Mammoth Grey Stripe Sunflower Seeds


Mammoth Grey Stripe is a classic giant variety that produces large edible seeds and grows so tall that it is sure to make a statement in any garden! Mammoth Grey Stripe is a single-stemmed sunflower that can reach up to 8-12 feet or more, so it may need support if you push it to its limits!

The sturdy plants produce huge blooms that are 8-12 inches across, with the classic recognizable golden-yellow petals surrounding a dark chocolate central disk. Fun to watch growing so fast, Mammoth Grey Stripe is an excellent choice for a children’s garden, or they can also be used as a privacy screen.

In Native American inspired agriculture, it is common to add sunflowers as a ‘’fourth sister’’ to your ‘’three sisters’’ arrangement of bean, corn and winter squash to provide a bit more shade. The bees, birds and butterflies love to nourish themselves with them, and so will you once you’ve roasted and enjoyed your own home-grown sunflower seeds!


- Latin Name: Helianthus annuus
- Life Cycle: Annual
- Days to Maturity: 90-110
- Planting Depth: 1-2 cm deep
- Plant Spacing: 30 cm
- Growth Habit: 2-3 m tall


A true icon of the summer season, it’s difficult not to smile upon seeing a sunflower in full bloom. Sunflowers manage to make the summer season even sunnier and happier than it already is. The flowers are usually 10-15 cm wide and bloom from mid-summer into the early fall. Sunflowers typically grow tall, a metre or more, and reach maturity 80-120 days after germination. But with all of the different varieties available these days, dimensions, colours and growth habits can vary greatly based on type.

Sunflowers are fast growing annuals, completing their entire life cycle in a season. By the end of the year, the central disks produce seeds, attracting and feeding the local wildlife.

Start seeds outdoors after the danger of frost has passed and soil temperatures have reached 13 degrees. A few weeks before the last frost, use biodegradable peat or coco pots to start seeds indoors. Sunflowers don’t like their roots to be disturbed.

When preparing the planting site, keep in mind that sunflowers grow taproots that reach deep down into the earth. Dig a bed 60 cm deep and 90 cm across to provide plenty of space for roots to develop and create a sturdy base. Work in plenty of compost or a slow-release fertilizer while preparing the bed, as sunflowers will feed heavily through the growing season. 

The planting site, of course, should receive full sun. Sunflowers will require long warm days to get the energy needed for flower production. A site that provides some shelter from the wind could help keep the tall flowers standing upright. Plant against a wall or fence, or provide other support with stakes or trellises.

To start seeds, plant them 3-5 cm deep and about 15 cm apart in your well-prepared bed. If you have an abundance of seeds, plant them closer and thin to the strongest seedlings when they reach 15 cm tall. Water them in well and keep the soil moist. Netting can be placed over the bed to keep birds and other critters from sneaking off with your freshly planted seeds. Mulch can also be spread over the bed to help retain moisture and suppress weeds while sunflowers germinate and to get established. Water deeply and infrequently when plants are established.

Cut the main stalk right before the flower bud opens to encourage lots of side growth. Harvest flowers early in the morning to avoid wilting and handle with care. Add them to bouquets in containers tall enough to support their heavy heads and change water daily to extend their vase life.

What a joy it is to take in the sun and track its path alongside the cheerful faces of our sunflowers on long, hot summer days.


- Young sunflowers track the sun from sunrise to sunset every day, a process known as heliotropism. Once they reach maturity, they stop tracking the sun, and their blooms will be forever turned eastward.

- Sunflower seeds will remain viable for 1 year if stored in a cool, dark place, ideally between 4 and 10⁰C. After that, the germination rate may start to go down.


You know that a lush, fruitful garden needs good soil, frequent watering, and sunlight to grow, but it’s the seeds that really make the harvest.

Picked and bagged for 2023 the vast majority of our seeds have germination rates of over 85%. The seeds are all-natural, non-GMO, non-hybrid, untreated, and open-pollinated for seed saving.

We have put a lot of thoughts into the design and packaging of our seed packets. Our seeds are all carefully packed in food grade kraft paper/aluminium zipper lock bags, and then are shipped in eco-friendly padded mailers.

We heat-seal each of our seed packet for even more protection from moisture, odour and light, allowing you to store your seeds for up to 3x longer than paper or plastic. Plant them all, germinate some indoors, save some for next season - it’s up to you!

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Filter Reviews:
Virginia B.

I can't wait to see them bloom! An extra p...

I can't wait to see them bloom! An extra packet of seeds was sent as well and was greatly appreciated

Kelsey S.

I was immediately impressed with the packa...

I was immediately impressed with the packaging! So gorgeous. I can't wait to plant everything this spring.

Kelsey S.

I was immediately impressed with the packa...

I was immediately impressed with the packaging! So gorgeous. I can't wait to plant everything this spring.


J'ai hâte au printemps pour planter mes be...

J'ai hâte au printemps pour planter mes beaux légumes

Jess F.

The seeds arrived quickly and were package...

The seeds arrived quickly and were packaged really well. They will make for an awesome gift, thank you!