In the world of houseplants, it’s not uncommon to hear that a plant is tough to care for when its requirements are actually quite basic.
This is also true of the Philodendron (fil-oh-DEN-dron) genus, which can handle a lot of neglect when its basic needs are met.
One of these needs for all types of Philodendron is fertilizer, which is always more necessary for indoor plants than outdoors.
Outside, nature ensures the soil is replenished constantly, but fertilizer is often the only way to ensure a plant’s health for a potted plant.
What Is The Best Fertilizer For Philodendron Plants?
A 20-20-20 liquid houseplant fertilizer tends to be the best for almost all philodendrons.
Pay attention to potential shifts in soil pH or other complications, especially if you’re making your own fertilizer.
Warning: Not All Philodendrons Are Equal!
There are hundreds of philodendron species and thousands of cultivars.
While the vast majority have similar care instructions, there are always exceptions to the rule.
Keep this in mind when using any general guide on philodendron care, and be sure to adjust any care requirements as needed for your specific plant.
What Philodendrons Need Most?
As rainforest-based epiphytes, philodendrons like rich, humusy soil, and the forest constantly replenishes these soil nutrients.
Since your potted Philo doesn’t have the benefit of nature, you’ll have to fill in.
This means you should provide both macro and micronutrients via fertilizer.
Liquid fertilizers work best, followed by water-soluble, and lastly, slow-release.
The macronutrients are the following:
- NPK (nitrogen, phosphorus, and potassium) rating of the fertilizer
Additionally, you’ll need to provide micronutrients (trace minerals) such as:
Choosing A Commercial Fertilizer
The majority of philodendrons require a balanced 20-20-20 fertilizer.
Phosphorus (the middle number) is less important because philodendrons rarely bloom domestically, although it’s still crucial for the plant’s general health.
Note that performing a soil test on your garden or a new bag of potting mix can help you fine-tune the NPK ratio, making up for deficient nutrients while cutting back on those the soil already has in abundance.
When possible, aim for a liquid formula, as slow-release fertilizers don’t release the contained nutrients at the same rates.
Making Homemade Fertilizer
Homemade fertilizers can be a little tricky, as any given ingredient may have different nutrition levels each time you use it.
However, some ingredients work really well and provide extra benefits.
Your homemade fertilizer will likely have a compost base, preferably from a worm-filled compost pile.
However, manure teas can also work wonders.
Used coffee grounds are an excellent source of nitrates and contain potassium and phosphorus.
Oddly enough, the plants won’t be getting any nitrogen from the grounds themselves.
Instead, beneficial microorganisms will consume the coffee nitrates without taking valuable nitrogen from the soil itself.
You can also throw the grounds into your compost pile.
When using coffee grounds, you’ll need an organic component—the used filter will do perfectly, but you can also use crushed leaves.
Another useful kitchen ingredient, your leftover eggshells, is a prime calcium source.
One of the best ways to use them is to make hard-boiled eggs, saving the water for the next time your philodendron becomes thirsty.
The boiled shells can then be crushed (raw shells will also work) and mixed into the soil.
By lightly crushing the shells and sprinkling them on top of the soil, you can not only provide nutrients but will kill any snails or slugs that might attack a Philo (or other plants) in your garden or potted outdoors.
Used Aquarium Water
If you have a freshwater aquarium and use snails or other natural algae feeders instead of chemicals, you’ve got a surprisingly rich food source on your hands.
Not only does the water contain organic matter, but there are plenty of nitrates present from the fish poop.
Signs Of Malnutrition
When you give your plant too much or too little to eat, you can expect it to let you know.
Some common signs of malnutrition are:
- Brown or yellow along the leaf margins
- Burn marks on the plant’s stem or where it touches the soil
- Fragile root systems (including aerial roots)
- Leaf drop
- Leggy growth
- Sluggish growth
- Soil surface appears crusty
- Young leaves become limp and yellow
When you see any of these symptoms, it’s important to adjust how often you feed the plant and may even need to do an emergency soil change if the symptoms are bad enough.
When To Fertilize?
Depending on your plant and the fertilizer you’ve picked, it’s likely you’ll need to fertilize 1 to 2 times per month in spring and summer.
Don’t feed your Philo in fall or winter, even if it appears evergreen unless the cultivar specifically needs a different feeding schedule.
It’s usually best to start off using a commercial liquid houseplant fertilizer monthly and adjust the frequency if you see symptoms of malnutrition.