Johnson Grass Plant Care
Sorghum propinquum (Kunth) Hitchc.
Updated · Sources · How we source care data
Sorghum propinquum is a species of wild Sorghum native to most of tropical Asia, from India to Southeast Asia, southern China, Malesia and Papuasia. A perennial, rhizomatous diploid with the same number of chromosomes (2n=20) as the annual, non-rhizomatous diploid Sorghum bicolor, it is being studied for its potential for sorghum crop improvement.
Every 3–7 days
Full sun
70–90°F
40–60%
At a glance
How do you care for Johnson Grass?
Water Johnson Grass every 3–7 days, letting the top layer of soil dry out between waterings, and give it full sun. It prefers temperatures of 70–90°F (21–32°C) and 40–60% humidity. Fertilize it every 4 months during the growing season.
Where Is the Johnson Grass Native To?
What Is the Johnson Grass?
Johnson Grass (Sorghum propinquum) belongs to the Poaceae family within the Sorghum genus. Johnson Grass is native to most of tropical Asia, from India to Southeast Asia, southern China, Malesia and Papuasia. Johnson Grass is also known as Sorghum Grass.
Johnson Grass displays a tall, upright grass growth habit, reaching up to 8 ft tall with a spread of approximately 0.5 ft. Johnson Grass produces tall, feathery flower spikes.
Leaf size: approximately 24 inches.
How Often Should You Water a Johnson Grass?
Sorghum propinquum requires watering every 3–7 days. Allow the top layer of soil to dry between waterings to prevent root rot. Reduce watering frequency during winter when growth slows.
Watering Frequency
Every 3–7 days
Let soil partially dry between waterings
What Light Does the Johnson Grass Need?
Johnson Grass thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Johnson Grass Prefer?
Sorghum propinquum grows best at temperatures of 70–90°F. Johnson Grass prefers humidity levels of 40–60%.
Temperature
70–90°F
Humidity
40–60%
What Soil Mix Works Best for a Johnson Grass?
Well-draining loamy soil with good fertility. Good drainage is essential for Johnson Grass to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Johnson Grass?
Feed Johnson Grass every 4 months during the growing season (spring and summer) with a balanced fertilizer diluted to the strength on the label.
Pause feeding in autumn and winter, when growth slows, and never fertilize dry soil — water first.
Fertilizing
Every 4 months
During the growing season
The PlantoScan app can remind you when to water and when to fertilize each plant.
How Do You Repot a Johnson Grass?
Repot every 1-2 years in early spring. Choose a pot one size larger than the current container, and ensure it has drainage holes to allow excess water to escape.
How Do You Propagate a Johnson Grass?
Johnson Grass can be propagated through seeds. Similar propagation techniques also apply to reed sorghum plant care, which shares the same genus.
Is the Johnson Grass Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Johnson Grass, so we can't confirm whether it is safe for cats and dogs. Keep pets from chewing it as a precaution.
This is a general caution, not veterinary or medical advice. If your pet ate a plant, contact your vet or animal poison control.
See all plants toxic to cats and plants toxic to dogs.
What Pests and Diseases Affect the Johnson Grass?
Johnson Grass is susceptible to aphids, grasshoppers, cutworms. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.
Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.
What USDA Hardiness Zone Does the Johnson Grass Need?
Johnson Grass grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. Johnson Grass is native to most of tropical Asia, from India to Southeast Asia, southern China, Malesia and Papuasia. In cooler regions, grow Johnson Grass as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13b
Keep exploring plants
Johnson Grass is one of many species covered in the complete plant care and identification guide, which groups plants by genus, attribute, and popularity.
It belongs to the Sorghum genus — compare its care with other Sorghum species on PlantoScan.
Sorghum is part of the Poaceae plant family — browse all Poaceae genera and species.
Johnson Grass thrives in bright light and direct sun — see other bright-light plants.
More Sorghum Species
Other Sorghum species in PlantoScan's care catalogue share similar watering, light, and soil preferences:
Sources
- Scientific name & taxonomy: Sorghum propinquum (Kunth) Hitchc., family Poaceae (first published in Lingnan Sci. J. 7: 249 (1931)) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Johnson Grass, so we can't confirm whether it is safe for cats and dogs. Checked against the ASPCA plant list; any other toxicity note on this page comes from PlantoScan's plant database.
- Hardiness zone: USDA Zone 13b, calculated from the plant's minimum temperature.
- Care values(watering, light, temperature, humidity, soil, fertilizing): PlantoScan's plant database, filtered by automatic plausibility checks — values that fail them are hidden. How we source and check plant data.
Spotted a mistake? Email info@upvision.media with the page link — we check and correct reported errors.
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