Russian Mammoth sunflowers are a favorite in the garden! Russian Mammoth sunflowers mature in 80 days with 12′ stalks and giant heads. Thin-shelled, striped seeds are plump, meaty, and very plentiful. Easy to grow and attracts butterflies!
Planting by Zones
- Sunflowers can be grown year round in Zones 9 and 10 but are the happiest in the warm season.
- Direct sow seeds in the spring once soils have warmed.
Planting Russian Mammoth Sunflower
- In Zones 9 and 10, you can direct seed or transplant out your sunflower plants. We recommend you direct seed into freshly irrigated soils.
- To direct sow, plant seeds in debris-free, well-worked soil that has been deeply watered. Cover with 1” of finely sifted soil.
- If you are planting seeds in starter pots, plant seeds into thoroughly moist high-quality seed starting soil. Place seeds on top of the soil and cover with 1” of finely sifted soil.
- Once your sunflowers have germinated and the first set of true leaves show, fertilize with an organic liquid fertilizer. When the plants are 3-4” tall you can plant them out into the garden. Space at least 12” apart.
Growing Russian Mammoth Sunflower
- Sunflower plants should be planted into well-worked soils for the best blooms. In Zones 9 and 10, adding tons of compost will help create a healthy soil structure and keep soil moistures in, which is key.
- Mulching heavily around your plants will also help with weed suppression and moisture retention.
Harvesting Russian Mammoth Sunflower Blooms
- Harvest sunflower blooms when the flowers are almost fully open.
- Harvest early in the morning and place blooms directly in a vase of room temperature water.
Growing Sunflower in Containers
- You can grow sunflower in a container but make sure your container is at least 10” deep. Keep in mind containers will dry out faster because they have more surface area and less soil to hold onto moisture. Mulch heavily on the top layer of soil in the pot to keep the soil from drying out or heating up too much.
Southern California Pro-tips
- Mulch heavily around your sunflower plants to ensure the soil does not dry out or overheat.
- Do not overhead water as this promotes foliar diseases.
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