Remember, YOU are the BOSS, NOT the plant. Yours needs to know who is in charge., but it is very healthy.

And when you prune don't just cut off leaf blades or through leaf petioles. That will leave you with a petiole which will die off. Cut actual stems.

1. Is it possible to encourage upward growth, or is that just not-monstera? Yes, you can, though it might take a 2-step pruning process.

Step 1: Cut through a stem a few inches above the soil line. This will force back-budding.

Step 2: Once new buds emerge, select a bud pointing upward (on the top of a branch or on the stem on the side facing an imaginary vertical line vertical to the drain hole and prune back to that bud. This will produce upward growth until the plant again wants to lay over. When that occurs, repeat the process. The trick is not to allow the plant to allow the plant to grow unencumbered by pruning for too long. This forces you to remove plant mass the plant has already invested a considerable amount of energy to produce.

2. Can I prune it/trim it back without killing it, and if so how? I hate to lop off stems/leaves, but this thing is spreading like crazy.

Best time to prune is when the plant is about to enter the most robust part of the growth cycle - just before the summer solstice when light levels are brightest and days longest. This makes for a fuller plant because it ensures shorter internodes and smaller leaves on new growth that occurs Pruning through stems/branches ensures back-budding; whereas partial defoliation (removing one or some leaves) doesn't.

3. I should just leave those aerial roots to do their thing, right? There is no advantage in allowing them to remain attached to the plant unless they are directed so they root in the soil where they will have access to water and nutrients, which means you have a choice. IF directed to root in the soil, depending on where they are located on the stem, they might add stability to to the plant itself, but will be a bit more of a headache when it comes time to do a full repot. Your plant will grow with considerably more vitality if you include an annual or biannual repot with root-pruning and a change of soil to your care regimen.

Al

Didn't people use to put in those special stakes - I think they were moss-covered?

With this one, may I ask, what happened to what was at the end of those 2 brown ends?

I used to have one of these and I had no stake. I had finally found a good spot for it, and it was happy there, and then unfortunately, I killed it with fish fert because I didn't know about flushing the soil back then. So, folks, don't be like me!

It's gorgeous as is, too. What about putting it up on a plant stand or a stool or a low table?

And, cute kitty!

Didn't people use to put in those special stakes - I think they were moss-covered? Yes. What you're asking about are a type of moss pole, unless I'm misunderstanding the question.

Al

Yes, that's right - moss-covered poles. I remember those. I haven't seen one in a store in ages, I guess one would need to rig one up.

For myself, I like the sort of all-over look for this plant. However, maybe a pole would give the OP the look they want. (There are lots of pics online.)

So, would the roots climb the pole, if there were a pole? Or do people who use poles just sort of tie the plant to it, as it spreads?

Sorry to post-and-ghost -- this has been a bananas week. Thank you all for your advice! Saturday is monstera day; I'm going. to trim those aerials, and maybe do a little pruning of one or two of the smaller branches on the left. I will wait a few months to attempt the back-budding.

Currently, I have it sort-of propped up with two bendable moss poles from Amazon -- but they're not really moss; they're coir, since I'd read that moss is not really sustainable. The aerials are supremely uninterested in the coir, and tbh, it's pretty scratchy so I don't blame them. I'm trying to train the main stalks/stems of both plants to go upward, ostensibly using the stakes, but have been totally unsucessful so far -- they just want to go sideways.

And Earl (Grey) thanks you for the compliment. ;) He is a lovely cat and he does *not* try and eat the monstera.

The Philodendron clan and related genera are either climbers or self-heading. Monstera is a climber that wants to grow into the tree canopy. I once had a common heart leaf Philodendeon (used to be called Philodenron oxycardium. Had it against a wall, only northern light at 41 N.), it begin to climb the wall with its root attaching themselves to my WALL, which indicarted a problem with wall moisture, btw. Given a mild, humid evironment, they are extremely luxuriant! Put it outside in the growing season if you wanna see real expansive growth!