We have a large fireplace made of rocks from the Craters of the Moon park in Southern Idaho. The rocks are very rough and already have some dry moss on them, but really, the whole thing's a kind of eye sore, to me; I prefer river rock. So I started thinking maybe I could get moss and other small plants to grow on the moon rocks. Then it would be quite beautiful!

Our climate is dry and there is no direct light on the rocks. Would I need lighting and some way of misting the moss daily? Any ideas on how best to do this?

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    is this fireplace indoors or outdoors? When you use the fireplace how hot do the rocks get? – kevinskio Feb 13 '12 at 15:07
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    @kevinsky i wondered the same thing but then I saw Adrienne has tagged it [indoors] – Tea Drinker Feb 13 '12 at 18:12
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    Interesting. The house we bought has a fireplace of rough rock with moss already on it. I assume the moss is dead, although I've watered it occasionally anyway. It would be cool if it were alive and growing, so I'm interested in the answers you get. – thursdaysgeek Feb 13 '12 at 22:19

If your fireplace is used regularly you may find it difficult to get moss started - it grows best in outdoor alpine conditions (ie cool/cold, shaded, damp)

That said, you could bring some established moss inside to try on one of the rocks furthest from the fire, and possibly run a fine sprinkler system to keep the stones damp.

I have seen a setup for something similar where a low pressure water feed dripped onto the rock continuously, but at very low volume, providing just enough moisture for a fern/moss bed.


Some mosses from outside will establish indoors in good indirect light. However they need constant access to moisture. For the integrity of your house I could not recommend having fire and water close to each other.

I believe the most practical method would be to set up a planter box. If the dimensions were one or two feet long by 6 inches wide and at least 6 inches deep you could plant ficus pumila or plants like it. This way you keep what you need to keep moist, the soil, away from what should be kept dry, the fireplace. A planter should have a drainage layer, something like one inch of styrofoam peanuts with some landscape fabric between it and the soil. And experience shows you should put a small diameter plastic container in the soil so you can see how much water is in the bottom.

Depending on the exposure you may need to supply additional light in the form of fluorescent or LEDS. I don't recommend halogen or xenon lights because they run hot and will make it harder on the plants


I grow moss indoors in several conditions. If you want moss and other plants to grow on you rocks you could try this. Mix one quart of worm compost, 8 oz. of compost, and three gallons of water in a bucket. soak the rocks in this mixture for ten minutes. Sprinkle heavily with soil. Go outside and gather moss from rocks in your area. This ensures that the moss you are using is adapted to the humidity in your area. You do not need enough to cover the rocks, but 1-2' diameter pieces 3" apart on the rocks. If they don stay, mist them and wrap onto the rocks in a net of organic material. Keep the rocks moist at all times with rain water. I use a used and cleaned cleaner bottle. After two weeks, remove the net. As for lighting, moss does best in bright fluorescent lighting. Some people make the mistake of putting them in dim light indoors. Outside in the shade is actually quite a bit brighter than a normally lit room. I have had the most success using 100 watt replacement fluorescent bulbs with a mirror in the back, to bounce excess light back at the moss. After the moss is well established and has a good amount of dead matter between it and the moss, you can add miniature ferns sparingly. It often takes half a year to get the moss looking completely natural.


I've been reading up a lot on garden railways recently. One tip in one of those was to "seed" the rock by painting milk on it first. This will encourage the moss to grow. You need some moss to start it of course, and the conditions have to be right (see the posts above).

Never tried it, and this is not something I'm not going to do here in Texas; but it seems like it would be worth a try.

Unrelated, and I don't know the exact situation here, but taking rocks from National Parks & Monuments, State Parks, and even City/County Parks is generally prohibited. A reminder to everyone: don't do it unless you have permission from the relevant organization.

  • I thought of the milk method, but it does start to smell after a while. His rocks are indoors. – J. Musser Feb 16 '12 at 2:34

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