In Vayikra 19:19 we are given the commandment “not to plant your field with mixed seeds”. The Gemarah (Shabbos 84b) explains that seeds which are side by side need to have a three tefach distance between the rows. However, if they do not share a side (even if they are close diagonally) there does not need to be any distance placed between them.
Here are some examples of how this works:
If there is a row of carrots and a row of beets parallel to each other then the rows need to be at least 3 tefach apart.
If there is a row of carrots and a row of beets perpendicular to each other and one row is near the side of another row then the closest seed of each seed has to be at least 3 tefach apart.
The exception to the rule in figure 2 is when the two lines meet at a corner. If the two lines are perpendicular to each other and they ONLY meet at a corer then they do NOT need to be 3 tefach apart.
How can you fit the following in to a field that is in a 6 x 6 tefach square?
A row of parsnips 5.9 tefach long
A row of carrots 5.9 tefach long
A row of beets 5.9 tefach long
A row of onions 5.9 tefach long and