Planting Warm Season Annual Grasses

Plantings of warm season annual grasses can be made in the spring as soon as the soil temperature (at 2 in. depth) warms to 65º F and can be planted as late as July without a yield penalty (Table 1). Seed can be broadcast or drilled in narrow (< 15 in.) or wide (up to 36 in.) rows. Seed should be planted at a soil depth of ½ - 1 inch. Ideally, summer annual grasses should be established on well-drained, fertile soils with good water-holding capacity.

Higher seeding rates may help to decrease stem size, but it is unlikely that this will be valuable enough to compensate for the expense of the higher seeding rate. Further, sorghums that have been seeded at higher rates will often have more lodging problems, especially relative to dwarf pearl millet stands.

Even out the grazing supply over the summer by making multiple plantings. Two plantings made four to six weeks apart provide good quality forage throughout the summer. Plantings made in early June will be in peak production when April plantings are starting to decline in productivity. If plants become stemmy from selective grazing, mechanically clip them to a height of 10 – 12 inches and fertilize with N. With good grazing management, clipping may not be necessary.

Photoperiod-sensitive sorghum x sudan and foragesorghum cultivars are available. These varieties are capable of sustaining more consistent growth over a longer-growing season because they remain in a vegetative stage late into September (until daylength is less than about 12 hours and 20 minutes). This trait may negate or lessen the need for staggered plantings. Otherwise, these varieties are generally managed (planted, fertilized, etc.) in the same way as conventional cultivars. However, some research indicates that the quality of photoperiod-sensitive varieties is lower than the conventional cultivars. Reports from other states indicate that some companies are claiming their cultivars are photosensitive when they merely mature later.

LV = Limestone Valley/Mountains Region; P = Piedmont Region; C = Coastal Plain Region.
NR = Not recommended

Dr. Dennis Hancock
Forage Extension Specialist
Crop & Soil Sciences Dept.