Buying fruit trees in the US when the rootstock-scion pair is unknown
Question
Hi, I was hoping you could help me. Any of the box stores and vendors that sell fruit trees in the United States do not list their rootstock. My understanding is that at times they can use various different rootstocks that are often not the original min. How concerned do I have to be about this when purchasing these trees?
Answer
You are correct: nurseries sometimes use rootstocks from a different halachic species than the scion, and when the scion-rootstock combination is not listed, it is often impossible to determine its status.
How concerned should you be?
The prohibition of kilei ilan (grafting different species) applies even outside of Israel. If a tree was grafted in a forbidden manner, it may not be planted or tended to—it must be uprooted.
What can be done when the rootstock is unknown?
Some fruit trees are typically grafted only onto rootstocks of the same halachic species. In such cases, there is no concern of kilayim, and they may be purchased without issue—even if the rootstock isn’t specified.
For citrus trees, rootstocks are generally other citrus varieties. However, there is a machloket (halachic dispute) as to whether all citrus varieties are considered the same species. When there is either a factual doubt (what species was used) or a halachic doubt (whether different types of citruses grafted together constitutes kilayim), you may have a non-Jew plant the tree, after which it is permitted to maintain.
In contrast, some trees are regularly grafted onto rootstocks of a different species, and if so, they may not be planted or tended to at all (watering, fertilizing, etc.), as noted above.
Are you asking generally, or do you have specific types of trees in mind?
In the meantime, please see this list of common scion-rootstock pairs. Trees that do not involve any grafting or involve only halachically acceptable grafts can be purchased with confidence—even when the rootstock is unspecified.