Mammoth Sunflower

Asteraceae

Living trellis and pollinator magnet. 6-12 ft tall, 8-14 inch flower heads. Supports pole beans and cucumbers as Three Sisters variant — plant sunflowers 2-3 weeks before beans, allow 4-5 inch stem diameter before training climbers. Major late-season nectar source. ALLELOPATHIC — roots release growth-inhibiting compounds. Avoid near potatoes.

At a Glance

Days to Maturity

65–80 days

Sun

6+ hours

Container

Not Ideal

Height

6–12 ft

Zone Planting Guide

Your USDA Zone:

Growing Guide

Germination

Germination Time 10–15 days

Optimal Temp 70°F

Seed Depth 1"

Watering

Needs Moderate

Resilience

Heat: High Cold: Low Drought: Medium

Nutrition

Feeding Intensity Moderate feeder

Harvest

Flowers/foliage at desired stage

Sources

university Multiple extension sources university_extension NC State Extension Gardener Plant Toolbox

More Flowers

Mammoth Sunflower Planting Dates by Zone

Planting dates for Mammoth Sunflower vary by USDA hardiness zone. Select your zone below for frost dates, start-indoors timing, and a full monthly planting calendar.

Zone 5A Zone 5B Zone 6A Zone 6B Zone 7A Zone 7B Zone 8A Zone 8B Zone 9A Zone 9B

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