Potatoes and Winter Squash
Antagonist Pair — Keep Apart
Two long-season heavy feeders competing for nutrients is a reasonable general principle, but we aren't aware of a trial measuring reduced potato or squash yield specifically from this pairing versus each grown separately. The more provable problem, honestly, is the physical one described below - winter squash's sprawl makes potato hilling and harvest genuinely difficult in practice, which is reason enough to keep them apart regardless of the nutrient question.
Mechanism: Nutrient Competition
Both crops are heavy feeders that pull hard on soil nitrogen and potassium through a long growing season - potatoes over 70-120 days of tuber bulking, winter squash over 80-110 days of vine growth and fruit sizing - and their root systems, while not identical in depth, both spread widely enough through a bed to compete meaningfully for the same nutrient budget when grown close together.
This is one of the more straightforwardly practical antagonist pairings on this site - the concern isn't a subtle chemical interaction, it's that winter squash's sprawling vines and potatoes' need for open, diggable soil are simply incompatible garden tasks happening in the same space.
The Physical Problem Outweighs the Nutrient One
Even setting aside whether nutrient competition between two heavy feeders is measurable, winter squash's vines will physically cross into a potato hill within a matter of weeks once established, tangling around the very soil you need to mound up and later dig through at harvest. That alone is reason enough to give winter squash its own dedicated space well away from any potato row, independent of whatever the actual yield-competition effect turns out to be.
Spacing
Winter squash needs a full 36-48 inches to sprawl, and that vine growth will happily cross into a potato row within weeks if planted anywhere nearby - there's effectively no spacing compromise that lets both crops keep their needed room in the same bed section.
Watch For
The bigger practical issue isn't nutrients at all - it's that potatoes need to be hilled with soil as they grow and eventually dug up from underneath, and a winter squash vine sprawling across that same ground makes both jobs far harder. Keep winter squash in a completely separate bed rather than trying to manage the overlap.
Frequently Asked Questions
How far apart do potatoes and winter squash actually need to be?
Far enough that squash vines won't reach the potato bed by midseason - given winter squash's 36-48 inch spacing and considerable vine spread, a separate bed entirely is the more reliable solution than trying to calculate a safe minimum distance within the same growing area.