Published Feb 27, 2015

RESEARCH REPORT: Summer Squash Following Winter Rye

By Stefan Gailans

Cover crops are not just for our row crop farmers! Indeed, a number of fruit and vegetable growers use cover crops to suppress weeds, conserve moisture and build soil fertility. Last summer, Mustard Seed Community Farm near Ames explored how a winter rye cover crop affected summer squash production in a report entitled: Summer Squash Following Winter Rye.

Their goal was to use cover crops to manage weeds that compete with summer squash and to reduce labor costs associated with weed management. Mustard Seed Community Farm put in a winter rye cover crop in Fall 2013 and chose an “early” and “late” termination date in Spring 2014 to achieve different levels of rye biomass before seeding summer squash. The hypothesis was that a later termination would result in greater rye biomass that would then serve as a mulch for the summer squash and physically suppress weed seed germination.

Alice McGary and Nicholas Leete

Nicholas Leete and Alice McGary of Mustard Seed Community Farm implemented the trial.

Among the key findings:

  • The late-terminated rye cover crop produced more spring biomass and reduced weed pressure relative to the early-terminated rye cover crop. This also resulted in less hand-weeding in the late-terminated rye cover crop treatment.
  • The late-terminated cover crop, however, also reduced summer squash germination and negatively affected summer squash yield compared to the early-terminated cover crop.

This trial will be conducted again in 2015 on Mustard Seed Community Farm. For more information on this study, contact Liz Kolbe at

Funding for this project was provided by the Ceres Foundation. The full project report can be found here.