for ZZs
If you’re looking for a specific recommendation, and less of the scientific information surrounding it, I’m imagining you’ve scrolled to this point in the article. I get it! Sometimes I want to know all the information behind the best choices to be made, and sometimes I just want someone to tell me what to buy.
I am going to recommend two of the most common houseplant fertilizers that I use on my own plants, ZZs included. One is organic and one is synthetic. The synthetic version is cheaper than the organic, but if you feel strongly towards using natural ingredients, it is just as effective as the other.
Jack’s Classic All Purpose Fertilizer is far and away my favorite product. Because it is a 20-20-20 mixture, I dilute it to quarter strength before watering my ZZs with it each month. That means I only use ¼ tsp per gallon of water instead of the recommended 1 tsp.
I’ve had the same container of Jack’s fertilizer for a long time now and I use it on most of my indoor plants each month. If you’re looking for the most bang for your buck, go with Jacks.
The runner up in my book is Espoma Organic Indoor Fertilizer. This one has a 2-2-2 ratio and is both natural and well-balanced. For this, I dilute to ½ strength by adding one dose of 7ml to 2 quarts of water (or half of a gallon) and water my ZZs with it once per month.
The bottle is quite a bit smaller and certainly doesn’t last as long. However, if you’re looking for a non-stinky, organic fertilizer, I like Espoma.
How to Fertilize ZZ Plants
Now that you know which fertilizer to purchase, you’ve come to the time where you actually need to feed your plant. Remember, no matter which fertilizer you choose (whether one of my suggestions or otherwise) you should dilute the mixture to half strength. Fertilizer burn is no fun to deal with and I always try to tell myself that I can add more fertilizer, but I cannot take it away. Take it easy.
To mix your fertilizer, follow the instructions provided on the packaging. All fertilizers will tell you how much liquid or powder should be mixed with how much water. I generally use tap water to mix with my fertilizer for my ZZs, but for more sensitive plants you may want to consider using distilled.
Generally, I mix up my fertilizer in an old milk jug as most will tell you how much fertilizer you need per gallon of water. Then I simply put the cap back on and give it a good shake to mix it fully before pouring it into my ZZ soil.
When it is time to fertilize your ZZ each month, it is important that your plant’s soil is not completely dry. Soil must be damp for the fertilizer to reach all the way to the roots, which is necessary for absorption.
I like to fertilize my ZZ Plants the day after I water them. ZZs do not like excess water but I find that watering the second day for fertilizing does not hurt my plants if I only do it once per month.
The fertilizer mixture should be poured over your plant until it runs out of the drainage hole. This will ensure that enough fertilizer will reach the roots to be absorbed by your ZZ.
How Often to Fertilize ZZs
I only fertilize my ZZ Plants once every month or two from spring through fall. During the winter, house plants, including ZZs, go into their dormant phase where growth is greatly slowed. When plants are dormant they cannot uptake nutrients as quickly and are more likely to be burned by the fertilizer. I never fertilize in the winter.
If you are feeling nervous about fertilizing your plant, take it easy. You do not have to feed your plant every single month for it to be effective. Start slow. Feed your plant now and then wait two or three months before you do it again. This will give you plenty of time to watch for signs of burn and remedy the issue.
How To Make a ZZ Plant Grow Faster
When it comes to speed of growth, ZZs definitely fall on the slow side. While plants like Monsteras or Rubber Trees may be putting out new growth seemingly overnight, ZZs are slow and steady, like the tortoise of the houseplant world.
Even though they are not known for quick growth, there are a few things you can do to encourage and speed them up along their way. Fertilizing plants is an excellent option for that. But remember, more fertilizer doesn’t always mean more growth. Too much fertilizer will burn your plant’s foliage and root system, stunting growth instead of fostering it.
Other things that will encourage new growth are providing the plant with more bright, indirect light and transplanting it to a new container once every two years. For more tips to get your ZZ to grow more quickly, read this article. But remember, ZZs grow on their own time table. Don’t force anything and they’ll be with you for years to come.