Mowing
Mowing is allowed anytime during the first growing season until permanent cover is established. More than one mowing may be needed annually during the establishment period.
The first mowing should be done before July 1 or before weeds reach 12 inches in height. Iowa CRP Management advises mowing at about eight inches high and it should be done when temperatures are cooler to reduce competition for light, moisture, and nutrients.
If mowing cannot be done early due to reasonable events like rain, mow weeds as soon as weather conditions allow. If weeds have gone to seed, early mowing may be needed the following year, and more than one mowing may need to be done. If permanent grass is apparent (4-leaf stage) inside the weed cover, Iowa CRP Management will mow it to about twelve to fifteen inches to avoid tender new grass getting sun scalded. If permanent grass has not been found or is less than 4-leaf stage, the mow still can be eight inches.
Iowa CRP Management will stop mowing operations when more than one-fourth of the height of the seeded species is removed.
The use of post-emergent chemicals after seeding is limited to chemical label directions and grass seed mix planted. Wheat and/or cereal rye are also considered weeds in a CRP seeding and should be mowed prior to seed.