Nasturtium and Collard Greens
Beneficial Pair — Good Match
Among trap-crop claims on this site, nasturtium's aphid-drawing habit is unusually well supported. The extended-season reasoning for collards specifically - more standing time means more opportunity for aphid buildup - is a straightforward practical inference from collards' known growing habit rather than something needing its own separate trial.
Mechanism: Trap Cropping
The mechanism here is the same one behind this site's other nasturtium-and-brassica pairings - aphids genuinely prefer nasturtium foliage over brassica leaves - but collards' growing habit changes the timeline involved: collards are often grown as a cut-and-come-again crop, harvested leaf by leaf over months rather than all at once, which gives aphid colonies far more time to build up on a standing collard planting than on a brassica harvested in a single pass.
Collard greens are grown differently from most brassicas on this site - instead of one head or curd harvested at a single point, outer leaves are picked continuously over an extended period, sometimes months, which changes how long-term pest pressure actually plays out.
A Longer Season Means More Time for Aphids to Build Up
A crop harvested all at once has a defined window where pest pressure matters. Collards, picked leaf by leaf over an extended stretch, give aphid populations more time to establish and grow if nothing is diverting them elsewhere. That makes a season-long nasturtium planting more relevant here than it might be for a brassica that's in and out of the ground in under two months - the trap crop needs to keep working for as long as the collards are still being harvested.
Spacing
Collards' substantial 18-24 inch spacing and broad leaves leave real room for a nasturtium border along the row's edge without shading it out the way a denser crop's canopy eventually would.
Watch For
Because collards can stay productive for months, especially in mild climates where they're harvested well into winter, refresh or reseed the nasturtium planting partway through the season if the original planting fades - a spring-sown nasturtium won't necessarily still be vigorous by the time a collard planting is still going in late fall.
Frequently Asked Questions
Should I plant new nasturtium partway through a long collard harvest season?
It's worth considering if your original planting has faded - nasturtium isn't a particularly long-lived annual, and collards' extended cut-and-come-again harvest can easily outlast a single nasturtium planting's useful life, especially in a mild-winter climate where collards keep producing into the cold months.