SimpleSoil
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Mammoth Sunflower Bolting

I sowed several dozen mammoth sunflower seeds into one of my beds on August 15. This bed had just previously had manure tilled in and fresh mulch when the sprouts were a few inches tall.

Daily watering, 8 hours of sunlight a day, temperatures around 90/79 High/Low. Florida Zone 9


They're about 12-18" now, but they have all begun to form flowers, so I'm going to remove them and plant something else there. What caused them to flower so early?

Bobberman
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Dry ground or too close planting would cause them to go to flower. Also planting them in the dead of summer may cause that I suggest you plant the ones that have like 40 flowers on each plant. The mammoth i never liked! I think the worlds record is 900 plus flowers on one plant! I had a 12 foot plant a few years ago with over 40 on it!
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zanthal
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Re: Mammoth Sunflower Bolting

Whoa, 40 blooms on one plant? I didn't know sunflowers did that, I thought it was just one bloom per stalk.

I have another thread about Mammoth Sunflowers going ... please do respond:

https://www.helpfulgardener.com/forum/vi ... 68#p340468

imafan26
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Re: Mammoth Sunflower Bolting

I have never had a mammoth have more than one flower either. Sometimes they will not attain their full height especially if they were kept in the pot too long or did not get enough water.

I do grow other sunflowers that have multiple flowers but they are much smaller heads. Lemon queen, Autumn sun, and Chianti are the other varieties I have grown. Lemon queen has worked out pretty well for me.
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rainbowgardener
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Re: Mammoth Sunflower Bolting

My guess also would be that it has to do with temperature. That is what leads to early bolting in lettuces etc. (We don't usually talk about sunflowers "bolting" because blooming is what they are supposed to do. Bolting means going to flower/seed in things like lettuce that we don't want to do that.)

Not the mammoth, but many of the smaller sunflowers are multiple blooming:

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catgrass
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Re: Mammoth Sunflower Bolting

I'm in zone 9, too, and my sunflowers were especially slow this year. My mammoth (only one came up) got real tall, but the flower itself was small. I always plant several kinds, but this just doesn't seem to be a sunflower year for me. Lemon Queen and the red flowered ones usually make several stems with multiple flowers. I plant them all, cause I want them to be a stink bug trap so the stinks will leave my tomatoes alone.
zone 9 Southwest La.

imafan26
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Re: Mammoth Sunflower Bolting

I did not know about them being a stink bug trap. I use them to provide nectar for bees and beneficial insects and because they are so amazing especially when the kids come by.
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ElizabethB
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Re: Mammoth Sunflower Bolting

Simplesoil - welcome to the forum. I think you planted too late and the heat is causing them to bloom prematurely. Good luck with moving them. They do not transplant very well.

In south Louisiana sunflower seeds go in the ground in March. By August they have bloomed and the heads are drying - ready to harvest seeds. If the birds and squirrels leave any.

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applestar
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Re: Mammoth Sunflower Bolting

I'm guessing the heat and/or shortening daylight.

This is OT I think, but I wanted to comment on the multi-headed mammoth.
This volunteer I have growing has a sturdy speckled trunk that is about 2" in diameter, holding up the multi head well without any support. I'm guessing it's about 8-10 feet tall.
image.jpg
Except for the speckled trunk, it looked like it would be a normal single headed mammoth initially (the biggest head -- already fading and on the other side -- is about 10-12" across). Unless it was a seed dropped by birds, the seeds would have come from small flowered multiple that I grew the year before. The funny thing is that I *thought* I planted from a mammoth head of seeds I had saved.

Only explanation I have is that the original mammoth had been cross pollinated with a small-flowered multi-headed variety -- I think it was out of "sun samba mixture". I like this one a lot. I'm going to try to save the seeds from the first to bloom biggest head and see if the interesting traits this one showed will repeat in the next generation.
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catgrass
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Re: Mammoth Sunflower Bolting

How cool! I've never seen a large one bloom like that! Another good sunflower type to plant is tithonia. Makes tons of orange flowers all summer long and the bees and butterflies love them. Easy to grow-reaches about 4-5 ft. tall and multiple branches.
zone 9 Southwest La.

zanthal
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Re: Mammoth Sunflower Bolting

Tithonia ... check!

you know applestar I got the idea to grow the Mammoth variety from four separate blooms that were growing on the side of the road (someone reclaimed some sidewalk soil in front of their house, obviously), and all of them are single blooms, they're huge and starting to bend over from the weight of their seeds.

This probably is OT, but I still want to ask, what makes them end up as either multi-headed or single-headed, and am I right in thinking that the multi-headed variety end up having smaller heads than if it were a single bloom?

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