Not all popular indoor plants come from Central and South America, even though it often seems that way.
A perfect example is the West-African fiddle-leaf fig (Ficus lyrata), which can reach nearly 50’ feet tall outdoors but is more often grown as a houseplant due to its intolerance of temperatures below 50° degrees Fahrenheit.
However, there are a few key factors to keep in mind when growing a fiddle-leaf, as the plant won’t reach its full potential in US climates.
One of these factors is proper fertilization, which will help ensure you have a full, healthy plant for many years.
What Is The Best Fertilizer For Fiddle Leaf Figs Indoors?
Fiddle-leaf figs have large foliage, so proper fertilization can be essential to keeping your plant happy and healthy.
Choosing the right fertilizer goes beyond simply grabbing something with the proper NPK ratios.
The Best NPK Ratio
When choosing a fertilizer, the first thing most people consider is the NPK ratio.
This is important because of these three nutrients:
- Nitrogen
- Phosphorus
- Potassium
These nutrients affect almost every aspect of a plant’s growth, although each of the three also has a key benefit and drawback.
Nitrogen is essential for healthy foliage, but too much can become toxic to the plant.
Phosphorus primarily boosts blooms but somewhat benefits foliage growth in non-flowering plants, although too much will result in a potassium deficiency.
Potassium affects plants much like people, essential for strong stems and a healthy immune system, but it’s a very fragile nutrient that easily leeches out of the soil.
That said, fiddle-leaf figs need a 3-1-2 NPK ratio.
Looking at what these nutrients do, it’s easy to see why this ratio is essential, and you can use any fertilizer in multiple ratios (such as 6-2-4) as long as you dilute it properly.
You’ll also want to ensure the fertilizer provides macro and micronutrients such as:
- Boron
- Calcium
- Copper
- Sulfur
Fiddle-leaf figs are more tolerant of chlorine than most plants, and fertilizers containing this chemical will be fine.
However, you should still avoid tap water as it contains harmful mineral salts and flouride.
Soil pH And Fertilizer
Let’s pause for a moment to talk about soil pH.
This isn’t normally discussed when discussing fertilizers, but it does have an effect.
PH levels are divided into a point system, with every 5-10 decimal point equating to a different level.
Anything below 4.5 is considered highly acidic (think lemons, stomach acid, etc.) and will outright kill most plants.
Meanwhile, anything above 9.1 is considered powerful alkaline (such as ammonia and the mineral lime).
Most plants, including fiddle-leaf figs, grow in a pH range of slightly acid (6.1 to 6.5) to neutral (6.6 to 7.3).
But what does this have to do with fertilizer?
If a plant is in soil that lacks the proper pH range, that plant’s roots won’t be able to absorb and process nutrients efficiently.
Thus, if you allow your fiddle-leaf fig’s soil to drop below 6.0 or get higher than 7.0, it may show signs of malnutrition.
If you know you’re using the proper amount of fertilizer, try to do a pH test on the soil before you change dosages, or you could end up doing more harm than good.
Why Is Slow-Release Bad?
Another important consideration when choosing fertilizer is using a liquid-soluble or slow-release formula.
A large percentage of sites out there suggest using slow-release granules, but this is actually bad for your plant in the long run.
In reality, these sites forget to mention that each nutrient has a different speed for breaking down, so at any given time, your fig is getting a burst of one nutrient while getting little to none of another.
Of course, the big marketing ploy for these fertilizers is that they save time, but they actually end up causing you more work because you’ll have to supplement the plant to make up for these imbalances.
The Advantages Of Liquid-Soluble Formulas
Sure, you have to provide liquid-soluble fertilizers more often, but you won’t even notice.
How is that possible?
Liquid fertilizers are diluted in water, which means you’ll be using the fertilizer in place of a normal watering session.
Additionally, the nutrients are dissolved in water, which means they absorb the soil more quickly and make it easier for the plant’s roots to absorb and process.
A third advantage is that you can dilute these fertilizers to different strengths as needed, so it’s easy to adjust if your pant is getting too much or too little.
This can be an even greater bonus if you like to make fertilizer teas, such as manure or eggshell tea, which can be great for supplementing specific nutrients.
Finally, liquid fertilizers have a much lower risk of causing chemical burns to your plants as long as you don’t get any directly on the plant itself.
How To Fertilize Your Fiddle-Leaf Fig?
How often you fertilize can depend on the brand itself, but there are some basic rules you can follow, adjusting as needed.
Most liquid-soluble formulas can be given once per month during spring and summer.
Be sure to cut back as temperatures begin to cool off in the fall, as the plant will be going dormant so that it won’t be eating, and any added fertilizer may toxify the soil.
Always follow the instructions on the package since each brand can have slightly different qualities.
You can constantly adjust the dosage as needed for a particular plant.
Note that a couple of fiddle-leaf fig-specific plant foods are meant to be used during every watering (during the growing season).
If you aren’t already using the soak and dry method of watering, now’s a good time to switch, as this method prevents over and underwatering and ensures you get just the right amount of fertilizer.
Begin by pouring slowly and evenly so that the soil absorbs any water at the same rate you’re pouring it.
Work your way around the pot, getting all the soil but ensuring you don’t get the plant itself wet.
Continue watering until you either see moisture seeping from the pot’s drainage holes or the soil is no longer absorbing at the same rate you’re pouring.