Mammoth Sunflower Seeds — 2-second swaying plant cover

Mammoth Sunflower Seeds

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About the Variety

Mammoth Sunflowers are known for their towering stems and oversized golden-yellow flower heads, creating a stunning focal point in large, sunny gardens. Growing up to 12 feet tall under favorable conditions, these giant sunflowers thrive in spacious outdoor areas with plenty of sunlight and room to grow. Ideal for garden backdrops, large flower beds, and open landscapes.

Towering Growth — Can reach up to 12 feet tall
Giant Golden Blooms — Oversized, eye-catching flower heads
Ideal for Spacious Gardens — Perfect for large flower beds and garden backdrops

Key Features

Giant Flower Heads
Up to 12 ft Tall
Ideal for Large Gardens
Attracts Pollinators
Full Sun

Plant Details

Botanical Name	Helianthus annuus
Life Cycle	Annual
Seed Type	Open-pollinated
Light Requirement	Full sun
Bloom Season	Summer through fall
Growth Habit	Tall, upright
Plant Height	Up to 12 ft (3.7 m), depending on growing conditions.
Plant Type	Giant, single flower head
Color	Yellow with a dark center

Planting Information

Planting Season	Spring after the last frost
Sowing Method	Direct sow after frost
Planting Depth	Reference: 1/2 inch; verify against the supplied seed lot
Water Needs	Average; water during establishment
Plant Spacing	18–24 inches (45–60 cm) apart after thinning.
Hardiness Zones	Annual; suitable for growing during the frost-free season in most USDA zones.
Germination	Typically 7–14 days in warm, moist soil.
Seed Prep	No special pre-treatment required. Sow directly without soaking or cold stratification.

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FAQs

How do you ship?

Seeds ship after a handling period of 3-5 business days, with most orders arriving within 10-15 business days from there.
Once your order leaves our warehouse, you'll receive a shipping confirmation email with tracking — so you know exactly where things stand.

Are your products GMO?

All of our seedsare non-GMO. We've made that commitment as our Safe Seed Pledge.

Are your seeds treated?

Most of our seeds are untreated. Some varieties are coated with a fungicidal treatment to support germination and early establishment, particularly in challenging growing conditions. If a variety has been treated, it will be clearly noted on the product page and packaging.

How Should I Store Unused Seeds?

Our recommendation is to buy for the season you're planting. But if you have seed left over, proper storage keeps it viable longer than most people expect.

To store unused seeds:

1. Seal them in an airtight container or plastic bag to protect against moisture and insects
2. Keep them somewhere cool, dark, and dry — away from sunlight and humidity
3. Skip the refrigerator; fluctuating moisture is harder on seed than temperature

Stored well, most seeds hold through the following growing season with excellent results. Our seeds typically lose less than 5% of their viability per year under ideal conditions.

Not sure if older seed is still good? A quick germination test will tell you:

Moisten a paper towel, place 10 seeds on one half, fold it over, and seal it in a plastic bag or airtight container. Keep it in a warm location appropriate for the variety, and check periodically over the seed's normal germination period. Count how many sprout — 8 of 10 means roughly 80% viability. If the rate is low, you can often compensate by sowing more thickly. Just keep in mind this measures viability under ideal conditions, so actual garden performance can vary with soil, moisture, and weather.