What is this a sign of? Too much/little water? Too much/little light? I mist them occasionally and the soil seems moist. Should I try to add enough water so that it drains out from the bottom some? They looked better in the store.

@Roose

I think it is a matter of too infrequent watering, but would need to know the specifics on your growing conditions. This time of year, with the sun so low in the southern sky and our extremely short daylight hours, I would doubt it could get too much light.

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These ferns like humidity, too. So indoors in winter when the heat is drying the air, plants suffer. They grow in the shade here, so are good plants for low light.

When you water, take the plant to your shower and make sure you give it a good, generous 'rain'. Get all the leaves wet and water until lots of water comes out the bottom.

It will also help the plant (and you!) to spray the leaves between waterings with plain water just to keep the humidity up. You can add a tiny bit of fertilizer to the spray water, but in winter they don't need hardly any fert. I would not fertilize it with anything else until the weather warms up in spring. (warm enough for you to open the windows, at least) Fertilizer can burn the leaf tips like that.

My ferns are in my green house. During this time, I water moderately every couple of weeks. If I have time, I spray them over the top, every week. During the summer, I flood them once a week and twice if time permits.

Your greenhouse should be great for humidity. Every couple of weeks seems like not enough for a fern that likes to stay moist, though. I'd go for lighter waterings more often, for that guy, I think.

Try hefting the pot to see if it's gotten light, after a few days. With all this super warm weather, that plant still thinks it's summer, maybe. It also may have dried out to the point that the potting medium doesn't get entirely wet when you do water it. Have you soaked it in a bucket recently? Again, lifting the pot will tell you if the medium has dried out to a 'brick'.

Giving it a good, long soak in a sink or bucket of water, so that the root-ball can really get saturated is what I would do. Otherwise, the water you dump on it is simply running straight through, without truly wetting anything.

Thanks everyone. Not doing to good here. I've been making sure the soil is moist and able to drain. Don't know if I'm watering too much or if not enough sun or too much sun. The fronds have gotten all dark green and boiled-spinach looking. The humidity is between 45-60 and the temp stays between 65-75F

In a couple spots it seems the healthy green wants to come back but I feel like I'm flying blind since. Wish there was a more scientific resource. So far though I've learned about different soil/water retention levels and the soil I have since it's store bought from lowes is probably 10% water retention. It feels moist to the touch on the top but I can't be sure. These ballpark and feel measurements never suit me.

I'm glad I started with these cheapo little plants and not a $50 monster since I clearly don't know what I'm doing.

Added a second closer image. Little guy is trying to live.

@Roose, keep in mind that just because you are doing things right, the damage was already done. Heck, that damage probably started in the store where you purchased the plant. Generally speaking, our big-box store and grocery store employees don't have a clue how to care for these tropical plants. Our Lowe's is "famous" for under-watering or over-watering their tropical plants. The thin, tender fronds that were damaged, probably from dehydration but possible from another cause, don't simply recover to their normal, healthy state. New growth is where you want to see healthy fronds. Your plant may well lose many if not most of those older fronds. Don't fret about that. It won't be pretty but that's just Mother Nature's way of saving the plant by sacrificing the weak, damaged fronds.

I did not notice whether you are misting/spraying those fronds every day or two, but that will help raise the humidity as well as allow the new fronds to stay hydrated.

Keep working at this. I have confidence you'll get these plants through this rough time.

Another thought, darker green leaves can mean a couple of things - first is that the plant can compensate for too little light by making more chlorophyll, and second would be a response to a high-Nitrogen fertilizer. Neither is really any cause for concern.

I'd recommend gradually moving them towards more light if you can, or give them some extra light by hanging them near some fluorescent lights.

Do make sure that the pots are significantly heavier after you have watered, too. If not, the water is just flowing straight through, it's an indication that the potting medium has dried up and become a solid brick inside the pot. Not absorbing any water.

Thanks for the support. I'll keep trying. Just discovered the light sensor on my smartphone can be used for a light meter app. Now I'm getting somewhere, just need to find some healthy ferns and get a reference for lux.

Any idea how many lux medium indirect light is considered?

At my NW facing window about a foot away I'm getting around 1,000 lux right now at 4pm est.
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The app is called light-o-meter for android if you're curious.

Neat, I'll try it! . . . I got same as you, around 1000 in the shade outside in my driveway, 1400 in dappled shade and over 3000 in sun. I'll try it again tomorrow around noonish and see what the shade reading is. Probably a lot higher in the summer, though. All plants have a range of light in which they like to grow, of course. I'd say late afternoon shade on a winter day is about the minimum they'll want.

Boston Ferns grow in full shade here. If they get too much sun, they turn very pale green and gradually die off. They are an invasive weed here so I really don't try very hard to cultivate them.