Grain Sorghum Planting Guidelines
Sandra Wick, Crop Production Agent
Producers are busy in the field planting corn and soybeans, however, it won’t be long and it will be time to plant grain sorghum. Well let’s hope that Mother Nature helps us out and keeps rain in our forecast! Our wheat continues to need moisture and our spring row crops need it to germinate and continue to develop.
Let’s start with the Sorghum population or the seeding rate. Recommendations can vary significantly depending on your annual rainfall. So for north central Kansas the recommended seeding rate is approximately 35,000 to 64,000 seeds per acre with final stands of 25,000 to 45,000 plants per acre. Because of sorghum’s ability to respond to the environment, final stands can vary at least 25%, depending on the expected growing conditions, without significantly affecting the yields. Lower seeding rates help minimize the risk of crop failure in dry environments. Sorghum can compensate for good growing conditions by adding tillers and adjusting the head size, but yields can be reduced in a dry year if populations are too high. Sorghum will tiller more readily in cooler temperatures and less readily under warm conditions. Higher seeding rates also should be used when planting late and should be increased by about 15-20% if planting in late-June or even later. About 65-70 percent field germination is a good general rule to use. Row spacing goes hand in hand with the seeding rate. Using narrow row spacing, such as 15-inch compared to the traditional 30-inch row spacing, is significantly dependent on the environmental conditions especially moisture.
A summary of research data performed at KSRE in the last several years has confirmed that the optimum planting date for maximizing yields will be around early June. Still, the decision related to the optimum planting date should be timed so plants have the best possible chance of avoiding the hot, dry weather at the flowering stage, but can still have sufficient time to mature before the first frost.
Producers are busy in the field planting corn and soybeans, however, it won’t be long and it will be time to plant grain sorghum. Well let’s hope that Mother Nature helps us out and keeps rain in our forecast! Our wheat continues to need moisture and our spring row crops need it to germinate and continue to develop.
Some of the main planting practices affecting yields in sorghum are: row spacing, seeding depth, seeding rate/plant population, planting date, and hybrid maturity.
Sorghum plants can compensate and adjust to different environmental conditions through adjustments in the number of tillers, head size, and the final seed weight. For sorghum, the final number of seeds per head is the plant component that varies the most; and thus has more room for adjustment than the other plant components (seed weight and number of tillers).
Let’s start with the Sorghum population or the seeding rate. Recommendations can vary significantly depending on your annual rainfall. So for north central Kansas the recommended seeding rate is approximately 35,000 to 64,000 seeds per acre with final stands of 25,000 to 45,000 plants per acre. Because of sorghum’s ability to respond to the environment, final stands can vary at least 25%, depending on the expected growing conditions, without significantly affecting the yields. Lower seeding rates help minimize the risk of crop failure in dry environments. Sorghum can compensate for good growing conditions by adding tillers and adjusting the head size, but yields can be reduced in a dry year if populations are too high. Sorghum will tiller more readily in cooler temperatures and less readily under warm conditions. Higher seeding rates also should be used when planting late and should be increased by about 15-20% if planting in late-June or even later. About 65-70 percent field germination is a good general rule to use. Row spacing goes hand in hand with the seeding rate. Using narrow row spacing, such as 15-inch compared to the traditional 30-inch row spacing, is significantly dependent on the environmental conditions especially moisture. 
A summary of research data performed at KSRE in the last several years has confirmed that the optimum planting date for maximizing yields will be around early June. Still, the decision related to the optimum planting date should be timed so plants have the best possible chance of avoiding the hot, dry weather at the flowering stage, but can still have sufficient time to mature before the first frost.
Seed placement or planting depth is also a critical factor in sorghum production. Optimum seed placement for sorghum is about 1-2 inches deep. Shallower or deeper planting depths can certainly affect the time between planting and emergence thus affecting early-season plant uniformity.
Lastly, but certainly not the least is hybrid selection. The selection of sorghum hybrids should be based not only on maturity, but also on other traits such as resistance to pests, stalk strength, head exertion, seeding vigor, and overall performance.
If you have more questions on grain sorghum, give me a call at any of our Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center.
Be sure and mark your calendars for our annual Post Rock Extension District Wheat Plot Tour scheduled for Tuesday, May 29 with five stops around the district. There will be two “legs” to our tour with an eastern and western tour. The western tour will begin at 9:00 a.m. in Smith County and the eastern tour will begin at 10:30 a.m. in Jewell County. The tour will conclude in Mitchell County at the KSRE Replicated plot at 4:30 p.m. located south of Beloit on Hwy. 14 to X Road (the Hunter Road), then 4 ½ miles west, on the north side. A meal will follow the tour which will be held at the Fletchall house close to the plot. A meal or refreshments will be served at each of the stops thanks to our agribusiness sponsors around the area. For more details call any of our Post Rock Extension District Offices in Beloit, Lincoln, Mankato, Osborne or Smith Center. Hope to see you there! Have a GREAT day!
Post Rock Extension District of K-State Research and Extension serves Jewell, Lincoln, Mitchell, Osborne, and Smith counties. Sandra may be contacted at swick@ksu.edu or by calling Smith Center, 282-6823, Beloit 738-3597, Lincoln 524-4432, Mankato 378-3174, or Osborne 346-2521. Join us on Facebook at “Post Rock Extension”. Also remember our website is www.postrock.ksu.edu and my twitter account is @PRDcrops.
