Growing Sunflower

helianthus annuus : Asteraceae / the daisy family

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

(Best months for growing Sunflower in Australia - sub-tropical regions)

  • S = Plant undercover in seed trays
  • T = Plant out (transplant) seedlings
  • 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 10°C and 30°C. (Show °F/in)
  • Space plants: 20 - 45 cm 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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20 Sep 20, Anita (Australia - cool/mountain climate)
When is the best time to plant giant sunflowers in the Southern Highlands, NSW?
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27 Sep 20, (Australia - cool/mountain climate)
Go to cool/mountain climate zone and check the planting guide at the top of the page.
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25 Aug 20, Josie (Australia - sub-tropical climate)
Hi! Wondering if it’s too earlie to plant giant Russians , I’m just north of Byron bay in the mountains, nights are still getting below 10 degrees and the soil in my garden is red clay type soil mixed with soil improvers, too cold still?
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26 Aug 20, Anonymous (Australia - temperate climate)
I'm sub-tropical and I have seeds germinating now (night temps av around 9-10 (7-14) and day temps around 23-24 (21-28)). Hold off for another week or two and then give it a go. We may have another cold period before winter is finished.
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05 Jul 20, Ann Carson (USA - Zone 8b climate)
What kind of soil best for sunflowers? I planted afew times that begin growing then rodents eat top of sunflowers. Same as radishes too.How do i solve the problems?
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01 Jul 20, Emma (Australia - temperate climate)
Hi, I was hoping for some planting advice, how many seeds in each amount of soil?! Is it a good time to plant the seeds now in winter nice and deep to get the best results come spring time? Thanks Perth WA
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06 Jul 20, Anonymous (Australia - sub-tropical climate)
Plant seeds 50-60cm apart and rows 60-80cm apart. You can plant two seeds and then reduce to one after germination. If good seeds just one is required each 60-60cm. Don't plant until spring as you need a lot warmer soil than what it is now. Do not plant seeds deeper than what is suggested.
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12 Jun 20, Vicki Holley (USA - Zone 9a climate)
Looking for a monthly calendar to plant by for zone 9a. Was hoping to plant something in June? (Try here https://www.gardenate.com/?zone=115) Gardenate
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16 May 20, Thelma Jenkins (USA - Zone 7b climate)
Our area has a lot of wind, up to 95 in summer. Get some snow in winter. Would like to plant them along our fenceline around our 1acre. Zone7b.AZ. Any advice will be appreciated.
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04 Sep 19, margret botha (South Africa - Semi-arid climate)
can I plant sunflowers in wellington westen cape
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Showing 51 - 60 of 160 comments
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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.

- Celeste Archer

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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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