Growing Sunflower

helianthus annuus : Asteraceae / the daisy family

Jan F M A M J J A S O N Dec
        P P            

(Best months for growing Sunflower in USA - Zone 5a regions)

  • P = Sow seed
  • Sow in garden. Sow seed at a depth approximately three times the diameter of the seed. Best planted at soil temperatures between 50°F and 86°F. (Show °C/cm)
  • Space plants: 8 - 18 inches apart
  • Harvest in 10-11 weeks.
  • Compatible with (can grow beside): Cucumbers, Melons, Sweetcorn, Squash
  • Avoid growing close to: Potatoes

Your comments and tips

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21 Feb 23, Jordan (USA - Zone 5b climate)
Hi! We are looking to plant sunflowers from seeds in the North Shore of Chicago area, I believe we are zone 5b for zip code 60045. I have seen people reference "the guide" but am curious if someone could point me towards where I might find this magical panacea of information? Thank you! (Gardenate uses https://www.gardenate.com/zones/#zone-US)
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22 Feb 23, Anonymous (Australia - sub-tropical climate)
You work out your climate zone from the blue tab at the top of the page. Then go to the plant you want to grow - sun flowers.
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21 Aug 22, Jennifer Bozick (USA - Zone 6a climate)
When is a good date to start planting Sunflowers in Kansas 6a growing zone?
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04 Sep 22, (USA - Zone 6a climate)
In the Planting Guide it says APRIL MAY.
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13 Aug 22, Theresa C. Dougherty (USA - Zone 7b climate)
Can I plant sunflower seeds in mid August to get fall sunflowers .? I live in zone 7 b ,I grow them first in side and plant outside .
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23 Jun 22, Cristal Chacon (USA - Zone 8b climate)
I planted sunflower seeds today. Hoping to get blooms by mid August. Do you think this will happen? Or not enough time?
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14 Apr 22, Marjorie (USA - Zone 9b climate)
I’m planting mammoth sunflower in zone 9b (FL). I started the seeds in containers and moved them to the ground. For some flowers, I dug holes and filled with garden soil. For others, I planted in the ground, which is sandy. Those seem to be doing okay, too. They get sun from sunrise to sundown. Would you plant them in sandy soil?
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19 Apr 22, (USA - Zone 5a climate)
Sandy soils just require more watering and fertilising.
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05 Apr 22, Stella Vance (USA - Zone 7a climate)
When is the best time to plant sunflowers or any flowers from seed?
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10 Apr 22, Celeste Archer (Canada - Zone 7b Mild Temperate climate)
Most seeds have what is know as a "germination" temperature -- this ensures that seeds do not germinate in the middle of winter. Here are some basic germination temperatures in F ==> Snapdragon (Antirrhinum majus) 70 Wax Begonia (Begonia x semperflorens-cultorum) 70-75 , Annual Aster (Callistephus chinensis) 70 , Vinca (Cathranthus roseus) 70-75 , Cockscomb (Cleosia spp.) 70-75 , Bachelor's Button (Centaurea cyanus) 65-70 , Cosmos (Cosmos spp.) 70 , Lisianthus (Eustoma grandiflorum) 75 , Globe Amaranth (Gomphrena globosa) 70 , Sunflower* (Helianthus annuus) 70 , Strawflower (Helichrysum bracteatum) 70-75 . Furthermore the germination temperature needs to be sustained -- so for example if the temperature hit 70f for a couple of hours in the middle of the day and the reset of the time the temperature is 40f ==> germination will probably not occur. Sustained temperatures is how the seed KNOWS it is spring/summer -- when you start your seeds indoors, you are tricking the plant into thinking it is spring and the temps are good and it is a good time to germinate (the seedling will not freeze to death). The average flower temps are around 70f for germination. Herbs tend to require much higher germination temps and that is why many people have difficulty growing them from seed -- Rosemary being one of the worst: Rosemary (Rosmarinus officinalis) 80-90 °F (27-32 °C). If you plant your seeds before OPTIMAL germination temperatures are present, you do risk rotting the seed if the ground is very wet... but for the most part, the seed will just lay dormant until all of its germination conditions are met- then it will germinate.
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Showing 11 - 20 of 38 comments
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Sunflower seeds are very easy to grow. I have grown them for a few years for looks, but being a very experimental gardener, I plan this year on growing them to semi-support my tomato plants. I have a few varieties but have chosen the Giant Russian variety to take on this job. They not only look great in the vegie patch, they attract bees and produce lots of seeds (for eating). I'll just have to watch it that the birds will help themselves to the seeds (and the tomatoes).

- Jaci

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This planting guide is a general reference intended for home gardeners. We recommend that you take into account your local conditions in making planting decisions. Gardenate is not a farming or commercial advisory service. For specific advice, please contact your local plant suppliers, gardening groups, or agricultural department. The information on this site is presented in good faith, but we take no responsibility as to the accuracy of the information provided.
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