Sunflower Russian Mammoth
Helianthus annuus 'Russian Mammoth'
The giant of the sunflower world, this heirloom variety produces enormous flower heads up to 12 inches across on towering 10-foot stalks. Not only spectacular for garden displays and cut flowers, but also produces abundant large seeds perfect for snacking or feeding birds. A true showstopper that creates instant impact in any garden space.
Harvest
110-120d
Days to harvest
Sun
Full sun
Zones
2–11
USDA hardiness
Height
1-10 feet
Planting Timeline
Showing dates for Sunflower Russian Mammoth in USDA Zone 7
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Sunflower Russian Mammoth · Zones 2–11
Growing Details
Zone-by-Zone Planting Calendar
| Zone | Indoor Start | Transplant | Direct Sow | Harvest |
|---|---|---|---|---|
| Zone 3 | April – May | June – July | June – August | — |
| Zone 4 | March – April | June – June | June – July | — |
| Zone 5 | March – April | May – June | May – July | — |
| Zone 6 | March – April | May – June | May – July | — |
| Zone 7 | February – March | April – May | April – June | — |
| Zone 8 | February – March | April – May | April – June | — |
| Zone 9 | January – February | March – April | March – May | — |
| Zone 10 | January – January | February – March | February – April | — |
Complete Growing Guide
Light: Full sun (6 or more hours of direct sunlight a day). Soil: Clay, Loam (Silt), Sand. Drainage: Good Drainage. Height: 1 ft. 6 in. - 10 ft. 0 in.. Spread: 1 ft. 6 in. - 3 ft. 0 in.. Spacing: 12 inches-3 feet. Growth rate: Rapid. Maintenance: Low. Propagation: Seed. Regions: Coastal, Mountains, Piedmont.
Harvesting
Seeds are ovoid and somewhat flattened
Color: Black, Brown/Copper. Type: Achene. Length: < 1 inch. Width: < 1 inch.
Garden value: Edible
Harvest time: Fall
Bloom time: Fall, Summer
Edibility: Seeds are used for cooking oil, livestock feed, and as a snack food or garnish. Petals are edible and young flower buds can be steamed like artichokes.
Storage & Preservation
Fresh-cut Russian Mammoth flower heads store best in a cool, dry location with good air circulation. Hang heads upside down in a garage or shed for 2-3 weeks to complete drying, covering with cheesecloth to protect from birds while allowing airflow.
Once fully dried, remove seeds and store in airtight containers in a cool, dark place. Properly dried seeds maintain viability for 2-3 years and eating quality for 6-12 months. For long-term storage, freeze seeds for 48 hours to eliminate any insect eggs, then store in sealed glass jars with silica gel packets.
Roast fresh seeds immediately after harvest by soaking in salt water for 8-10 hours, then baking at 300°F for 15-20 minutes until golden. Roasted seeds keep in airtight containers for 1 month at room temperature or 6 months frozen. Save the largest, most perfect seeds for next year's planting, ensuring genetic continuity of this magnificent heirloom variety.
History & Origin
Origin: Western United States
Advantages
- +Disease resistance: Deer, Drought, Dry Soil, Poor Soil
- +Attracts: Butterflies, Pollinators, Songbirds, Specialized Bees
- +Edible: Seeds are used for cooking oil, livestock feed, and as a snack food or garnish. Petals are edible and young flower buds can be steamed like artichokes.
- +Fast-growing
- +Low maintenance
Companion Plants
Plant Together
Cucumber
Benefits from sunflower's tall shade and wind protection while utilizing different soil nutrients
Corn
Similar growing requirements and complementary root systems, both benefit from deep watering
Squash
Enjoys partial shade from tall sunflowers and helps suppress weeds around sunflower base
Bean
Fixes nitrogen in soil which benefits heavy-feeding sunflowers, appreciates wind protection
Nasturtium
Acts as trap crop for aphids and cucumber beetles that may target sunflowers
Marigold
Repels nematodes and aphids while attracting beneficial insects for sunflower pollination
Lettuce
Benefits from afternoon shade provided by tall sunflowers, especially in hot climates
Radish
Quick-growing crop that breaks up soil around sunflower roots and deters root maggots
Keep Apart
Black Walnut
Produces juglone which is toxic to sunflowers and inhibits their growth
Pole Bean
May climb sunflower stalks and cause them to bend or break under additional weight
Fennel
Allelopathic properties inhibit growth of sunflowers and most other garden plants
Potato
Competes heavily for nutrients and water, both are heavy feeders with similar root zones
Nutrition Facts
Per 100g serving. % Daily Value based on 2,000 calorie diet. Source: USDA FoodData Central (FDC #169270)
Pests & Disease Resistance
Resistance
Generally disease resistant, may develop downy mildew in humid conditions
Common Pests
Birds, squirrels, sunflower beetles, aphids
Diseases
Downy mildew, rust, bacterial wilt, sclerotinia head rot