Opening Window Shade on Shabbat in Front of Plants

The Aish Rabbi Replies

It’s actually an excellent question. The concern with doing so relates to the forbidden activity of planting, one of the 39 types of labor forbidden on Shabbat. As the other forbidden categories, “planting” is really a header for an entire class of activities. Thus, it is not limited to literally placing a seed in the ground, but more generally refers to doing any activity which benefits plant life – such as watering, fertilizing, pruning, weeding, etc. Thus, if you would open a window specifically in order to cause your plants to grow better, it would be prohibited.

In the case you describe, however, there is more room for leniency. If your reason for opening the shade is entirely to bring light into the room and the light which reaches the plants is entirely inconsequential to you, then your action is primarily judged to be a permissible one and not one of “planting”. Now ordinarily, it is not sufficient to have another intent in mind if you know without question the forbidden action will occur as well (based on the halachic principle known as “psik raisha”). Even so, many are lenient in this case because the “labor” accomplished is so imperceptible and indirect that it is not counted at all if it’s incidental. Only if you had actual intent to make your plants grow would the negligible amount of growth induced be considered a forbidden act. Others, however, are lenient only if in addition to the above reasoning, the labor is done indirectly as well – such as if the plants are not near the window and will not receive any direct sunlight when the shade is opened. (Even if the sun will shine on them later in the day, so long as they will not immediately receive sunshine, the act is considered indirect and is allowed.) It should again be noted, however, that if you do care about your plant’s improved growth, even if your main intention is to illuminate the room, then opening the shades would indeed be forbidden.

(Sources: The Shabbos Home (ArtScroll), Vol. 2, Ch. 15, VI:E with note 50; Orchos Shabbos, Vol.1, 18:30 with note 48.)