Sunflower

Basic Information

Seed Number

67

Seed Name

Sunflower

Variety

Grey striped mammoth

Category

Flower

Plant Family

Asteraceae

Plant Type

Giant confectionery sunflower (Helianthus annuus)

Planting Method

Direct Sow

Seed Status

In Seed Bank

Created

2026-08-14 00:50:34

Updated

2026-08-19 15:35:29

Planting Information

Start Planting Date

May 6

Last Recommended Planting Date

Jun 20

Plantable Months

May, June

Indoor Start

Not recorded

Direct Sow

May 6 – Jun 20

Transplant

Not Recommended

Indoor Start Weeks Before Frost

Not Recommended

Transplant Weeks After Frost

Not Recommended

Germination Days

7–10 days

Harvest/Maturity

Not recorded

Succession Planting

Not recorded

Growing Conditions

Ideal Soil Temperature

60°F+

Planting Depth

1 in

Plant Spacing

24 in

Row Spacing

30-36 in

Thin-To Spacing

24 in

Sun Requirements

Full sun; 6-8+ hours/day

Water Needs

About 1 in/week; water deeply during establishment, flowering and seed fill

Soil Preference

Fertile, well-drained soil; approximately pH 6.0-6.8

Minimum Container Size

giants need ground/large pots

Plant Height

Up to 12 ft

Perennial/Biennial Status

Annual

Container Friendly

No

Trellis/Support Needed

No

Frost Tolerant

No

Heat Tolerant

Yes

Drought Tolerant

Yes

Pollinator Friendly

Yes

Medicinal

No

Garden Uses

Companion Planting

Storage

Seed Source/Brand

MSU Extension; Detroit frost dates; Almanac Detroit

Packet Year

Not recorded

Quantity Notes

Not recorded

Purchase Date

Not recorded

Expiration Year

Not recorded

Storage Box

Not recorded

Container

Not recorded

Envelope

Not recorded

Row

Not recorded

Slot

Not recorded

Storage Notes

Not recorded

Notes

Original Planting Method: Direct sow
Outdoor / Direct Sow / Transplant Window: May 10 – Jul 10
Days to Harvest / Bloom: 60–100 days to bloom
Container Friendly: Dwarf yes; giants need ground/large pots
Medicinal / Herbal Use: Seeds useful; pollinator support
Succession / Reusable Notes: Succession sow for blooms. Tall types need wind protection.
Zone 6B Notes: Direct sow after frost.
Companion Plants: Cucumbers, squash, pumpkins, melons, corn, pollinator flowers, clover
Avoid Planting Near / Watch Outs: Potatoes; may shade small crops
Sources: MSU Extension: https://www.canr.msu.edu/resources/garden_planning_calendar | Detroit frost dates: https://www.ufseeds.com/vegetable-planting-calendar-detroit-michigan.html | Almanac Detroit: https://www.almanac.com/gardening/planting-calendar/MI/Detroit

[[RESEARCH ENRICHMENT START]]
Zone 6B: Plant promptly after the May 5 last frost because this giant seed-producing sunflower needs a long season to fully ripen its large heads before fall frost.
Germination: Direct sow approximately 1 inch deep after soil warms. Sunflower seed typically germinates in 7-10 days.
Harvest: For edible seed, allow the back of the flower head to yellow and then brown while the seeds become plump and firm. Protect ripening heads from birds if necessary.
Seed Saving: Mammoth Grey Stripe is an open-pollinated sunflower type but will cross readily with other Helianthus annuus varieties. Isolate if maintaining true seed.
Special Care: Very tall, single-stemmed plants with extremely large seed heads may become top-heavy; a wind-protected planting site is helpful.
Research Source: Ferry-Morse / Home Depot — https://www.homedepot.com/p/Ferry-Morse-Sunflower-Mammoth-Grey-Stripe-Seed-Bonus-Pack-6544/207097709 — Mammoth Grey Stripe identity, single-stem habit, up to 12-foot height and edible seed use
Research Source: University of Minnesota Extension — https://extension.umn.edu/gardening-minnesota/sunflowers — 7-10 day germination, direct sowing after frost, 1-inch depth and 24-inch spacing for giant sunflowers
[[RESEARCH ENRICHMENT END]]