Fava beans are dual-purpose! As a cover crop, fava beans have one of the highest nitrogen-fixing rates, and the large, deep roots break up even heavy clay and compacted soil. For maximum nitrogen, harvest crop at peak bloom and work back into the soil to increase level of organic material. Seeds can be sown in temperatures as low as 35°F, and plants are fast growing and very cold hardy. Fava sown after the summer solstice or in late summer/fall will produce tall plants but will not produce flowers. CAUTION: People deficient in an enzyme called glucose-6-phosphate dehydrogenase (G6PD) should not handle seeds, consume fava beans, or inhale its pollen.