Ashy Sunflower (Helianthus mollis)

Photo: Eric HuntCC BY-SA 4.0via Wikimedia Commonsresized / cropped

Ashy Sunflower Plant Care

Helianthus mollis Lam.

Updated · Sources · How we source care data

Helianthus mollis is a species of sunflower known by the common names ashy sunflower, hairy sunflower or downy sunflower. It is widespread across much of the United States and Canada, primarily the Great Lakes region from Ontario south to Texas and Alabama. Additional populations are found in the states of the Atlantic Coast from Maine to Georgia, but these appear to be introduced.

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Water

Every 7–10 days

Light

Full sun

Temp

65–85°F

Humidity

40–60%

At a glance

How do you care for Ashy Sunflower?

Plant Ashy Sunflower in full sun (USDA zones 13b) and water a young tree every 7–10 days until it is established. It tolerates temperatures of 65–85°F (18–29°C). Fertilize it every 6 months during the growing season.

Where Is the Ashy Sunflower Native To?

Native range1 country

What Is the Ashy Sunflower?

Ashy Sunflower (Helianthus mollis) belongs to the Asteraceae family within the Helianthus genus. Ashy Sunflower is native to the states of the Atlantic Coast from Maine to Georgia. Ashy Sunflower is also known as Soft Sunflower, Helianthus canescens, Helianthus mollis.

Ashy Sunflower displays a tall, upright stems with large flower heads growth habit, reaching up to 6 ft tall with a spread of approximately 2 ft. Ashy Sunflower produces large, yellow, daisy-like flower heads.

Leaf size: approximately 6 inches.

How Often Should You Water a Ashy Sunflower?

Water a young or newly planted Ashy Sunflower every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Watering Frequency

Every 7–10 days

Until established; then in dry spells

What Light Does the Ashy Sunflower Need?

Ashy Sunflower thrives in full sun.

Light Requirement

Full sun

What Temperature and Humidity Does the Ashy Sunflower Prefer?

Helianthus mollis tolerates temperatures of 65–85°F. Ashy Sunflower prefers humidity levels of 40–60%.

Temperature

65–85°F

Humidity

40–60%

What Soil Mix Works Best for a Ashy Sunflower?

Well-draining loamy soil with added compost for nutrients. Good drainage is essential for Ashy Sunflower to prevent waterlogging, which leads to root rot and fungal issues.

How Often Should You Fertilize a Ashy Sunflower?

Feed Ashy Sunflower every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

Fertilizing

Every 6 months

During the growing season

The PlantoScan app can remind you when to water and when to fertilize each plant.

Where Should You Plant a Ashy Sunflower?

Choose a spot with full sun and well-draining loamy soil with added compost for nutrients. Avoid low spots where water collects after rain.

Ashy Sunflower is suited to USDA Zone 13b.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

How Far Apart Should You Plant a Ashy Sunflower?

Ashy Sunflower can spread to about 2 ft (0.6 m) and reach about 6 ft (2 m) tall. Space plants about 2 ft (0.6 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

How Do You Prune a Ashy Sunflower?

Prune Ashy Sunflower while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

How Do You Care for a Ashy Sunflower in Winter?

Ashy Sunflower is frost-tender (hardy to USDA zone 13). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

How Do You Propagate a Ashy Sunflower?

Ashy Sunflower can be propagated through seeds. Similar propagation techniques also apply to proceedings of the biological society of washington plant care, which shares the same genus.

Is the Ashy Sunflower Toxic to Pets and Children?

Pet safety not verified

The ASPCA does not list Ashy Sunflower, 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 Ashy Sunflower?

Ashy Sunflower is susceptible to aphids, caterpillars, powdery mildew. 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 Ashy Sunflower Need?

Ashy Sunflower grows outdoors in USDA Zone 13b. It survives winters down to planting zone 13b. Ashy Sunflower is native to the states of the Atlantic Coast from Maine to Georgia. In cooler regions, grow Ashy Sunflower as a houseplant or bring it indoors before the first frost.

Hardiness Zone

Zone 13b

Keep exploring plants

Ashy Sunflower 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 Helianthus genus — compare its care with other Helianthus species on PlantoScan.

Helianthus is part of the Asteraceae plant family — browse all Asteraceae genera and species.

Ashy Sunflower thrives in bright light and direct sun — see other bright-light plants.

More Helianthus Species

Other Helianthus species in PlantoScan's care catalogue share similar watering, light, and soil preferences:

Sources

  • Scientific name & taxonomy: Helianthus mollis Lam., family Asteraceae (first published in Encycl. 3: 85 (1789)) — World Flora Online record, IPNI name record.
  • Pet toxicity: Pet safety not verified: the ASPCA does not list Ashy Sunflower, 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.
  • Photo: Eric Hunt, CC BY-SA 4.0, Wikimedia Commons — original.
  • 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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