Applying fertilizer can be one of the trickiest aspects of houseplant care, especially for slow-growing plants like Peace Lilies. Your Spathiphyllum needs nutrients to grow, but the wrong dose can be worse than no dose at all. We’ll explain how to get it right, and how to choose the best fertilizer for your Peace Lily.
Peace Lilies don’t require huge amounts of fertilizer. We recommend using a liquid formula every 6 weeks during the growing season, starting at ½ strength to be safe. Fertilize less frequently if your Peace Lily is in low light, and stop entirely if it’s dealing with other health problems.
You can also use slow-release fertilizers or organic materials like compost. This article will cover the pros and cons of each option and explain how to avoid giving your Peace Lily too much or too little nutrition. Once you understand the basics, it’s fairly simple to supply your plant with the fertilizer it needs to bloom and grow.
Should You Fertilize Your Peace Lily?
Many people talk about fertilizer like it’s something “extra”, an unnecessary, artificial growth booster. And it’s true that Peace Lilies grow in the wild using just the nutrients in the soil.
However, the soil in the wild is constantly receiving new inputs of nutrition. In the rainforests where Spathiphyllum evolved, decaying scraps of other plants are constantly tumbling into the soil from above. That fallen vegetation decays into a thick mat of organic material that offers plenty of nourishment for a Peace Lily.
An indoor plant doesn’t have access to its natural sources of nutrition. So you’ve got to give it some artificial ones.
Otherwise, your Peace Lily will fail to grow, getting weaker and weaker over time. Without nutrients from fertilizer, it won’t be able to produce healthy new roots, shoots, and leaves. It will be stunted and sickly, growing slowly and rarely – if ever – blooming. Eventually, it will wither away and die.
When to Fertilize a Peace Lily
The first thing to consider when deciding if it’s time to fertilize your Peace Lily is how long it’s been in its pot. If you recently bought it from a garden store or planted it in standard potting soil, you can wait. Store-bought soils usually have a fair amount of nutrition mixed in. It should be safe to wait until the next growing season before adding more.
That brings us to the next point: fertilize only when your Peace Lily is growing. Spathiphyllum plants don’t go fully dormant in the winter. However, unless you live pretty close to the equator, they only get enough light to grow for about half the year. During autumn and winter, they don’t have the energy to do anything useful with fertilizer.
That means any nutrients you add will just sit in the soil in the form of mineral salts. When they reach a high enough concentration, they reduce your Peace Lily’s ability to take in water. High enough salt levels can even damage the roots. So you should fertilize only during the growing season.
It’s also best to stop fertilizing if your Peace Lily is sick. Inexperienced houseplant owners will sometimes add nutrients to an unhealthy plant, thinking it will give it some extra vigor. This is likely to backfire, since a stressed-out plant can’t make proper use of the chemicals you’re adding.
During the growing season, when your Peace Lily is happy and healthy, you should fertilize roughly every six weeks. That’s assuming it’s getting lots of bright, indirect light, which is what a Spathiphyllum prefers.
If you’re keeping it in dim conditions, it will grow more slowly, meaning you should fertilize even less often. 1-3 times per growing season is plenty for a Peace Lily that doesn’t get much light.
What is the Best Fertilizer For a Peace Lily?
Choosing the best Peace Lily fertilizer can be daunting. There’s a dizzying variety of products to pick from, many of them labeled for super-specific purposes. Luckily, a lot of that complication is more about marketing than anything else. We’ll help you break down the choice into a few simple factors.
We’ll begin with the most confusing aspect of choosing a fertilizer: the NPK levels. Those are the three numbers on the label, usually separated by colons or dashes – 20:20:20, 15-30-15, etc. Those numbers represent the percentage of nitrogen, phosphorus, and potassium, in that order.
Leaves have a higher percentage of nitrogen, while flowers and roots contain more phosphorus. That’s why fertilizers high in phosphorus are often labeled as “bloom enhancers” or something similar. Nitrogen-rich formulas may be advertised as promoting foliage growth. So which is more important for Peace Lilies?
The truth is that it doesn’t matter much. Those catchy labels are little more than marketing tricks.
Adding extra phosphorus won’t help your plant produce more flowers. At most, it can make up for a phosphorus shortage that’s preventing it from blooming. The same basic principle holds true for the other nutrients: giving your plant more than the minimum it needs doesn’t help.
Most fertilizers contain more than enough of every nutrient for your Peace Lily. Don’t worry about finding the perfect ratio. You can just stick with a balanced fertilizer that offers roughly equal amounts of N, P, and K.
If you want to get really scientific, pick a product with NPK values that are multiples of 3:1:2. That’s the ratio at which plants naturally absorb these elements.
Fast vs. Slow
Some fertilizers deliver their nutrition in a single big burst. They’re made of compounds that your Peace Lily’s roots can absorb easily. Usually, fertilizers of this kind are sold as liquids or powders that you can dissolve into your plant’s water.
Fast-acting fertilizers are great for precision. You can dilute them to exactly the strength your plant needs. And if you need to correct a severe nutrient shortage in a hurry, a fast-acting formula is perfect.
The risk is that you can overdo it. If you get the dosage wrong, it will hit your Peace Lily’s roots all at once. This may damage the roots, causing a condition known as fertilizer burn. It can leave your Peace Lily severely dehydrated and force it to spend energy repairing its damaged root system.
That’s where slow-acting fertilizers have the advantage. They do just what their name implies – release their payload a little at a time. This makes it much less likely that you’ll harm your Peace Lily by over-fertilizing it.
Slow fertilizers are also simpler to use. You only need to add them once a year – twice at most – and let them break down little by little.
Unfortunately, some slow-release fertilizers can contribute to a pernicious environmental problem: microplastics. Many of these products deliver their nutrients inside tiny capsules of hard resin. They’re porous, which is how the fertilizer gets out, but they aren’t really biodegradable.
So if you use pellet-based fertilizers, don’t just dump the old soil outdoors when you’re done with it. Dispose of it in the garbage. Fertilizer spikes may be a more eco-friendly choice. They’re just solid sticks of nutritious material that dissolve over time.
Synthetic vs. Organic
Up to this point, we’ve been talking mostly about synthetic fertilizers. They’re made by combining chemicals from inorganic sources, like air, minerals, or fossil fuel byproducts. There’s another option, though: fertilizer derived from organic materials like bone meal and seaweed.
That may sound like an obvious call. Organic fertilizers must be better, right? They’re more natural. How could synthetic chemicals be good for your plant?
Actually, your Peace Lily can’t really tell the difference. Organic fertilizers contain large molecules that soil microbes break down into chemicals your plant’s roots can absorb. But by the time your Spathiphyllum gobbles them up, the nutrients are identical to the ones in synthetic fertilizer.
The real advantages of organic fertilizer are:
- Soil structure. Organic fertilizers feed the helpful bacteria in your soil. They help keep it aerated and improve drainage, which is good for your Peace Lily. Of course, you probably won’t be building up houseplant soil over the long term like you would garden soil. Most Peace Lily owners repot their plant every few years.
- Slow action. The gradual breakdown of organic fertilizers acts a lot like the slow-release capsules in some synthetic fertilizers. It provides the same protection against fertilizer burn.
- Environmental benefits. Organic fertilizers tend to be less processed than synthetic versions. That means their production doesn’t consume as much energy or create as much pollution.
There are some downsides, too. The slower speed of organic fertilizers makes them less useful for correcting a dire nutrient shortage. And since they’re made from decomposing bits of living things, many have a pretty pungent smell! Give a little thought to ventilation before applying these products.
Are Banana Peels Good For Peace Lilies? How About Coffee Grounds?
The internet is full of tips on how to use your kitchen scraps to fertilize your houseplants. In particular, you can find lots of recommendations for banana peels and coffee grounds. Is there anything to this advice?
The answer is a cautious yes. Like all organic materials, these substances contain some of the nutrients your Peace Lily needs. As they decay, they will slowly add fertility to the soil.
However, we do need to correct some misconceptions and warn you of some drawbacks.
First of all, these materials have a pretty low nutrient value by weight when compared to most commercial fertilizers. Many people think banana peels are turbo-charged with potassium or coffee grounds offer a huge burst of nitrogen. In reality, they’re both fairly weak, slow-acting fertilizers.
Plus, you’re talking about leaving food waste in an uncovered planter to rot. That can attract pests ranging from fruit flies to roaches, or create a breeding ground for fungus. And too much organic material will make your potting mix very water-retentive. That’s generally bad for Peace Lilies, which are vulnerable to root rot.
If you’re going to use kitchen scraps on your Peace Lilies, do it sparingly. Limit yourself to a light sprinkling of coffee grounds or a few shreds of banana peel at a time. And avoid using coffee on young plants. Some studies have shown that it can inhibit the growth of seedlings.
The best way to put your food waste to work in the soil is to compost it. Letting microbes chew up plant scraps does away with the downsides we mentioned above.
Our Favorite Peace Lily Fertilizers
We recommend a liquid fertilizer for your Peace Lily. Since you can dilute them, they’re often very cost-effective – one bottle can last a long time. They also allow you to raise or lower the dosage depending on your plant’s needs.
Jack’s Classic All Purpose is a strong fertilizer with an even NPK balance. A little bit of this powder will go a long way. If you prefer to use a nutrient ratio that mimics what plants use in nature, try Dyna-Gro Foliage Pro. And if you want to go organic, Aquatic Arts Indoor Plant Food is an excellent choice.
Note that whatever fertilizer you choose should work pretty well for all your houseplants. The idea that certain plants need super-specific NPK ratios is another sales gimmick.
How to Fertilize Your Peace Lily
The first time you use liquid fertilizer on your Peace Lily, dilute it a bit more than the instructions recommend. You can always add more later, but you can’t undo the damage from using too much. Go with ½ the recommended dosage, or ¼ if your Peace Lily is in low light.
Mix it up in a bucket or watering can until the fertilizer is thoroughly dissolved. Then water just as you normally would, soaking the soil all the way through so that some liquid is draining out the bottom.
Over the next few days, watch out for indicators that you’ve over-fertilized. If your Peace Lily’s leaves get brown and crispy at the edges, or start rapidly turning yellow or brown, you’ve probably gone too far.
If you don’t see any danger signs, give your Peace Lily another round of fertilizer in about 6 weeks. Repeat this a few more times.
Is your plant now producing healthy growth and vibrant blooms? Then you can assume the current dose is all it needs. If it still seems slow or stunted, you can start increasing the concentration little by little.
Does Your Peace Lily Need More Fertilizer?
Spotting when a Peace Lily is under-fertilized takes a bit of skill. Your plant might not look distressed even though it’s falling short of its growth potential.
Peace Lilies don’t exactly grow like weeds, but they normally get 3-5 inches taller each growing season. If your plant appears to be stuck at the same height and isn’t generating new leaves, it could be low on fertilizer.
Note: rule out every other possible cause for slow growth before upping your fertilizer dose. Otherwise, you’ll do more harm than good. The following problems are all more likely to stunt your Peace Lily than lack of nutrients:
- Low light
- Repeated under-watering
- No room to grow in the pot
More drastic signs include thin, weak stems, pale foliage, and a failure to bloom. Shortages of certain elements cause leaves to get shriveled or twisted, while others cause various kinds of discoloration. Here’s a handy chart that shows the effects of several common plant nutrient deficiencies.
How to Save an Over-Fertilized Peace Lily
If you slipped up and gave your Peace Lily too much fertilizer, it’s not necessarily a death sentence. You can often limit the damage with a soil flush.
That basically means an extra-heavy watering. If you run a large volume of water through the soil – 4-6 times the volume of the pot – it should carry most of the mineral salts with it. Distilled, lukewarm water works best. Pour slowly but steadily, letting the water permeate the soil and run out the pot’s drainage holes.
You can use this as a preventative measure too. If you fertilize your Peace Lily regularly, it’s best to give it a soil flush every 1-2 months. This helps keep nutrients from building up to harmful levels in the soil.
Fertilizing your Peace Lily requires a balanced approach, but it’s not as complicated as it might seem at first. Just remember to start with low doses, and apply them only when your plant has everything else it needs to grow. You’ll soon develop an instinct for when and how to supplement your Spathiphyllum’s diet.