I don't know what is causing the brown spots but the white spots look like water spots, probably from misting. There are different recommendation for how to clean them. I used a cloth dampened in diluted milk (a tip I read somewhere on here) to clean my leaves and it worked wonderfully.

If your purpose of misting is to increase the humidity for your plant you may want to read this recent thread about misting plants, as it explains that it isn't effective in increasing the humidity for your plant and isn't a necessary practice. Not trying to criticize your plant care because I'm far from an expert. I used to mist my plants before I started learning from the members in these forums.

Hopefully someone else can help you with the brown spots.

Oops here's the thread refereed to

http://forums2.gardenweb.com/discussions/4095123/is-misting-your-houseplants-really-necessary?n=13

Help! I'm having the same problems! https://imgur.com/a/CW8j7#F0kgiYA I'm fairly certain it's not a watering issue. The plant has stayed relatively dry the last few winter months. The air in my apartment is quite dry so I've started misting it daily a few days ago. However, the spots seem like they're still growing and spreading to new leaves. The plant is in front of a very large west facing window. There's a bit of a cold draft as the windows aren't very well insulated. http://imgur.com/wlvaw6f

Additionally, the substrate is usually dry enough that I can pull out the whole plant and observe the rootball. I don't think it's underwatered, because it's always slightly damp. These spots only appeared in the last month. I took a close look at the roots today and didn't observe any rotting. Someone on Reddit suggested it might be a nutrient deficiency. Should I fertilize? I'm located in SE Michigan.

The cause of the necrotic leaf margins is due to impaired root function. The underlying causes of the plant's inability to take up water and distribute it efficiently to the most distal parts (leaf tips/margins) is one of 4 things. Too much water, too little water, a soil solution TDS level too high (TDS = total dissolved solids - a high level of mineral salts from tapwater and fertilizer solutions), or severe soil compaction.

Your plant should be on a nutritional supplementation program that takes into account your soil's properties and your watering habits. Until we know something about these influences, there is no way to give meaningful advice.

The best thing for your plant would be to develop a plan and stick to it. I would start monitoring your plants' water needs carefully and flush the soil thoroughly the next time it needs water, then continue to monitor moisture needs and water only when the plant first appears dry. I'd work toward locating or making a soil that allows you to water correctly (so you're flushing the soil when you water) w/o having to worry what's happening will be the norm. You should find this overview helpful.

Al

Thank you, Al. The soil I'm using is a standard potting mix (Miracle-Gro, I believe) and it is fairly loose in the pot. I know for sure I'm not overwatering - I'm not seeing any other signs of it. Possibly underwatering, but I was nervous to water too frequently because I don't want to overwater. I usually leave my water to sit out for a few days before pouring but I'm not sure what's in there that might not evaporate.

The spots appear out of nowhere - there' s no sign of them before they appear (no yellowing, etc). Perhaps I should try watering some more and see what happens. The roots looked healthy so I'm sure I can get away with it.

I don't veer much from my routine which is why it was so surprising. The only thing that has changed is the temperature near the window and amount of daylight.

Are you sure it's not fungal?

Miracle-Grow is a difficult soil to grow well in.

It's not fungal, and don't invite the fungaluglies by misting. You can eliminate over-watering as a potentiality if you use a 'tell' to let you know when to water. Buy a 5/16 wooden dowel rod from the hardware store. Cut it in 2 - 24" pieces
and sharpen all 4 ends in a pencil sharpener. Push it into the soil -
all the way to the bottom. Don't water until the day it comes out dry, and when you do water, make sure you are wetting the soil fully (no dry spots!) and at least 15-20% of the total volume of water applied exits the pot. Let me know if you think the soil would remain soggy so long it would wreak havoc on root health or function if you take that course, and I'll help you deal with it.

Al

I have the same issue with mine that I've had for several years. Its in gritty mix now and all of the brown spots are on older leaves so it seems like the gritty mix solved the problem. Although I do wonder if I'm fertilizing enough. How much fertilizer/water solution do you run through the pot Al? And do you try to saturate all the gritty mix first, then water with the fertilizer solution? Seems like a stupid question, I know, but I started thinking about how to maximize the nutrients available to the plant since the gritty mix doesn't retain much water and just wonder if they're getting enough food.

Its not the amount of watering your doing, its just the plant gets no fresh air like outside. Gradually Increase light and putting a fan on it would probably solve this.

Mat, I can't imagine that adding a draft would solve anything. Everything I've read says to move the plant away from drafts. Also, it gets more light in my floor to ceiling west-facing windows than most houseplants. I don't think lighting is a problem either.

Josh - The plants I have under lights for the winter get fertilized each time I water with 1/4 tsp of FP 9-3-6/gallon of water. When I water, about 10-20% of the total amount of water I apply exits the pot. If your plants are getting natural light and you think they could do with more, you might try fertilizing at the strength I mentioned, then water twice so you're flushing the soil, then repeat.At these low doses, there isn't much concern about over-fertilizing unless the soil is VERY dry. I'm watering well before there are any indications of drought stress, and have seen 0 indication of plasmolysis in any of the plants.

Keep in mind that plants make their own food - glucose. Fertilizers are the building blocks they use to grow and keep their systems orderly.

Charles - There is a difference between air movement and a cold draft or a hot wind. Air movement upsets the boundary layer (of air) surrounding the leaf and increases transpiration. This means that more nutrient solution is moved through the nutrient stream - generally a good thing. Air movement can also have a significant impact on keeping pests and diseases in check, and it helps promote back-budding. On the other hand, if your plant's ability to move water to distal parts is limited by poor root function/health, air movement can be a negative insofar as the plant's appearance goes, because increasing water demands combined + an inability to efficiently move water to the plant's distal parts will produce more necrotic leaf margins or tips.

I have 2 - 20" box fans (set to low speed) in my grow area + a 12" round fan blowing over a plastic cake pan cover ($1.50) that holds 2 gallons of water with humidifier wicks in it to increase humidity, which really decreases the humidifier's run time.

Too, MG soil has water retention issues you need always consider because of how water retention impacts root health/function. How much/often you water is always a consideration when you're using a water-retentive medium.

Al

Al, it seems like I have to let much more than 10-20% of the water exit the pot in order to thoroughly saturate the gritty mix. Occasionally, I've found dry spots a few inches beneath the surface when it appeared to be completely soaked. Maybe I didn't screen my turface and grit good enough? When you say fertilize at the strength you suggested then water twice then repeat, do you mean fertilize at one watering then water without fertilizer for the next two waterings, then fertilize again? It seemed like you suggested to fertilize at each watering so I'm just confused what you mean by "water twice."

Someone needs to invent a pot to be used with gritty mix that has an outlet valve with a false bottom that will somehow defy Bernoulli's principle and drain upward through a hose into a sink drain.

Imagine if Newton discovered apples falling upward .................. ;-)

A fella could rig up a hole in the bottom or the side at the bottom of a pot that would accept a tube so it's air tight. The tube would be usable in all of your pots and connected to a T-Y configured like a sanitary T-Y:

http://shop.advanceautoparts.com/wcsstore/CVWEB/staticproductimage//N4016C/large/5019702_dag_47353_pri_larg.jpg

Another section of tube would connect to a water source with 30-40 PSI pressure flowing through the fitting, which should suck any perched water from your pots like a champ. Yes?

Al

I think I understand where you're going with this, but not quite. Could you elaborate please. If this works and I don't have to lift what is probably nearly a 100 lb pot and set it on top of a bucket to water, I would never be able to repay you lol.

Al

Ahhh yes now I see what you're saying. That's a great idea, as usual you're always very helpful and it is greatly appreciated. I'll have to experiment with that when I get some time.

For the maximum amount of suction, make sure the fitting isn't a 'Y', that it's configured so the line of flow is in a straight line as it passes the secondary in-flow line.

Al