This is a slight continuation of my other post where I was trying to create realistic hollows with weather due to temperature changes due to bio minerals called Hearthstones. I was wondering if plant life would be possible in the hollows with the hearthstones as they currently are, which are crystalline organisms that can reach the size of a house and go through heating and cooling periods. The cool periods of the hearthstones is when the hearthstones adsorb ambient heat, light and radiation until temperatures in the hollows reach below a desired threshold of about 62 degrees Fahrenheit where they then will enter their heating faze.

Hearthstones become more and more inefficient the larger they grow, so hearthstones grow to a maximum size of ten meters tall and 3 meters across. Most hearthstones are about the size of a foot ball but vary in size. The hollows tunnels that the hearthstones inhabit are caverns and openings carved from underground rivers through limestone, underground lakes, lava-tubes,and ancient organisms. making the planet's crust riddled with caverns. Think the hollows from Gears of War.

The hearthstones will then release light and heat radiation that is predominately in the yellow and red spectrum but sometimes white depending on the species. The Hearthstones during this face with raise the temperature in the hollows to around 82 degrees Fahrenheit before entering a cooling period once again. So most of the time the light in the hollows is around that of a overcast day. With these conditions I was wondering if it would be possible to have plant life in the hollows.

So my question is: Is photosynthetic possible and if not what needs to change about the headstones to make it possible, or should it be mostly fungal and lichen based foliage?

  • $\begingroup$ 1. 62 and 82 degrees are has high as the hottest deserts on Earth. If there's no water the hollows will bone dry death pits, if there is water they will be lethal pressure cookers. 2. Your color coding sounds a bit weird. If you aim for some cheap realism, check out black body radiators this will give you an interesting correlation between temperature and light color. If you were to add the size of the stones and area with the vegetation I could calculate how hot, which color or how many stones you need to let certain plants grow. $\endgroup$ Jan 31, 2020 at 11:03
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    $\begingroup$ @TheDyingOfLight I would guess from the values that OP refers to Fahrenheit not Celsius but clarification would be useful. $\endgroup$
    – quarague
    Jan 31, 2020 at 14:04
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    $\begingroup$ @TheDyingOfLight I added the size of the hearthstones and the approximate size of the caverns, hope that helps! I'll add any more information if needed. Thank you so much for letting me know of these changes I needed to make. $\endgroup$ Feb 1, 2020 at 0:45

1 Answer 1


The best wavelengths of visible light for photosynthesis fall within the blue range (425–450 nm) and red range (600–700 nm). Therefore, the crystals should ideally emit light in the blue and red ranges to allow growth of plants that do photosynthesis.

Your temperature ranges appear to be like a mild to warm spring and are less of a concern than the wavelengths.

You did not elaborate on how or if water was available in the hollows. You would need this in reasonable amounts as well.

Plants also need carbon-dioxide in some concentration. As long as your hearthstones do not reduce that, plants will thrive in your pseudo-hothouse environment.

  • $\begingroup$ The best photosynthetic wavelengths for Earth plants are in the blue and red range. This is not necessarily the case for the OP's plants. $\endgroup$
    – Vikki
    Feb 1, 2020 at 5:49
  • $\begingroup$ The question implies Earth-like plants (i.e. "should it be mostly fungal and lichen based foliage"). The plants in the hollows can have any process they like to convert light energy into chemical energy for storage. It would not be photosynthesis, but like-photosynthesis. $\endgroup$
    – user72081
    Feb 1, 2020 at 12:28
  • $\begingroup$ Sorry I should have added that its moist in the Hollows like a cave since water from the surface dribbles down into it. Likely leading to lakes and rivers inside the Hollows. So during the raining or snow melt there is likely more water in the underground than usual. So the Hollows likely have a higher humidity than the areas above it. $\endgroup$ Feb 2, 2020 at 1:31

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