Tap water often has a lot of dissolved salts and minerals in it, and these can cause moss to turn brown and eventually die. A much greater problem with indoor mosses where these salts and things have nowhere to go, but if drainage is poor or for some other reason the salts and minerals are building up it could also be causing you problems outdoors. Usually if this is the problem you can see gunk on the edges or tips of the browned leaves... hard water in Indiana does that to mosses, anyways.

Patrick Alexander

Another explanation is over-watering in warm weather will led to fungus infections similar to the brown spot fungus that affects lawn grass. Here in the South, it's actually easier to have a drought in hot weather. The moss goes dormant and I don't have to worry about fungi killing it. Cool weather...love the rain and it's safe to water again (but only with distilled water). Patrick is right about tap water and it's perils for moss.
Good Luck and watch the water.
I've killed more moss with water than any other way.....jjane

I am heart broken about the info you posted about moss truning brown from too much minerals.....as that is what has happened to me......I thought it was just the summer time heat as the moss will dry up and almost look dead until the cool damp weather returns, and I couldn't figure out why it was taking so long for my moss to green back up like it was in the spring time... I never thought of it being the minerals building up, and eventually killing the moss.

I invested so much time and effort into all of my miniature moss landscpaes, and 75% of all my moss has turned a gold brown, and with the cold damp fall weather now upon us here in the north east U.S., my moss have all failed to return to their brilliant lush green color like they do after a hot dry summer.

After reading so much, and going online to find as much info as possible, your mentioning of the moss being sensitive to minerals is the 1st time I've heard of the problem, but it all makes sense now. I stopped using distilled water over the summer, and started watering with the 0.69 gallon spring water because it was 0.31¢ cheaper than $1.00 per gallon of distilled water. I'm now paying for it with dead "mineral overdosed" golden brown moss on these beautiful miniature rock landscaped I created last year. There is no way I could use my tap water from the faucet because of the chlorine that the town has loaded it with. Chlorine and moss won't work well together.

It's time for me to start over.... it shoudn't take too much effort replacing all of my miniature moss I have growing around my lava rock landscapes afixed to my flat slabs of slate. I use a special combination of muck soil to keep the moss attatched to the rocks...

I have a wild source of moss growing on my family's land, on a GIANT 100+ year old stone wall, and I never take more than I need, and leave PLENTY of moss behind so the moss can re-juvenate for the next year. The last thing I want too do is a clear-cut of moss. The type moss I use that grows on this old OLD 10 foot tall stone wall grows in tiny clumps, real compact miniature growth, and the wall I gather it from in the wild gets about 20% indirect sunlight each day.

If I can, I'll post some pictures of the before and after - that is pictures of the dead moss that overdosed on water minerals, compared to the moss I am going to replace it with, that is once it gets established.

I find my moss grows BEST in the winter time, as it may go below zero degrees F (not C) at night in the winter, but in the day where I keep my moss on my balcony, the temp rises to about 35 degrees to 45 from the radiational heat off of the brick building I live in. I also cover all of my moss with ANY snow that is around, as it greens up my moss like no other. Snow has always been the best method of keeping my moss green and alive all winter.

Well, no more spring water for my future moss. I should have known about the mineral over-dosing. For now on, I am only going to use distilled water, rain water, and snow.

Great Idea! I was thinking of using dechlorination tabs in water set out over night, but this is a much better idea. I have just planted our moss and it too has golden brown areas. I'm also afraid that some of it gets full sun in the afternoon for about 2 hours. Thought that was the culprit, but minerals in addition to that cannot be good.

Buy a reverse osmosis set up and use that for the mosses.