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Are you struggling with a straggly leaved pothos, wondering if the leaves will ever get bigger? They will, but not without your help.
If the conditions are right, a pothos plant can grow by up to a foot in a month during the growing season.
Indoors, that would be miraculous as that growth rate is typical for a pothos in their natural tropical habitat. Not indoors. Growth will be slightly slower, but it can still be a fast-growing plant provided you give it favorable growing conditions. High humidity, warm temperatures, and lots of bright indirect sunlight.
Light is the key to getting everything right for a pothos plant indoors.
Why the Need for Light?
Because it is essential for photosynthesis. The pothos plant is an aroid that belongs to the Arum family, sometimes referred to as the Araceae genus.
These plants are grown for foliage, and depending on the species of pothos you grow, it can have variegated leaves with patterned designs such as green leaves with yellow veins.
Lose the light, the patterns disappear.
Aroids always favor warm and wet climates. That is only pertaining to the room atmosphere and definitely not the soil. The soil needs to dry out almost completely between watering to prevent soil-borne diseases contributing to root rot.
One way to mitigate problems with overwatering and underwatering is to work with an aroid soil mix. The soil for indoor pothos ought to be fast-draining but also contain chunky materials to help improve aeration around the roots.
Without sufficient air circulation happening in the soil, oxygenation decreases and the effect of that is seen above the soil line in the form of smaller leaves, drooping, and straggly vines struggling for survival.
Plants absolute need carbon dioxide for survival. Without it, they can’t photosynthesize, and the result of that is they cannot produce the food they need for optimal growth. The more a plant can photosynthesize, the healthier the leaves will be.
The surest way to increase the size of pothos leaves is to increase the amount of available light it has access to. You do not want the leaves to be crowded so much that some leaves get the light blocked by larger leaves because every leaf on a pothos plant uses photosynthesis.
If a small leaf is being overshadowed by a larger leaf, the shaded leaf will not grow much bigger. Prune off leaves that are being crowded.
Something to be weary of is that you have two choices with pothos plants, and you do need to pick one method. You can make a pothos fuller by propagating the plants and grouping multiple cuttings together, or you can grow them with the sole intent of getting bigger leaves.
You will struggle to get big leaves on a bushy pothos because by its nature, most of the lower leaves will be in the shade of the bigger leaves above it.
Addressing the Issue of Shrinking Leaves on Pothos Plants
New leaves will always grow in smaller and may take some time to mature into a decent size. Under the right conditions, they should be increasing in size every month between May and December.
A respectable size for the leaves on an indoor pothos is 8-inches. 4-inch leaves is on the small side. 8-inches are large. 12-inch leaves are what these are capable of reaching in their natural habitat outdoors in the tropics.
If you find the leaves on your pothos shrinking, it will be because something that the plant is used to has changed. Most likely, the soil conditions.
Fast draining soils, particularly aroid mixes, contain organic material. These will break down over time, which is the intent, because the organic material such as orchid bark release nutrients into the soil, allowing the roots absorb extra nutrients.
The immediate benefit of bark chips is the chunkiness of them because it increases aeration and that prevents the soil from compacting, such as immediately after watering.
Over time, as the bark decomposes, there will be less oxygenation happening in the soil because of compaction. The plant will show signs of watering problems, such as yellowing leaves, and wilting.
The fix is to repot with a fresh potting medium. Generally, you should expect to be repotting pothos every couple of years.
However, if you fertilize a pothos too frequently, the reaction will be faster degradation of the potting mix.
Pothos do not need heavy fertilizing. A diluted feed of a balanced fertilizer, such as a 20-20-20 or 10-10-10 fertilizer once weekly is sufficient. Until it is not.
There will come a point when the plant responds to a lack of nitrogen by putting out small leaves that will not grow, or grow much slower than older leaves did.
When you feel your pothos leaves are shrinking, or just not putting on the size you would expect, go higher on the nitrogen and lower on everything else.
Nitrogen is what pothos needs for the greenery in their leaves from the chlorophyll. The more chlorophyll there is in the leaves, the more the plant can photosynthesize. That is when you get the bigger leaves on pothos.
In essence, to make pothos leaves bigger, it is a two-pronged process.
Step 1: Increase the nitrogen content in the fertilizer, which will improve the chlorophyll in the leaves. The greener the leaves are from the higher nitrogen content; the more photosynthesis occurs.
Switch from a balanced all-purpose fertilizer (i.e: 10-10-10) to a 19-16-12 fertilizer or similar. Anything with the first number higher. If you weren’t aware, those numbers are known as NPK = Nitrogen, Phosphorous, Potassium – in that order.
Step 2: Increase light. Pothos need lots of bright but indirect sunlight for the best growth. And the pot may need rotated to ensure all the leaves get access to light.
The alternative in low and even moderately lit environments that aren’t sufficient, is to supplement with artificial light sources.
The cheapest to run are LED grow lights and the sweet spot for photosynthesis is 460 nm (nanometers). It falls on the blue light wavelength which is suitable for growth.
With pothos, growth is all you need for photosynthesis.
The Other Crucial Factors Are Humidity and Temperature
Warm and wet are what pothos crave in their growing atmosphere. For humidity, the sweet range is between 50% and 70%. That is high! There’s no way you would be comfortable with that environment.
The Environmental Protection Agency recommend a relative humidity (RH) between 30% and 50% as a precaution against mold growth in your home. Never exceed 60% room humidity.
For indoor gardeners growing plants that prefer the tropics, it is a challenge.
How to Raise Humidity Just Enough for Your Plants:
Use a humidity tray under the pot, have a plant humidifier set to auto mist periodically throughout the day, or manually mist the plant.
Brown leaf tips on a pothos plant is how to tell the humidity is too low.
Temperatures Are Paramount to Get Right (and maintain)
High humidity takes care of keeping the leaves on the plant wet. It does nothing for the air surrounding the plant.
For that, you need the correct temperature range. 70-90 ºF (21-32 ºC). The higher the better.
This again, can tie back to your lighting setup, as it is unlikely you will want to heat your room to the extreme side. LED lights do produce heat. Not as intensive as incandescent bulbs, nor is it direct, but rather they produce convection heat that is reflected from the housing unit.
The closer the light fixture is to the plant, the warmer the temperature will be.
When you see that the temperature requirements for any plant is high, remember it is the leaf temperature and not the room temperature.
So long as you can raise the leaf temperature above 70 ºF (21 ºC), a pothos plant will be able to produce bigger leaves. The simplest way to measure the leaf temperature is with a laser or infrared (IR) thermometer.
Warm, bright, and high humidity with fast-draining soil are the key components to make pothos leaves bigger.