Not Quite Bean Logic: Leafless Cultivars and the Double-Row Trellis
Peas share a bush-vs-vining split with beans, but it isn't identical. Peas run noticeably tighter in-row (1-3 in. versus beans' 2-8 in.), and a genuinely pea-specific option exists that beans don't have: leafless or semi-leafless ("afila") cultivars, bred so tendrils replace leaflets. Penn State Extension confirms these "may be better able to stand without a trellis, because the tendrils tangle themselves into a mass" -- a real, extension-documented trait with no real bean equivalent.
The double-row-per-trellis planting pattern is also a distinctly pea-oriented technique: rather than a single row along one support, tall peas are commonly sown as two rows straddling one central trellis, so both rows can climb the same structure from opposite sides.
Timing is the other genuine difference from beans, even though it isn't strictly a spacing question: peas are a cool-season crop, planted very early in spring (or again in late summer for a fall crop), unlike beans, which need warm soil and go in after the danger of frost has passed.
Why Spacing Matters for Peas
Bush peas planted too close together lose the self-supporting structure that makes them low-maintenance in the first place -- overcrowded plants lodge (fall over) into each other rather than standing upright as a loose thicket.
For trellised types, spacing interacts directly with the trellis itself: plant too far from the support and vines struggle to reach it; plant the two rows of a double-row planting too close together and you lose the airflow through the middle of the trellis that helps prevent powdery mildew, a common late-season pea disease.
