Not enough information to diagnose with any certainty. Main causes of leaf loss include: over/under-watering, change in light levels - especially from bright to dim, diseased roots, low fertility - especially deficiencies of nutrients that are considered mobile in the plant.

By the way the shadows fall, it looks like the leaves being shed are being shaded by foliage between the affected leaves and the light source. If it's not over/under-watering, I'd say that's a likely suspect.

Do you fertilize? If yes, tell us a bit about that, please.

Al

Hi Al! Thanks for the quick response. We don’t currently fertilize, we’ve had the plant for about 2 years.

The light could definitely be a cause! There is a north facing window outside of the photo and the yellow leaves are furthest from the light. We moved in September so this is its first winter in this spot.

FYI - some nutrients (N, P, K, Mg, et al) can move about inside the plant. Others are considered immobile or nearly so. The immobile nutrients, like Ca, must be available in the soil and in the nutrient stream at all times for normal growth. When there is a deficiency of any mobile nutrient, the plant will rob the nutrient in short supply from other plant parts to provide what's needed for new growth. Normally, the plant robs these nutrients from older foliage, or foliage closer to the stem/trunk in plants with branching structures. After the nutrients are extracted from the sacrifice leaves, they are shed. We don't know if it's light or fertility that's causing your plant's leaf loss, but there is no doubt that 2 years w/o fertilizer virtually insures more than one issue related to nutrition is in play.

I'd say a good plan would include A) trying to fix the low light issue, B) get started on a fertilizer regimen that makes use of a high quality soluble synthetic fertilizer (like Foliage-Pro 9-3-6), C) get your watering under control by using a 'tell' to 'tell' you when it's time to water. If the pot the plant is in was plastic, you could easily tell when it needs water by hefting it to test its weight, but that doesn't work as well for clay pots - which ARE the best (conventional) choice, IMO.

Using a 'tell'

Over-watering saps vitality and is one of the most common plant assassins, so learning to avoid it is worth the small effort. Plants make and store their own energy source – photosynthate - (sugar/glucose). Functioning roots need energy to drive their metabolic processes, and in order to get it, they use oxygen to burn (oxidize) their food. From this, we can see that terrestrial plants need air (oxygen) in the soil to drive root function. Many off-the-shelf soils hold too much water and not enough air to support good root health, which is a prerequisite to a healthy plant. Watering in small sips leads to a build-up of dissolved solids (salts) in the soil, which limits a plant's ability to absorb water – so watering in sips simply moves us to the other horn of a dilemma. It creates another problem that requires resolution. Better, would be to simply adopt a soil that drains well enough to allow watering to beyond the saturation point, so we're flushing the soil of accumulating dissolved solids whenever we water; this, w/o the plant being forced to pay a tax in the form of reduced vitality, due to prolong periods of soil saturation. Sometimes, though, that's not a course we can immediately steer, which makes controlling how often we water a very important factor.

In many cases, we can judge whether or not a planting needs watering by hefting the pot. This is especially true if the pot is made from light material, like plastic, but doesn't work (as) well when the pot is made from heavier material, like clay, or when the size/weight of the pot precludes grabbing it with one hand to judge its weight and gauge the need for water.

Fingers stuck an inch or two into the soil work ok for shallow pots, but not for deep pots. Deep pots might have 3 or more inches of soil that feels totally dry, while the lower several inches of the soil is 100% saturated. Obviously, the lack of oxygen in the root zone situation can wreak havoc with root health and cause the loss of a very notable measure of your plant's potential. Inexpensive watering meters don't even measure moisture levels, they measure electrical conductivity. Clean the tip and insert it into a cup of distilled water and witness the fact it reads 'DRY'.

One of the most reliable methods of checking a planting's need for water is using a 'tell'. You can use a bamboo skewer in a pinch, but a wooden dowel rod of about 5/16” (75-85mm) would work better. They usually come 48” (120cm) long and can usually be cut in half and serve as a pair. Sharpen all 4 ends in a pencil sharpener and slightly blunt the tip so it's about the diameter of the head on a straight pin. Push the wooden tell deep into the soil. Don't worry, it won't harm the root system. If the plant is quite root-bound, you might need to try several places until you find one where you can push it all the way to the pot's bottom. Leave it a few seconds, then withdraw it and inspect the tip for moisture. For most plantings, withhold water until the tell comes out dry or nearly so. If you see signs of wilting, adjust the interval between waterings so drought stress isn't a recurring issue.

You might find this to be helpful.

Al

Yellowing leaves on pothos is typical in winter - old leaves will eventually yellow and fall off on their own. Just remove the yellowing leaves and no one will notice as much as leaving them on the plant. More light will help as well.

@tapla I just wanted to say thanks again for the help! We gave our Pothos some plant food and its bounced back beautifully - no more yellowing!