Mishnayos Kilayim Perek 7 Mishnah 1

המבריך את הגפן בארץ – and it passes the sinking outside of six handbreadths, for within six handbreadths, even that there is dirt upon it for three handbreadths, it is prohibited, because it is the tilling of an individual vine.

לא יביא זרע עליה [the underground vine] – but from the side, it is permitted, for when one seeds to the sides, they don’t take root, but rather that they make the crushed earth and it affects the foundations of the wall when they are sown next to it, but their roots grow from the side. But the reason that one should not bring seed upon the sunken vine even outside of its tilling is because the vine is soft and the roots of the seeds enter the vine and there is the sinking of a vegetable in the tree, but the rest of the trees that are not soft is permitted.

אפילו הבריכה בדלעת או בסלון (if in sinking a vine he conducted it through gourd shells or through a pipe – so that it could draw no nourishment from the ground which it passed) – that he inserted the vine within the gourd or within the pipe, it is prohibited because the roots of the seeds perforate and penetrate until the vine when there are not three handbreadths of dirt upon it. And because the seeds in a gourd is not forbidden as for example, that the gourd is dry.

סלון – it is a water pipe and a tube/spout or one pipe. But especially in an earthenware pipe/tube, we are speaking of a metal tube that does not require dirt of three handbreadths.

הבריכה בסלע – in a hard [rock], for a soft rock [penetrates] and is opened from the roots.

הארכובה שבגפן – a vine that is curved and bent on the ground and returns and is put up like a kind of curved knee, when hey come to measure six handbreadths that are the tilling of the individual vine, hey measure from the second root from the place where it returns and stands up straight. But these words apply when the first root is not seen but rather it is similar to a tree when it is planted in the place of its bending, but if the first root appears that it is the root of the curved vine, we don’t measure other than from the first root.