My understanding is that schach must be from a plant that specifically grows from the ground. If this is not so, would there be any problems using:

  • algae / seaweed / water lilies / swamp scum - these grow or float in water
  • fungi or moss - such as mushrooms or other similar items that are not plants but grow on the ground or the bark of trees
  • hydroponics - plants grown in the air in a greenhouse
  • judaism.stackexchange.com/questions/13899/…
    – Double AA
    Commented Oct 2, 2014 at 3:07
  • +1 for the hydroponics, which can also concern the arba minim. @DoubleAA, are you saying that this question isn't lemaaseh, or that he deals with it in that Teshuva along with the Lechem Min HaShamayim?
    – Yishai
    Commented Oct 2, 2014 at 3:39
  • @Yishai Hydroponics is actually the main subject of the Teshuva. He uses the Mahn as a possible analogue.
    – Double AA
    Commented Oct 2, 2014 at 3:44
  • I honestly don't understand the background/basis of the question. If you think it's so, then it's not a question. What makes you think it isn't so? And if it isn't so, what makes you suspect, as you seem to, that there may yet be something wrong with these specific forms of vegetation?
    – Seth J
    Commented Oct 13, 2014 at 20:05

3 Answers 3


See: אהלי שם : אוצר פסקי המועדים who writes that one who uses water grown plants has what to rely on, though ideally one should avoid using them.

This comes at the end of a discussion (and list of sources) on plants grown in a pot. Seemingly, the same would apply to your other categories.

  • +1 for a great source! ....why would you say the same about mushrooms? I don't make a ha'adamah on mushrooms....
    – MTL
    Commented Nov 11, 2014 at 23:14
  • It's no worse than 'Gidulei Mayim' and there's no requirement for it to be 'ha'adamah'
    – Zvi
    Commented Nov 11, 2014 at 23:23

My understanding of the issues at hand tells me that your first and second groups are not valid for scach, while your third group might be subject to a machlokes.

  • Algae and the like are not גדולי קרקע, as they do not grow in the ground.
  • Mushrooms (a form of fungus), even when they grow on the ground, are not considered to be גדולי קרקע with regard to brachos, because we make the bracha of shehakol rather than ha'adamah, because they do not derive nourishment from the ground.
  • Hydroponics might depend if you make the bracha of ha'adamah on them or not -- if you do, then they are גדולי קרקע; if you make a shehakol, then they might1 not be גדולי קרקע.

This is my own, unsourced understanding of the issues at hand. If you disagree, please feel free to leave constructive comments to let me know where I went wrong.

1 The reason that I wrote "might not be," is because a case might be made that these plants are, by their very essence, גדולי קרקע and not subject to change based on where this particular specimen grew. I can't say for certain whether or not that is true, but my (unbased) feeling is that it would depend on where this particular specimen grew.
In retrospect, this may have been the intent of the question :P


Rav Abadi OY 1: 224 was asked whats the din of Shach which comes from an atzitz sheino nakov (plant in a pot without any holes) is it considered detached or attached to the ground? He answers that he isn't so sure ,but simply it makes sense it is considerd detached in all aspects . However, still one shouldnt use it from a rabbinic standpoint because the Rabbaniom made a decree to give maaser of fruits from a non-preforated pot. He ends off by saying he hasnt seen anyone discuss this issue.

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