How Tall Does Sorghum Grow

If you’re planning to grow sorghum, one of your first questions is likely, ‘how tall does sorghum grow?’ The maximum height achieved by this versatile plant can vary dramatically, from a modest 3 feet to towering over 16 feet tall, depending on several key factors.

Understanding this range is crucial for planning your garden layout, ensuring proper support, and choosing the right variety for your needs. Whether you’re growing it for grain, syrup, or as a stunning ornamental grass, knowing its potential size helps you succeed.

This is the core question. The simple answer is that sorghum can grow anywhere from 3 to over 16 feet in height. However, most common grain sorghum varieties cultivated by gardeners and farmers typically reach between 4 to 7 feet tall at maturity.

The extreme ends of the spectrum are fascinating. Dwarf varieties, bred for easier mechanical harvesting, might only reach 3 feet. On the other hand, some traditional heirloom sorghums, especially those grown for making sorghum syrup, can soar to heights of 8 to 16 feet. The world record for sorghum height is over 20 feet, but that’s an exceptional case under perfect conditions.

Key Factors That Influence Sorghum Height

Why such a huge difference? A sorghum plant’s final height isn’t random. It’s directly influenced by genetics, environment, and your care. Here are the main elements that determine how tall your sorghum will get.

1. Variety and Genetics

This is the most important factor. The seed you plant has a built-in height range.

Grain Sorghum: Often called milo, these are usually shorter, ranging from 3 to 5 feet. They put more energy into seed head production.
Sweet Sorghum: Grown for its sugary stalk juice to make syrup, these varieties are the giants, commonly reaching 8 to 12 feet.
Broomcorn: Grown for its long, fibrous panicles used for brooms, these can also get quite tall, often 6 to 10 feet.
Forage Sorghum: Bred for animal feed, these are typically tall and leafy, often 6 to 10 feet high.

2. Soil Quality and Nutrition

Sorghum is known for its drought tolerance and ability to grow in poorer soils, but fertility still impacts height. Rich, well-drained soil with good organic matter will support maximum growth. A lack of key nutrients, especially nitrogen, can severely stunt plants. However, to much nitrogen can cause excessive leafy growth and lodging (falling over) without increasing yield meaningfully.

3. Water Availability

While sorghum is remarkably efficient with water, its height is directly linked to moisture. Consistent moisture, especially during the vegetative growth stage before flowering, encourages taller stalks. Prolonged drought will limit cell expansion and result in shorter plants.

4. Sunlight and Temperature

Sorghum is a sun-loving, warm-season crop. It requires full sun—at least 6 to 8 hours daily—to reach its potential. More sun generally means more growth. It also thrives in warm temperatures, with optimal growth occurring between 77°F and 95°F. Cooler weather will slow growth and reduce final height.

5. Planting Density

How close you plant your sorghum seeds matters. Plants spaced too closely will compete fiercely for light, water, and nutrients. This competition often results in taller, spindlier plants as they stretch for sunlight, but they may be weaker and more prone to falling over. Wider spacing allows for sturdier, sometimes slightly shorter plants with larger tillers (side shoots).

How to Measure Your Sorghum’s Height

It’s helpful to know how to accurately track growth. Height is typically measured from the base of the plant at soil level to the tip of the main stalk’s panicle (seed head).

Wait for a calm day to prevent the plant from swaying.
Use a tall, rigid measuring stick or a tape measure attached to a pole.
Gently hold the main stalk upright without pulling it.
Record the measurement from soil line to the very top of the seed head.

Managing the Height of Your Sorghum

You can exert some control over how tall your sorghum grows through simple gardening practices.

Choosing the Right Variety

Always start by selecting a variety whose typical height matches your goal and garden space. Seed catalogs and packets will list this information. If you have a small garden or want to avoid staking, choose a dwarf or standard grain sorghum. If you want a dramatic backdrop or are making syrup, choose a tall sweet sorghum.

Adjusting Planting Time and Spacing

Later plantings in the season may result in slightly shorter plants due to a shorter growing period before flowering is triggered by day length. For sturdier growth, follow recommended spacing on the seed packet. For grain sorghum, this is often 4-8 inches apart in rows 24-36 inches apart.

Providing Adequate Support

Tall sorghum, especially in windy areas, may need support to prevent lodging. Here’s two effective methods:

Hilling: Mound soil around the base of the plants when they are about knee-high. This encourages additional root development for better anchorage.
Group Staking: For a small patch, place sturdy stakes at the corners of the planting and use twine to create a supportive corral around the entire group of plants.

The Lifecycle of Sorghum Growth

Understanding the growth stages helps you know what to expect.

Germination & Seedling Stage (0-3 weeks): Slow initial growth. Plants establish a deep root system.
Vegetative Stage (3-10 weeks): This is the period of rapid height gain. The stalk elongates, and leaves develop. Most of the maximum height achieved happens here.
Reproductive Stage (Week 10+): Growth in height slows and then stops as the plant focuses on flowering and developing the grain or seed head.
Maturity: The plant reaches its full height and the seeds harden. The leaves and stalk may begin to dry.

Common Problems Related to Height

Extreme height can sometimes lead to issues. Here’s what to watch for.

Lodging: This is when tall stalks fall over, usually due to wind, heavy rain, or weak stalks. It can make harvest difficult and promote disease. Choosing shorter varieties or providing support are the best preventions.
Shading: Very tall sorghum can cast significant shade on other plants in your garden. Plan your garden layout accordingly, placing it on the north side of other crops if you’re in the Northern Hemisphere.
Harvest Challenges: Harvesting seed heads from a 12-foot plant requires a ladder or a method of bending the stalk down. It’s something to consider before planting the tallest varieties.

FAQ About Sorghum Growth

How fast does sorghum grow?
Once established, sorghum can grow very rapidly during its vegetative stage, sometimes several inches per week under ideal warm, moist conditions.

What is the average height of sweet sorghum?
Most sweet sorghum varieties used for syrup production average between 8 to 12 feet tall. Some heirlooms can get even taller.

Can I control how tall my sorghum gets?
You can influence it by choosing the variety, managing soil fertility (avoiding excess nitrogen), and adjusting water. But you cannot drastically alter a variety’s genetic potential.

Does sorghum have deep roots?
Yes, sorghum is famous for its extensive and deep root system, which is key to its drought tolerance. This root system can extend down 5 feet or more, which also helps support its height.

What’s the difference between sorghum and corn height?
While both can get tall, field corn typically maxes out around 6-10 feet, similar to many sorghum varieties. However, the tallest sorghum varieties can significantly outgrow the tallest corn.

In the end, the question of ‘how tall does sorghum grow’ opens the door to understanding this adaptable crop. By selecting your variety with intention and providing good basic care, you can predict and manage its growth to fit your garden perfectly. Whether you prefer a manageable 4-foot stand of grain or a forest of 12-foot syrup stalks, there’s a sorghum variety ready to reach for the sky in your plot.