Split leaf philos need bright indirect light for leaves to split. Prune dead leaves off close to vine and prune end of vines just above a leaf node to control height/length if you want ☺.

Let's not forget holes. Mature plant leaves also have holes in addition to slits.

Monstera delicosa is one of the first plants that I ever grew when I was 14 circa 1960. I had no problem getting it to produce slits. I vaguely recall growing it under a 100 watt incandescent bulb. I definitely remember counting the slits and holes in each new leaf to measure my progress.

I'm a little late to the party, but I have a young one and I've been reading up. To further clarify what the above posters said, most resources say you won't get split leaves until the 2nd or often 3rd cycle of leaves (dying in the winter, and growing new ones) - so how old is your plant? It could be a couple of years until you get a good amount of split leaves. I hope mine come in the 2nd year rather than the 3rd, I'm impatient for the beautiful holey leaves!

Ive got one potted, its about 8 years old. IME the leaves depend on how fat the vine is that they're growing off. For example my plant came with big fat stems and all of the leaves were split. As I trimmed and repotted those those sections, they kept putting out huge split leaves but the mother plant started putting out many smaller diameter Vines, lots of them, but they stay skinny and none of those leaves have split. Those small vines are now four to five feet tall, 3-4 years old but they've never gotten big and fat and they're still putting out smooth whole leaves. What gives?

Btw I live in New York. It lives on an east facing balcony during the summer we are gets filtered sunlight for about 5 hours a day, in the winter i bring it just inside the frech door, where it gets wicker light but more direct since the oak tree that shades it loses its leaves. Cuttings live in various windows (in various homes, since ive given many away) and everyone is experiencing the same phenomenon..

people underestimate the light conditions indoors. Unless you live very far south where the light is very strong similar to FL.

outside in south FL they grow in partial sunlight under the trees - early or late sun, but shaded from overhead strong hot light.

indoors it definitely needs some dappled moving sunlight - east or west window with at least sev hours of sun. venetian blinds are very good to give that. Direct, really :).

but don't just do if your plant has been in darkness all it's life. increase the light levels over a period of sev weeks.

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