Hydroponics and Greenhouses

One of the greatest challenges in kashrus for Rabanim Hamachshirim today is protecting consumers from tolaim. This task is very daunting and difficult since insects are by nature highly pervasive. One method that has become popular, especially in Eretz Yisroel, is to grow vegetables in greenhouses. Also known as glasshouses or hothouses, their objective is to provide a pest-free environment. Farmers working in conjunction with Rabbanim Hamachshirim have successfully perfected this method, which has proven to be an invaluable tool in the fight against tolaim in produce.

A greenhouse is typically composed of glass or plastic walls and ceiling. The structure’s makeup allows it to absorb and trap solar radiation, and thereby heat the plants growing inside. However, harmful radiation from the sun does not pass through the building. Greenhouses have been especially crucial in providing controlled environments for farmers in areas that may have exceedingly hot or cold climates, which otherwise would be hostile to agriculture. These controlled environments all have special requirements to protect plants from unwanted pests and outdoor elements. Provided that these requirements are properly followed, the houses serve their intended purpose.

It is very important to note that produce grown in a greenhouse or hothouse can not automatically be assumed insect-free. Farmers have a much greater tolerance level when it comes to tolaim than what is allowed by proper halachik standards. For example, the US government allows averages of up to 60 insects per 100 grams in frozen broccoli, and up to 50 insects per 100 grams of frozen spinach (See Food, Drug, and Cosmetics Act 402 (a)(3)). The presence of insects in vegetables is not viewed as a health hazard, and to the contrary they are considered a good source of protein. Very often farmers are focused on the hostile natural elements of the environment, and have little concern when it comes to insects. It is therefore necessary for consumers to make sure that greenhouse grown produce, which ordinarily could contain bugs, has an acceptable hechsher. The purpose of the hechsher is to monitor the practices of the greenhouse, and ensure that the appropriate precautionary measures are taken to eliminate the presence of tolaim. These measures include, using certain pesticides, netting, and ensuring that the structure is properly sealed and contained from insects who may wish to enter.

When proper precautionary measures are implemented at a greenhouse under the supervision of an acceptable hecsher, it is assumed that its vegetables do not require checking for tolaim. Rav Shternbuch was once asked what the halachik basis for this assumption is, since there are certain types of vegetables that are assumed to have insects and should require examination Rav Shternbuch responded (see Teshuvos VeHanhagos 3:252) that since incidents of infestation in these hothouses are very rare, they do not require inspection. However, he writes that the same assumption does not apply to factories with advanced washing systems. The difference between the two scenarios is that a hothouse environment eliminates the presence of insects, while a washing system merely reduces infestation. In the latter case, he writes that there is still an obligation to inspect and ensure that insects were properly removed during the washing.

There are different ways produce can grow in a greenhouse. The standard way is to grow plants in soil, which has been the growing environment since time immemorial. However, in the 1800s it was first discovered that plants could also be grown in water containing certain nutrients. This practice has been perfected over time, and is known today as hydroponics.

Vegetables grown through hydroponics present a very interesting question about their bracha rishonah.
On one hand, vegetables typically fall into a category of something that is grown in the ground. By definition it seems that the proper beracha of any vegetable should be borei pri ha’adamah. On the other hand, these vegetables are not grown in the ground, but rather in water, and perhaps the proper beracha should be shehakol. This question has been discussed by contemporary poskim, who have taken different positions on the issue. Rav Shmuel Wosner shlita (see Shut Shevet HaLevi 1:205) and Rav Moshe Shternbuch shlita (see Teshuvos VeHanhagos 2:149) have ruled that the proper bracha rishonah should be borei pri ha’adamah. The rationale of both poskim is that as a category all vegetables specifically require this beracha. The notion of taking two broccoli florets, one grown in the ground and the other in water, and requiring two different berachos is not tenable. Therefore, all vegetables, regardless as to where they were grown require the same beracha, which is ha’adamah.

Rav Ovadia Yosef shlita wrote a teshuva about this question as well (see Yechaveh Da’as 6:12). In his responsa, Rav Ovadia cites many sources that the proper beracha rishonah for vegetables grown in water should be shehakol, including prominent ashkenazic poskim. Firstly, the Chayei Adom (51:17) writes that the proper beracha rishonah to recite on bread processed from grains grown in a flour pot is shehakol, not hamotzi Although the Rashash in his commentary on Pesachim (36b) disagrees, based on the Chayei Adom it seems that hydroponic vegetables would be shehakol. Secondly, poskim including the Chazon Ish zt’l and Rav Yechiel Michel Tuchachinsky zt’l ruled that it is permitted to grow produce in water during the Shemittah year. It would therefore appear that these types of vegetables should not be considered as growing from the ground, and borei pri ha’adamah would be a misnomer. It would seem more appropriate to compare hydroponic vegetables to mushrooms. Mushrooms are not grown from the ground and the proper beracha is shehakol (see Berachos 40b). Thirdly, there is a halachik discussion about what beracha rishonah was recited by Bnei Yisroel on mun in the midbar. Many authorities were of the position that hamotzi was not recited on mun since it fell from the sky, even though it was a form of bread. According to this opinion it would seem that vegetables that are not grown in soil should not require ha’adamah. Rav Ovadia concludes that the proper beracha should be shehakol, although ha’adamah is also acceptable bedieved.

Consumers should be aware that vegetables grown in soil at a greenhouse, or through hydroponics, could still have exposure to flies. These vegetables might still require washing prior to use. However, it is sufficient to remove flies with just a regular washing under a stream of water. This is true even though these products are under hechsher. If washing is required, it will state so on the packaging. Assuming that the greenhouses follow proper procedures, under the careful watch of a reliable hechsher, the most bothersome and pesky insects such as aphids, thrips, leaf miners, etc. will not be a problem.

As always, a Rov should be consulted to determine whether a hechsher is acceptable.


OU Kosher Staff