Growing stuff underground can be a challenge - even if one finds ready sources of water. The key problem seems to be lack of readily accessible sunshine in The Underdark.

Question: what spells work for growing plants underground?

Mimicking this sunlight itself is problematic. Even spells with actual, literal names such as Daylight give neither daylight nor sunshine.

Fortunately, one does not need 'real' sunlight to grow stuff. But which illusions can offer a reasonable facsimile? The author guesses that some illusions must be better than others. Major Image lasts for quite some time should one cast this at 6th lvl+. Programmed Illusion also lasts quite a while, though it would keep turning the lights on and off. Mirage Arcane would provide light for everything inside of a square mile, but needs replacing every ten days. Perhaps make it grow via eternal torchlight? No idea.

To throw a spanner into the gears, we don't even know if illusions are real or imaginary. Possibly this fake light would not even sustain a tanning bed.

Sum up: Can powerful illusions provide enough light spectrum so as to grow real-living plants?

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    \$\begingroup\$ Tim, the dungeons-and-dragons tag is to be used for questions asking about D&D across all or multiple editions or D&D as a whole. You do not need to add it to every question. Please only tag with the appropriate specific system/edition (eg. dnd-5e). \$\endgroup\$ Commented Apr 2, 2020 at 3:15
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    \$\begingroup\$ Related: Can I use Silent Image to create the illusion of a torch that illuminates the area? \$\endgroup\$
    – BBeast
    Commented Apr 2, 2020 at 4:48
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    \$\begingroup\$ Also, @TimofTime, what exactly is your question? First you ask 'what spells work for growing plants underground?', then you ask 'Can illusions provide enough light to grow plants?'. These are different questions: the former allows for any spells, while the latter asks exclusively about illusion spells. \$\endgroup\$
    – BBeast
    Commented Apr 2, 2020 at 4:58
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    \$\begingroup\$ @BBeast Seems clear enough for me. Asker assumes light is needed, and explains his own ideas. The wording clearly implies they want normal plants growing for extended amount of time, like they do on surface. Should some other means of making normal plants grow underground exist, that seems fine solution for the explicit question. Doesn't seem unclear at all. Of course the problem is, RAW doesn't specify much about biology in general or plants in particular, so I don't think there is a strictly rules-based answer. \$\endgroup\$ Commented Apr 2, 2020 at 6:11
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    \$\begingroup\$ @Mark At the very least daylight does not produce sunlight \$\endgroup\$ Commented Apr 2, 2020 at 7:21

1 Answer 1


Work it out with your GM

Trying to emulate real-world physics, chemistry and biology by strictly following the rules of the game, which are not designed for this task, is a futile endeavour. They don't work properly, because they are only designed to give a satisfying combat and roleplaying experience, not an accurate botanical simulation.

Therefore, you're going to have to show some flexibility and adapt the rules to your use case (Garden Simulator 3000, a RPG). Your GM (or yourself if you're the GM) is the authority on what works and what doesn't:

  • Need Daylight to produce usable light ? GM can decide it does.
  • Can't know if illusions are real ? GM knows.
  • Need a new spell that produces dim light in a 30-foot radius for 30 days ? GM homebrews the "Sustained illumination" spell.

Think outside the box and work it out.


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