A word to the wise who want to plant legumes by natural reseeding: refrain from mowing and using it for grazing in the meantime. Let it grow undisturbed.
It’s typical for many farmers, landscapers or highway departments to use either annual or perennial legumes not only for grazing but also for pollinator attraction, erosion control or beautification. But first they need to determine their primary purpose in planting.
“Most annual legumes are planted in the fall, grow vigorously the following spring and go into the reproductive phase in early summer,” said Dirk Philipp, associate professor of animal science at the University of Arkansas System Division of Agriculture. Annual legumes depend on seed setting and shedding so that new stands can develop.
“Seed setting takes place in mid- to late spring, but when legumes are grazed repeatedly during that time, reproductive tillers and seeds cannot develop any more,” Philipp said. “The plant basically runs out of time.”
To get new stands each year from the annual legumes, Philipp recommends letting a “seed bank” develop in the soil by leaving the plants undisturbed with no grazing. If grazing takes place early enough, it’s possible that some seeds may still develop but it’s better to leave the stand alone no later than end of March.
Annual legumes such as crimson or arrowleaf clovers can easily be established in flood plain areas near streams where infrequent grazing should be the rule. Philipp said it may take only a year or two to start a clover seed bank, but it’s best for long-term development to leave the legumes alone as long as possible. After a few years, grazing can take place each spring. By then there are enough seeds in the ground for reliable natural reseeding.
Perennial legumes don’t need seed development to persist, but some species such as white clover and red clover benefit by deferred grazing. For red clover, Philipp recommends no grazing or mowing in August and early September when flowering and seed setting takes place. White clover can generally be grazed or mowed as it continuously flowers, but it benefits if grazing is deferred for a period of time before fall in some years to slowly develop a seedbank as well.
“Soil tests for a fertilization strategy are mandatory to achieve optimum plant health and seed development,” Philipp said. Legumes utilize relatively high amounts of phosphorous and potassium, so attention should be paid to the soil tests.