Sweet Corn and Peanuts
Beneficial Pair — Good Match
Nitrogen fixation in peanuts is well documented agriculturally, and their long, warm-season timing genuinely overlaps with sweet corn's own 60-100 day window. What's less certain, as with the other legume-corn pairings here, is how much of that fixed nitrogen actually transfers to corn while both are still growing versus becoming available mainly after the peanut plants are done.
Mechanism: Nitrogen Fixing
Peanuts are legumes and fix nitrogen the same way beans and peas do, but their growth habit is different from either - a low, spreading groundcover that stays close to the soil for its entire 100-150 day season rather than climbing or bushing upward. Grown beneath sweet corn's tall stalks, peanuts function as both a season-long nitrogen source and a living ground cover shading the soil surface, a dual role most of the other corn-legume pairings in this reference only offer one half of.
Peanuts are the least commonly grown of the legumes paired with sweet corn on this site, but their low, spreading, season-long growth habit actually makes them a more complete match for tall corn than a bushier or climbing bean in some respects.
A Longer, More Complete Overlap Than Most Legume Pairings
Because peanuts take 100-150 days to mature - longer than sweet corn's own season in many cases - they're actively growing and fixing nitrogen for the corn's entire time in the ground, rather than finishing early like peas or needing a separate trellis like pole beans. The tradeoff is that peanuts need loose soil at the surface for their pegs to push pods underground, which limits how much foot traffic or cultivation you can do near the base of the plants once flowering starts.
Spacing
Peanuts need 6-10 inches and stay low to the ground their entire season, which makes them one of the easier legumes to interplant directly between sweet corn's 12-18 inch spacing without the trellis or climbing concerns that come with pole varieties of other beans.
Watch For
Peanuts have an unusual growth process worth knowing if you're growing them for the first time - after flowering, the plant's stems (called pegs) bend down and push the developing pods into the soil to mature underground, so the bed needs loose, workable soil at the base of the plant, not compacted ground from foot traffic between corn rows.
Frequently Asked Questions
Corn finishes weeks before peanuts do here - will harvesting the corn disturb peanuts still maturing underground?
It can, if you're walking heavily between rows. Peanut pods are maturing just under the soil surface for weeks after corn stalks are ready to come down, so treat that harvest walk-through carefully rather than assuming the bed is done simply because the taller crop is out. Cutting corn stalks at the base instead of pulling them disturbs less of the surrounding soil where peanuts are still finishing.