Seems to be a problem that comes and goes.

Various reasons given range from long drought period, not enough water during growing period, insufficient fertiliser, early onset of autumn.

When growing giant sunflowers, soil preparation should include deep digging to loosen soil and to allow for better absorption of fertiliser. Giant sunflowers can have a taproot 4 feet long – this is why the seed is best planted directly into growing position rather than trying to raise seedlings in pots. A slow release fertiliser should be added to a depth of 8"-10".

Lack of pollinating bees could also be a factor and the proximity of other sunflowers.

It’s a real bummer to grow something like a sunflower to its maximum height and then discover that the shells are empty.

I have since googled ‘sunflower empty seeds’ in various combinations of those words and it is not an unusual problem.

Nobody seems to have a specific answer that I can find.

I gave up on growing the big varieties and now grow the (what I call) clumping kinds such as ‘Bronzed Aussie’.

I’ve also had that problem with Sunflowers! You are not alone by any means! I had a head exactly as you described only it was about half the height of yours. I cut it off a week ago & put it in the greenhouse to dry off. I’ll have a look tomorrow & see if the shells are empty.

Not many flowers when I took that photo but lots are opening right now!

It would seem that for every seed there has to be pollination. Perhaps its the bees that didn’t get to all the stamens? Sunflowers are one of my absolute favorites in general.

@Prickles, no source just trying to think logically. But I did find this….

Question

So, I’m attempting to harvest sunflower seeds from some giant sunflowers I planted a coons age or two ago. Unfortunately, there’s nothing inside the seed pods!

I believe the sunflower was a ‘giant’, it may have been a mammoth though (actually it may have been both as I just used some old seeds my mom gave me a year or two ago and threw away the packs). Also searching for this info on the Internet is hard since ‘giant’ is also a brand of sunflower seeds (apparently not coming from giant sunflowers)

Should there be anything inside the seed pods to begin with? i.e., whether or not certain sunflower varieties are purely ornamental."

Answer
“I have had that happen to me before, and I found a very small worm, resembling a minature corn ear worm. They were boring very small holes in the shells and eating the insides out. I do not know what they are but they can be controlled the same way as corn ear worms. They can do real damage to a crop of sunflowers.”

source: gardeners and landscapers beta – ahem…. has similar attributes as Myfolia – badges, etc. I promise I won’t go there again. Google gave me the above information that I thought interesting to the original question.

The worm theory sounds more plausible.

Does any one know any thing about Mexican Sun flowers? I bought the plant at a farmer’s market, planted it at the top of the garden. The plant did really well it out lived the four other sun flowers I planted. My question is where are the seeds you save? The plant has red pedals that are falling off now, so where are the seeds? The sun flower is still thriving, I would like to save some seeds. Ellen from Georgia

By mexican sunflower do you mean tithonia?

It looks like titonia to me. Not a ‘seedy’/true sunflower as we know but a pretty, drought loving plant. It grows BIG.

So what I am understanding then, Ellen from Georgia does not have a true sunflower but a confusing common name to elude she does. Those silly common names. They get the best of us sometimes.

usually you have to let the flower dry and leave it for a while to get seeds. But they wont be true sunflower seeds, so probably not edible.