Can houseplants reduce humidity?

Plants will not reduce humidity, more like the opposite.

Nope. Buy a dehumidifier for your bathroom, and set the thermostat a degree or two colder than usual. Look for air leaking into conditioned spaces from poorly sealed doors and windows.

Plants are great, but they won’t do squat to help in our ultra humid climate.

It's not silly, it's beyond silly.

House plants need watering and what water that isn't used by the plant simply evaporates, adding more water to the air.

Besides, even if it did, just how much time and effort would you be willing to put in on an almost daily basis toward upkeep of the plants in watering, fertilizing, making sure they got enough sunlight to survive by rotating them to light sources, etc.

Like mentioned, just get a dehumidifier or two and plug those suckers in, problem solved.

Numerous plants can help stabilize humidity in a room or building.

I believe Ferrari has a large clean warehouse they manufacture their engines in and they have a bunch of trees in planters in the ground in it. The tv show I saw said they did it Bc it helps to keep humidity constant which enables them to manufacture the engines more accurately.

Thanks for the advice guys, but like I said I'm not trying to solve an elevated humidity level with plants. I'd just like to add some plants, and in doing so I don't want to increase humidity, and maybe even lower it a tad or at least regulate the levels if I can. I don't know if it's possible to shave 1% RH off the top end, but if it is then it's ok if the plants add 2% to the bottom end of the range. In other words, even though they might elevate the average RH, it's still better if the max is lower.

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House plants need watering and what water that isn't used by the plant simply evaporates, adding more water to the air.

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Understood, but the point is these particular plants don't need much watering due to their ability to absorb some from the air when it is available. A bit of googling tells me that a central AC can dump as much as 20 gallons of water per day from the air. If I split a gallon per week across a handful of plants, that's just 1 gallon that I'm adding to 100+ gallons that are circulating through the house anyway... not a huge deal. And if they smooth out the highs and lows, it could be a net benefit.

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Besides, even if it did, just how much time and effort would you be willing to put in on an almost daily basis toward upkeep of the plants in watering, fertilizing, making sure they got enough sunlight to survive by rotating them to light sources, etc.

Like mentioned, just get a dehumidifier or two and plug those suckers in, problem solved.

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I am all about low-maintenance and little time investment, and these particular plants are good for that. I believe spider plants, for example, live just fine in peoples' garages without light or water for months at a time. I can't see spending more than 10 minutes per week tending to plants. If they take more time than that, I'll just get rid of them.

But again this is not intended to be a replacement for a dehumidifier.

Your AC unit is to big for your house

I didn't mean for this to turn into a thread about diagnosing high humidity, but here goes.

I have 2 AC units totaling 7 tons cooling ~3400sqft. The daytime/living areas of the house are about 1900sqft with a relatively new 4 ton unit cooling it, and it stays pretty comfortable.

The sleeping areas of the house are about 1500sqft with a very old 3 ton unit, and humidity stays pretty high back there. One big reason is I have ecobee thermostats on both units, and we have them set to minimize energy use. Some of you guys will lose your shite to hear that the temp stays about 73-75 degrees back there during the day, so it doesn't run hardly at all from 8am to noon, and then noon to 4PM it runs for about 30 minutes at a time with 15 minute breaks. Here soon around 6 it will start running for 1.5 to 2 hours at a time as it brings the temp down a bit. All told that unit runs about 14-16 hours on these hot and humid days at these relatively high setpoints, and I'm not sure how typical that is. RH tends to run around 70% at times (according to the ecobee, not sure how accurate it is).

So I'm pretty sure I could drop the humidity substantially by dropping my setpoints by a couple degrees and giving it a couple more hours of run time per day. Even though that unit is very old, my AC guy says it still runs like almost new, and my ducts are in good shape. My attic insulation could stand to be upgraded.

I might do a full efficiency workup as suggested above, but before that I will address some of the obvious issues in the living space. For example, in this 1500sqft space (there is a hallway door that is usually closed dividing the house into sections) there are 3 bathrooms, an uninsulated attic access, and a 40 gallon gas water heater in its own closet that is vented to the attic. Every day this area sees 2 showers, 1 or 2 baths, and of course the constant (though seemingly minimal) infiltration of attic air as well as the standard evaporation from regular bathroom use.

So I have a lot of points to attack, like adding an insulated hatch to the attic access, upgrading the bathroom vents (maybe to ones with humidity sensors so they exhaust all the steam after a shower), and maybe modifying the water heater closet where it exhausts into the attic. I'd like to address theses sources of moisture before brute-forcing the humidity issue via AC mods or adding a dehumidifier.


So yeah, my question about plants was just one piece of a multi-pronged plan of improvements.

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So I have a lot of points to attack, like adding an insulated hatch to the attic access, upgrading the bathroom vents (maybe to ones with humidity sensors so they exhaust all the steam after a shower),

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I looked into those—they’re pretty worthless in humid climates. Yes, you can set them to run for a particular period of time, or unti a certain ambient humidity is reached. But they’re removing air from the conditioned (ie, dehumidified) air space of your house, and new air is coming in from elsewhere—cracks, crevices, openings. You are essentially pulling out air from the humid shower while even more humid air is being drawn in from outdoors. Most places in the world, that lil sucker vent will do the trick. Not so here in the swamp. For the majority of the year, the new air replacing the steamy bathroom air is going to be just as humid or more humid than what you’re venting to the outside.

A room sized dehumidifier costs pennies to run and can be set to run for 2-4 hrs after showering. It raises the ambient temp in the immediate area by a few degrees, but it will absolutely make the area drier.

I’m going to install a whole house dehumidifier at some point soon.

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I’ve had humidity issues for a while but can’t seem to find anyone in the nola area that can accurately diagnose/make a recommendation. Two have claimed my tonnage is right for the home. I have some mildew starting to crop around ac grates. Anyone have any suggestions in the nola area?

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Paul LaGrange is a forensic building consultant in New Orleans who can likely identify the cause of your problem(s). He hosts the Home Improvement Show on WWL 870 radio and fields calls helping to ID moisture issues from homeowners on a weekly basis. He states problems as you describe is usually not one issue, but often a combination of several issues working in concert. He also states most of his work week is crawling though attics or crawl spaces locating the cause of residential moisture issues.

You can call or text into to his show Sat AM (11 am -1 pm) to describe your issue and see if he can help ID the likely issue(s) - I’ve learned a great deal listening to his show the past few years.

Here is his website. LINK

Get a dehum. Keep your RH levels around 45%. It’ll feel like a different house