Zorei (Part 3) Opening Windows or Blinds Next to a Plant
THE LAWS OF SHABBAT
By Rav Yosef Zvi Rimon
Zoreia, Part III
VI) Opening Windows or Blinds Next to a Plant
In our previous shiurim, we have explored the melakha of zoreia in terms of adding seeds to soil or water to plants. What about adding less tangible elements to promote plant growth, e.g., light and air? Rav S.Z. Auerbach (Minchat Shlomo, Vol. I, 10:8) cites an issue raised by Rav Dr. Avraham Steinberg (Machazeh Avraham, OC, Ch. 52):
He had been asked, concerning a garden which has a glass roof, whether it would be permissible to open the roof on Shabbat so that the suns rays, which help the plants grow, may enter. He responds that since one does not manually act upon the sun or the plants at all, rather one merely removes the barrier which intervenes between the sun and the plants, it is only a gerama
However, in my humble opinion, this issue requires further study, based on what is explicitly stated on Shabbat 120b: one may not open a door facing a torch even at a time of normal wind conditions [which would not extinguish the flame], so that one will not come to do so at a time of abnormal wind conditions [which would extinguish the flame]. The logical implication is that if one were to open the door at a time of abnormal wind conditions, it would be a full melakha on a Torah level.
Thus, Rav S.Z. Auerbach believes that someone who opens windows so that the sun will cast light on the plants and improve their growth violates the prohibition of zoreia on a Torah level. He argues with Rav Steinberg, who sees in this only an act of gerama (causation). In light of his words, one should forbid rolling up the walls of the greenhouse so that plants will receive more light or more air.
Removing Impediments to Growth
What about removing elements which impede growth? In fact, Rav Auerbach (cited in Shemirat Shabbat Ke-hilkhata, Ch. 26, n. 30) himself allows rolling up the walls of the greenhouse if it is overheating, with the potential to harm plants and people; in this case, one wants to shed the heat. Since one does not seek an improvement to plant growth, but rather one removes the obstacle which may impede growth, there is room for leniency (provided that this is a one-time action and not a routine action in the maintenance of the greenhouse, see there).
However, the Yerushalmi (7:2) implies that the removal of elements which may impede growth, e.g., spraying operations to chase away worms (fumigation, chemical extermination, etc.), are forbidden on Shabbat on a Torah level. (Similarly, the Gemara on Moed Katan 3a indicates that fumigating is a tolada of zoreia.)
The Shevitat ha-Shabbat (Zoreia, 10) writes:
While it is true that, when it comes to many laws of the Torah, chasing away a lion i.e., the removal of a hazard is not considered an action, when it comes to Shabbat and the sabbatical year, we have found that chasing away a lion is considered an essential action.
In any case, even according to this view, the prohibition is only to remove extant dangers; there is no prohibition to perform actions which protect the plants from nascent dangers. Therefore, one may roll up the walls of the greenhouse before the temperature gets too high. (See Shemirat Shabbat Ke-hilkhata ibid.)
When One Does Not Intend to Improve Plant Growth
Until this point, we have dealt with a person who consciously intends to improve plant growth. What if one is not thinking about the plants? What if one simply wants to air out the room and the like? Is one allowed to open the window or the blinds? It would seem that this should be forbidden, because there is a pesik reisha, an inevitable result, that this act will benefit the plants, even if one does not intend to do so. However, Rav Tzvi Pesach Frank (Har Tzvi, OC, Ch. 133) rules that this is permissible, as does Rav Ovadya Yosef (Yechaveh Daat, Vol. V, Ch. 29):
Question: If one has seeds or flowers planted in pots in an apartment or on a windowsill, should it be halakhically forbidden to open the blinds or the windows of the apartment on Shabbat because the fresh air and heat from the suns rays will then help the plants grow? Or, despite this concern, should it be allowed?
Answer: There is reason to make a distinction and to allow this based on what the Rashba writes in his Chiddushim to Shabbat (107a) in the name of the Yerushalmi (13:6): one may lock his house on Shabbat in order to safeguard the house while the deer is inside, and there is no concern of trapping on Shabbat in this act, as long as one does not intend solely to keep the deer
The Avnei Nezer (OC, Ch. 194) explains the abovementioned words of the Rashba in the following way: closing the door alone one does not do anything to the body of the deer; it is a mere gerama Therefore, as they have said that the Torah forbids thoughtful labor it is only when one intends to trap the deer by the closing of the door that one is liable. This is not the case if one does not intend to trap a deer; it is considered a mere gerama, and the pesik reisha does not grant the gerama the status of an action
Even according to the Ran (38a, Rif), who writes that he rejects the abovementioned words of the Rashba in our case, one should be lenient, because opening the blinds or the windows is only removing an impediment. The fresh air and the heat of the suns rays are already present, and the blinds and the windows, when they are closed, prevent their penetrating into the apartment. Thus, opening them is the removal of an impediment, and consequently, one is not doing an action, but a mere gerama Adding the fact that one does intend for the seedlings to sprout, one should allow it
Furthermore, one may add another reason to be lenient that there is enough air in the apartment already, and by opening the blinds and the windows, one only adds air to it. Even without opening them on Shabbat, the seedlings would still sprout; and since there was no melakha like this in the Mishkan, to cause seedlings to sprout by opening blinds and windows, there is no prohibition from the Torah. The fact is that many of the halakhic authorities allow a pesik reisha of a rabbinic prohibition even though generally we follow the halakhic view of the Magen Avraham (314:5) and his camp, who forbid a pesik reisha of a rabbinic prohibition. Nevertheless, we have the view of the Rashba to be lenient; furthermore, there is nothing more than mere gerama in this case, as one does not make contact with the body of the seedling at all and everything is done by the removal of the impediment. Thus, there is great cause to be lenient
In conclusion, one may open the blinds or the windows of an apartment on Shabbat in order to let fresh air enter, even though there are pots in the apartment containing seeds or roses. (By the letter of the law, there is good reason to be lenient even in a case in which the pots are left on the windowsill itself, but nonetheless it is good to be stringent about this.) In any case, it is forbidden to open on Shabbat the glass covers of the greenhouses in which seeds and flowers grow when ones sole aim and intent is to benefit the seeds and flowers themselves, in order to promote their growth. May peace increase like a river for those who caution and those who are cautious.
According to this ruling, one may allow opening the window or the blinds as long as one does not intend to benefit the plants, since one can combine a number of reasons to be lenient:
1. According to the Rashba, one who locks his house and incidentally traps a deer inside violates no prohibition, as long as one has no interest in the deer and only seeks to protect the house. The reasoning of the matter is that one does not perform any action upon the body of the deer, and the act is considered a gerama. Even though if one were to lock the house with the aim of trapping the deer, this would be considered true trapping on a Torah level, and not gerama, this is only because the Torah forbids thoughtful labor (melekhet machshevet), and when a person plans that the closing of the door will help in trapping the deer, ones intent gives that action the status of trapping by hand. However, when a person has no specific intention of trapping, closing the door should not be seen as an action of trapping, but mere gerama. Similarly, since the person who opens the window does not do any action to the plants, and one does not intend at all to benefit them, one cannot see in his action an act of zeria, even if in practice, ones actions promote plant growth.
2. Even the Ran, who usually argues with the Rashba, can concede in our case, since the person does not bring the light or the air into the room in a proactive way, but rather removes the impediment preventing their entrance (windows or blinds). This matter is considered a mere gerama.
3. When the plant can grow in any case, and the person only improves its growth a bit, this does not constitute a Torah prohibition (except for the melakhot done in the Mishkan, such as watering) but rather only a rabbinic one (according to the Eglei Tal, Zoreia, 22). There are Acharonim who are lenient when it comes to the pesik reisha of a rabbinic prohibition.
In conclusion, it is forbidden to open windows or blinds in order to improve plant growth. However, it is permitted to open them if ones intention is to air out the house and the like, even if the matter will help the plant grow, because when one does not intend to make plants grow, an act such as this is not considered at all part of the melakha of zoreia.
 However, we have seen that in the view of Rav S.Z. Auerbach, this act is not considered causation, but rather direct action, however it appears that also according to his view, one may be lenient about this when one has no intent to improve the plants, since there are additional reasons to be lenient, as Rav Neuwirth (Shemirat Shabbat Ke-hilkhata 26:9) and the Orechot Shabbat (Ch. 18, n. 48) write.