Johnsongrass Plant Care
Sorghum halepense Pers.
Updated · Sources · How we source care data
Johnson grass or Johnsongrass, Sorghum halepense, is a plant in the grass family, Poaceae, native to Asia and northern Africa. The plant has been introduced to all continents except Antarctica, and most larger islands and archipelagos.
Every 3–7 days
Full sun
70–90°F
40–60%
At a glance
How do you care for Johnsongrass?
Water Johnsongrass 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.
What Is the Johnsongrass?
Johnsongrass (Sorghum halepense) belongs to the Poaceae family within the Sorghum genus. Johnsongrass is native to Asia and northern Africa. Johnsongrass is also known as Sorghum grass, Cane grass, Green grass.
Johnsongrass displays a tall, upright grass growth habit, reaching up to 8 ft tall with a spread of approximately 0.5 ft. Johnsongrass produces tall, feathery flower spikes.
Leaf size: approximately 24 inches.
How Often Should You Water a Johnsongrass?
Sorghum halepense 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 Johnsongrass Need?
Johnsongrass thrives in full sun.
Light Requirement
Full sun
What Temperature and Humidity Does the Johnsongrass Prefer?
Sorghum halepense grows best at temperatures of 70–90°F. Johnsongrass prefers humidity levels of 40–60%.
Temperature
70–90°F
Humidity
40–60%
What Soil Mix Works Best for a Johnsongrass?
Well-draining loamy soil with good fertility. Good drainage is essential for Johnsongrass to prevent waterlogging, which leads to root rot and fungal issues.
How Often Should You Fertilize a Johnsongrass?
Feed Johnsongrass 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 Johnsongrass?
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 Johnsongrass?
Johnsongrass can be propagated through seeds. Similar propagation techniques also apply to reed sorghum plant care, which shares the same genus.
Is the Johnsongrass Toxic to Pets and Children?
Pet safety not verified
The ASPCA does not list Johnsongrass, 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 Johnsongrass?
Johnsongrass 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 Johnsongrass Need?
Johnsongrass grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. Johnsongrass is native to Asia and northern Africa. In cooler regions, grow Johnsongrass as a houseplant or bring it indoors before the first frost.
Hardiness Zone
Zone 13b
Keep exploring plants
Johnsongrass 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.
Johnsongrass 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 halepense Pers., family Poaceae (first published in Syn. Pl. [Persoon] 1: 101. 1805 [1 Apr-15 Jun 1805]) — World Flora Online record, IPNI name record.
- Pet toxicity: Pet safety not verified: the ASPCA does not list Johnsongrass, 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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