Darryl

Thanks for submitting your photos and care details!

Assessment
If you’ve only owned the plant for a week, the black edge damage on the new leaf wasn’t from anything you did – the conditions that caused this damage occurred months ago.  During the time a new leaf is developing prior to unfurling, if the soil was waterlogged or the plant was somehow environmentally stressed, it can damage the new leaf before it even emerges from the sheath.  Here’s my plant and the damaged leaf that occurred a few months after propagating:

Notice that even if the edge of the new leaf (and in my case, the entire leaf blade) – leaf B – is damaged, it can still produce another new leaf – leaf C.  Over the summer, growing outside with nicely filtered light, the plant continued sending up new leaves that weren’t blemished.

And after removing the damaged parts, you wouldn’t even know the plant went through a tough time – here’s my plant a few months later in November:

Monstera deliciosa Pot Sizing Guide: go up to a pot that is roughly the same size as the largest leaf.  Your plant can definitely go up to a larger pot especially because you have two vines.  My plant (below) has only a single vine.

I potted up the plant with 2 parts standard potting soil and 1 part bark chips, gave it a thorough watering (as you should with all newly potted plants) and the Monstera roots recovered after two days:

Environment
While I can’t definitively see your light situation, I’ll recommend that you put your Monstera RIGHT IN FRONT of your largest window – it’s the bare minimum if you want your plant to grow well in the long run.  More specifically, in indoor natural light context, the minimum indirect light range should be 200-400 FC and 2-3 hours of direct sun is tolerable.  If you want a grow light, it should measure around 400 FC at the leaf and be kept on for at least 12 hours a day.

More on measuring light: indoor natural light context and grow light context.

Effort
WHEN to water: whenever the soil is about halfway dry.  HOW to water: thorough and evenly soak all parts of the soil and let excess water drain away.  Use a 3-1-2 fertilizer on a regular basis.  More on fertilizers HERE.

Expectations
There’s nothing you can do to reverse the damage on that leaf but with good light and care practices, the next leaves should be blemish-free.  If you repot it into a larger pot (as large as its largest leaf) with drainage holes so you can easily soak all parts of the soil, the plant will continue to grow well – as long as you provide it with adequate light.  The oldest leaves (the lower ones) will eventually yellow and die off – which is completely normal but with good light, your plant would have pushed out several new leaves.  Good luck!

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