Giganteus

Giganteus

SKU: FL3275
Inconspicuous Giganteus sunflower seeds produce absolutely huge plants in one short season. This is the giant among sunflowers, with towering stems up to 3.6m (12') tall, as thick as a man's leg. Read More

Exposure Full-sun

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West Coast Seeds ships anywhere in North America. However, we are not able to ship garlic, potatoes, asparagus crowns, bulbs, onion sets, Mason bee cocoons, or nematodes outside of Canada. We regret, we cannot accept returns or damages for orders outside of Canada. The minimum shipping charge to the US is $6.99.

More details about Giganteus

Helianthus annuus. Inconspicuous Giganteus sunflower seeds produce absolutely huge plants in one short season. This is the giant among sunflowers, with towering stems up to 3.6m (12') tall, as thick as a man's leg. At the top grows a monumental flower head up to 45cm (18") across, heavy with edible seeds. The seed heads tend to nod forward at maturity, facing down. Be sure to get the seeds planted early so the seed heads can mature before the wet weather arrives in September. It's a good idea to direct sow (as opposed to transplanting) these enormous plants so their root growth is not interrupted. They need a solid anchor in order to keep them standing upright.

Annual

Quick Facts:

    • Giant among sunflowers
    • Grows to 3.6m (12') tall
    • Edible seeds
    • Flowers to 45cm (18") across
    • Start early

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Giganteus

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All About Giganteus

Latin

Latin
Helianthus annuus
Family: Asteraceae

Difficulty

Difficulty
Easy

Season & Zone

Season & Zone
Exposure: Full sun

Timing

Timing
Direct sow repeatedly after the last frost date. Starting indoors is possible, but does not gain much time. If sunflowers are allowed to get root-bound, they will lack stability at transplant time, and will require staking. Optimal soil temperature for germination: 21-30°C (70-85°F). Seeds should sprout in 10-14 days.

Starting

Starting
Sow seeds 5mm-1cm  (¼-½”) deep. Space dwarf varieties 15cm (6″) apart, but give the giants lots of room at 1m (3′) between plants.

Growing

Growing
To grow really big plants with really big flowers, enrich the soil with organic matter and incorporate 2 cups of balanced organic fertilizer per 3m (10′) of row, and irrigate regularly. When the plants are 30cm (12) tall, dissolve 5ml (1 tsp) of borax (for boron) in 350 ml (12 fl oz) of water and spread the solution over 5m (15′) of row. Be careful not to over-apply this solution. This application of boron will produce bigger seeds and flower heads. Do not apply boron to other garden plants. When the back of the flower head turns yellow, it is ready to be cut from the plant.

Companion Planting

Companion Planting
Sunflowers planted near rows of corn are said to increase yields. Sunflowers can be used to draw heavy metals, toxins, and even radiation from soil, but should be burned at the end of the season if grown for this purpose. Plant sunflowers amid squash plantings to improve pollination and overall production.

More on Companion Planting.

How to Grow Sunflowers

Step 1: Timing

Direct sow repeatedly after the last frost date. Starting indoors is possible, but does not gain much time. If sunflowers are allowed to get root-bound, they will lack stability at transplant time, and will require staking. Optimal soil temperature for germination: 21-30°C (70-85°F). Seeds should sprout in 10-14 days.

Step 2: Starting

Sow seeds 5mm-1cm  (¼-½”) deep. Space dwarf varieties 15cm (6″) apart, but give the giants lots of room at 1m (3′) between plants.

Step 3: Growing

To grow really big plants with really big flowers, enrich the soil with organic matter and incorporate 2 cups of balanced organic fertilizer per 3m (10′) of row, and irrigate regularly. When the plants are 30cm (12) tall, dissolve 5ml (1 tsp) of borax (for boron) in 350 ml (12 fl oz) of water and spread the solution over 5m (15′) of row. Be careful not to over-apply this solution. This application of boron will produce bigger seeds and flower heads. Do not apply boron to other garden plants. When the back of the flower head turns yellow, it is ready to be cut from the plant.

Tip!

Companion Planting: Sunflowers planted near rows of corn are said to increase yields. Sunflowers can be used to draw heavy metals, toxins, and even radiation from soil, but should be burned at the end of the season if grown for this purpose. Plant sunflowers amid squash plantings to improve pollination and overall production.

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