Growing Sorghum: Guide From Planting To Harvesting

Sorghum Climate And Soil Requirements

Sorghum can adapt to different growing conditions. Its drought resistance makes it an ideal crop for semi-arid growing regions prone to water scarcity, where most other crops struggle to grow.

What Climate Does Sorghum Grow In?

This warm-season crop can grow well in high temperatures and is hence well-suited to hot climates. At 59°F (15°C), most seeds will germinate within 10 to 12 days, while higher temperatures of 77–82°F (around 25–28°C) can lead to faster emergence, typically within 5 to 6 days. Temperatures below 15°C (59°F), as well as water scarcity, could impede germination and early growth, and temperatures of 77–86°F (25–30°C) throughout the growing season promote plant growth and boost yields.

While the crop needs full sun to grow healthy, it can tolerate some shade, especially in scorching climates. Plant sensitivity to light varies by growth stage. It can handle high temperatures and intense sunlight during the vegetative stage but may become more sensitive during the reproductive stage (e.g., during flowering). Too much sun, especially combined with a dry spell, during this time can negatively impact flower formation and grain yield.

To fully realize the potential of your crop with minimal effort, choose fields with the optimal combination of climatic conditions. EOSDA Crop Monitoring provides all the data you need to select a field, from temperatures and solar radiation to precipitation and evapotranspiration, over decades. Plus, you can get weather forecasts up to 14 days in advance, so you can shade your plants or water them before any stress occurs.

What Soil Does Sorghum Grow In?

The crop grows best in loamy soils that drain well. While it can handle sandy soil, it does better where there’s clay in the lower layers to hold water. The plant won’t get hurt if the field floods briefly, but longer waterlogging will impact your yield. The optimal soil pH for sorghum is between 5.5 and 7.5. Unlike many other grains, it can handle some salinization and alkalinity but struggles in acidic conditions. Before planting, plow deep and work in some compost or aged manure to improve your soil.

How To Prepare Pre-Planting And Plant Sorghum

When choosing a variety to grow, assess the variety’s adaptability to local conditions. About a month before the planned sowing dates, prepare the field to ensure good seed-to-soil contact and moisture retention. Plant at warm temperatures and try to space seeds at a uniform distance and depth.

Choosing Sorghum Varieties To Grow

The first thing to consider when choosing a type of sorghum to grow is its end use. Depending on the end use, there are three options to consider:

• grain (milo) to grow for their seeds, primarily used as food for humans and cattle;
• forage to grow for livestock feed due to their high biomass yield and nutritional quality;
• sweet to grow for their high sugar content and then process into syrup or ferment into ethanol.

Once you have narrowed down your list of varieties by the end use, it’s time to think about how well they’ll do in your growing regions. This includes factors like sorghum soil requirements, drought tolerance, pest and disease resistance, and its average growing season. Another important consideration is yield potential. Talk with local agricultural experts and use precision farming platforms to choose the best variety to plant.

Land Preparation

Successful sorghum growing starts with proper field preparation. First, clear all plant residue, debris, and weeds. Follow with deep plowing, 8–12 inches (20–30 cm), to break soil compaction. Next, harrow to achieve uniform soil texture. In wet-prone areas, construct elevated rows (ridges) for better drainage. Schedule these operations at least one month ahead of planting sorghum.

Best Ways To Plant Sorghum

Late spring to early summer, ideally after the last frost, is when it’s best to plant sorghum. Ensure the soil temperature reaches a minimum of 60°F (15°C) for successful germination. Late planting might cause drought stress and reduce the time available for plants to develop productive tillers. In warmer regions, sorghum planting can also occur from September to early October to grow as a second-season crop.

Seeds can be sown either by broadcasting or drilling. Even though broadcasting is much faster, particularly over vast areas, it doesn’t work well for commercial crop growing because of uneven seeding rates. Drilling involves using a seed drill to place seeds directly into the soil at a specific depth and spacing. This method ensures that seeds are planted uniformly and at the correct depth, which is crucial for optimal germination.

Sorghum planting spacing influences how plants compete for resources, how successfully they suppress weeds, and how convenient it is to carry out routine agricultural operations. To balance these parameters, stick somewhere between 10 and 30 inches (25 and 75 cm). The optimal planting depth for sorghum seeds is typically between 1 and 2 inches (2.5 and 5 cm). In sandy soils, deeper planting may be acceptable, while in heavy soils the depth should not exceed 1 inch (2.5 cm) to ensure proper seed-to-soil contact and quick germination.

Care For Sorghum During The Growing Season

Sorghum is a moderate to heavy feeder, particularly in terms of its nitrogen requirements. So, you’ll need to apply NPK fertilizers to achieve the desired yields. And to protect those yields from threats, monitor for sorghum diseases, weeds, and insects regularly and implement integrated pest management strategies.

Sorghum Fertilizer Recommendations

Nitrogen (N), phosphorus (P), and potassium (K) should be the primary nutrients applied based on the results of soil tests. Average recommended rates are 71–107 lb/ac (80–120 kg/ha) of nitrogen and 36–53 lb (40–60 kg/ha) of both phosphorus and potassium. To improve nutrient uptake and decrease runoff, it’s best to apply P&K fertilizers for sorghum at planting and divide N fertilizers between planting and the early stages of plant growth.

Satellite technology can help you put fertilizer exactly where your sorghum needs it. The process is simple: VRA (variable rate application) maps based on cloudless satellite images show which parts of your field have enough plants growing and which areas have fewer. You can then adjust your fertilizer amounts accordingly — more for sparse vegetation, less for abundant. VRA maps by EOSDA Crop Monitoring come in different file formats compatible with fertilizer spraying and broadcasting machines.

Sorghum Weeds, Pests, Diseases And Their Control

Commercial sorghum farming faces three major threats: weeds, pests, and diseases. Weeds pose the greatest risk during the first one to one and a half months after emergence, directly competing with young crops. Although narrower spacing — 12–20 inches (30–50 cm) between rows — naturally suppresses weed growth, pre-emergence herbicides and mechanical weed control are often necessary.

Key pests include sorghum midge, aphids, shoot flies, earhead bugs, and stem borers. Plants are particularly vulnerable during flowering and grain fill. Pest damage often goes beyond yield reduction; for example, midge and earhead bug feeding results in distorted, lightweight seeds that bring lower market prices.

The crop suffers from over 50 diseases, from root rot to head mold ^{Thakur, R. P., Reddy, B. V. S, Mathur, K. (Eds.). 2007. Screening Techniques for Sorghum Diseases. Information Bulletin No. 76. International Crops Research Institute for the Semi-Arid Tropics.}. Anthracnose, downy mildew, charcoal rot, and grain mold are particularly damaging. Modern space-derived vegetation monitoring helps crop producers detect these issues early — in EOSDA Crop Monitoring, they can track crop health using various indices like NDVI through Sentinel-2 imagery (10 m resolution, 3–5 day updates) or Planet’s imagery (3 m resolution, daily updates) for even more precise threat mapping. This technology integrates seamlessly with traditional practices like growing resistant varieties, crop rotation, and fungicide applications to grow crops safely.

How Long Does Sorghum Take To Grow?

Temperature directly affects how long the crop grows. In warm conditions above 68°F (20°C), early varieties sprint to harvest in 90–110 days, while medium varieties in 110–140 days. But when temperatures drop below 20°C, the growing clock slows significantly — each half-degree cooler adds 10–20 extra growing days. Growing periods stretch to 250–300 days when temperatures average 15°C ^{Sorghum. Food and Agriculture Organization of the United Nations.}.

When And How To Harvest Sorghum

Sorghum harvest usually occurs during July–August (first-season crop) or November–January (second-season crop) when kernels reach physiological maturity. Key indicators of maturity include a visible black spot at the kernel base and 20–25% grain moisture content. Grain combines can effectively handle sorghum harvesting when calibrated to separate out leaves and stalks.

The final step is drying your grain to less than 13% moisture content before storing it in a well-ventilated facility. Under normal conditions, grain has a storage life of 6–12 months, or possibly longer, giving crop producers the leeway to manage market fluctuations and find suitable buyers.