Towering 9-12 FEET (3-4 M), these Mammoth Grey Stripe Sunflowers are a truly massive and gorgeous, showy addition to your garden!  Easy to grow, easy to harvest, and with a lovely nutty flavor, they’re a winner for your garden and snacking needs.  Flower diameters top out at around 12 inches (30 cm).  Seeds are much larger than many homegrown varieties, rivaling and often larger than those bought at the store for eating.

Key Growing Facts:  Full Sun - Warm weather annual (grows one season) - Tolerant of many soils and climates - Start outdoors (direct sow) or indoors for transplant - Harvest times vary based on climate, but generally 4 months

Germination:  If possible, start your seeds outdoors by directly sowing in the garden.  This should work fine for most temperate, subtropical, and tropical climates.  Soil temperatures should be warm and the soil should be moist but not soggy.  Look for soil temps of approximately 60-70 F / 15-20 C or above.  Germination is typically easy, but these simple guidelines absolutely MUST be followed to avoid rot and failure.

If your growing season is very short or the spring is just too cool to rely upon, starting indoors is an option – just be ready to transplant quickly to outdoors, as the seedlings grow so quickly.

Fertilizing:  Even “giant” sunflowers like these Mammoths are generally light feeders and do not usually require fertilizer for average soils.  If you wish, or if your soil is very poor, fertilize occasionally with your choice of natural or synthetic fertilizer, balanced for your soil conditions.  Compost or composted manure is an excellent choice if you have access to it.

Harvest:  Sunflowers ripen best in autumn/fall conditions that are generally warm and dry.  Cool or even cold nights are fine, and light frosts and heavy dew won’t hurt them, but do plant early enough to ensure ripening finishes prior to freezes, which kill and halt seed ripening.

Like other familiar flowers, you will notice the petals drying and eventually falling off as the seeds mature and then dry.  Test seeds every few days at this point for dryness – best done with your own mouth!  If the weather is turning consistently rainy, consider cutting off the flower heads and rubbing off the seeds and then drying them further in a covered location with a fan.

Being a native of Mexico and North America, many native bird species will likely visit at this vulnerable time to raid your flowers, regardless of your state/province or climate.  If you’re fine with this, let them have it!  If not, consider covering or “bagging” the flower heads with a breathable bag.  Just don’t cinch too tightly or they will remain moist and rot.

Wire mesh (“hardware cloth”) or similar over a bucket or garbage can is a great and efficient at-home method for rubbing the seeds off the heads.

I have personally sown and cultivated every parent plant from seed, and then harvested and properly dried every seed.  They were fed only with natural compost and not sprayed with any pesticide or herbicide.  Fortunately, sunflowers do not generally suffer too many diseases or pests, especially in our fairly short temperate growing season here in southeast Michigan, USA (USDA Zone 6a).