You can grow sunflowers in almost any size: from small dwarfs that grow to only 2 feet to giants reaching up to 12 feet in height. The larger varieties will need larger containers, at least 3-5 gallons, but are at risk of toppling over if you are up high where there is a lot of wind. We recommend one of the small or medium varieties for balcony gardens, as they will be easier to manage.
To eliminate the guesswork in selecting the right size containers for your plants, we’ve put together a list of commonly grown herbs, veggies, fruit and flowers along with the minimum pot sizes required by each. Get the Free Container Size Guide for Small Space Gardening .
Direct sow sunflower seeds from mid-April to late May, after the last spring frost date when soil temperatures have warmed. Smaller varieties will need a pot at least 15 cm (6″) in diameter. Plant seeds at least 15 cm (6″) apart, covering with 0.5 to 1 cm (1/4″-1/2″) of soil. Keep soil moist, and seeds should sprout in 10-14 days.
Water only when the top 1″ of soil is dry to the touch, as sunflowers are drought tolerant and do not grow well in waterlogged soil.
Because sunflowers grow so vigorously, they are heavy feeders that require nutrient-rich soil. When planting, you can work a granular slow-release fertilizer into the soil. Alternatively, fertilize occasionally (according to the directions given on your specific fertilizer) with an all purpose balanced liquid fertilizer.
Where Can I Grow It?
As most varieties get quite large, it is best to grow sunflowers outdoors. As the name implies, sunflowers are sun lovers that require at least 6-8 hours of sunlight, so it is best to give them the sunniest location possible.
Sunflowers are susceptible to toppling over in the wind, so a sheltered location against a wall, or staking them for support is best.
Sunflowers are ready for harvesting when the back of the flower has turned from green to yellow or brown. The flower head can then be cut at the base, and hung for further drying. When seeds are fully dry, they can be harvested for eating or planting.
Although the most common color is yellow, sunflowers range in color all the way from yellow, to orange, to red.
Grow sunflowers along with tomatoes, peppers, or cucumbers for beneficial effects. Sunflowers are helpful to have in gardens as they prevent aphids from infesting the rest of your plants. Industrious ants will herd aphids onto the sunflower stalks, reducing the number of aphids elsewhere in the garden. Sunflowers are also great for keeping thrips away from your pepper plants.