Mammoth Sunflower Growing Guide: Tips for Huge Flowers and Healthy Plants

There are sunflowers, and then there are SUNFLOWERS! Mammoth sunflowers are the king of sunflowers and can grow 12 feet tall. These are the sunflowers to grow if you are looking to impress your kids, the neighbors, or even the squirrels.

Mammoth sunflower seeds are simple to sow directly into the ground outdoors. 

Plant seeds 1” deep. Sunflower seeds don’t need light to germinate; this depth will keep them away from birds.

Put netting over the seeds until they are sprouted to keep birds and other animals from eating them.

Plant 2 to 3 seeds per spot in case one gets eaten. Once they have sprouted, thin out to keep the strongest plant.

• Plant seeds 1 inch deep after all danger of frost has passed. 

• Keep soil moist but not soggy. 

• Sunflower seeds germinate in 7 to 14 days.

• Mature sunflower plants prefer drier conditions.

You can also start mammoth sunflower seeds indoors to get an earlier start on the season and to protect seeds and seedlings.

Once the sunflower seeds sprout, they must be planted outside in 2 to 3 weeks. Sunflowers have a long taproot that can quickly reach the bottom of the pot and then become stunted. Using biodegradable pots will make transplanting easier on the roots.

Sunflowers are one of the easiest flowers to grow. And the same holds true for Mammoth Sunflowers. However, because of their size, there are a few tips you’ll want to know to ensure an impressive harvest of sunflower seeds.

Mammoth sunflowers love the summer sunshine and need a location with full sun. Six hours of direct sunlight is the minimum. But for the biggest growth possible, try for 8 hours. Another thing to consider is that these giant sunflowers can easily shade out other plants. So take this into consideration when deciding where to plant sunflowers in your garden. 

Mammoth sunflowers don’t really need great soil, but they will grow better with plenty of nutrients. Start with nutrient-rich soil that is warm. The ideal soil temperature for sunflower seed germination is between 70º and 75ºF. A pH of 6.0 to 7.5 is optimal.

Keep weeds out so they aren’t competing with your flowers for water and nutrients. Sunflowers don’t usually need fertilizer. But if you want to give mammoth sunflowers even more of an edge, you can add extra compost and a slow-release fertilizer. Sunflowers have long taproots, so water deeply and not too often. Let the soil dry out between watering, which will encourage the taproot's deep growth. 

Mammoth sunflowers can get heavy and knocked down in a windstorm. But they do grow a very strong stalk that can support the big flower head. It’s just a matter of the wind hitting the sunflower plant at the right angle to knock them over and expose the roots. If this happens, sometimes you can prop the stalk up and get the roots back in the earth so the sunflower can continue growing. However, sometimes the upheaval has damaged the roots too much. You can use staking and support methods used in flower farms, such as row strings and fencing. Put in any supports before the roots get set since putting in something later could break the roots.

Mammoth Sunflowers are an heirloom variety that originated in North America. They are prized for their enormous head that can grow up to 14 inches across. The stalks of these sunflowers can grow up to 12 feet tall and are as wide as a small sapling. The thick stems support the weight of the heavy head full of delicious sunflower seeds. If you want an amazing sunflower that towers over the garden and has a large harvest of seeds to eat, plant Mammoth Sunflower Seeds.

Harvesting sunflower seeds is one of the most rewarding parts of growing Mammoth sunflowers. The large flower heads can produce hundreds of edible seeds for roasting, snacking, bird feeding, or saving for next year's garden.