I've planted teddy bear sunflowers in different containers. I haven't had issues with hindering other plants as you describe, unless you mean issues with sunflowers shading the shorter plants. I grew teddy bear, nasturtium, and lobelia in a container, and all seemed happy.

cheers,
Norabelle

Yup I grew tithonia's in a container too, the got to be about four foot in there. I love those pale yellow ones too.
{{gwi:369525}}

OK, great, I will plan on putting them in the patio containers then. I forget where I read about sunflower sometimes keeping other plants seeds from germinating...maybe it's just a garden myth. But it would be nice to have something tall-ish for these patio containers anyway, so I'll go ahead and plant them in those.

I looked up the seeds I have some more, and found some photos of ones that people have grown. The kind I have seems to have wispier stalks and don't grow as large as the standard gigantic sunflowers, so I think they will be OK and not blow over in the wind in the container.

I'd never heard of a teddy bear sunflower...looked it up...they are so cute! Maybe I'll grow some of those. floodthelast, the tithonias are so pretty too...I've been really enjoying your flower photos. So inspiring!

So many seeds!!!! It's hard to resist wanting to plant more...

Thanks!

I don't know if the plants themselves hinder anything, but I'm told from feeding so many seeds to the birds and squirrels in one place over the years, the shells release a chemical that does inhibit anything you try to grow there.

What I'd do is when the seeds are ripe, harvest all of them. Cut the heads off, dry and feed to the birds someplace where it won't hurt the soil, what you don't save for next year. If the birds eat out of the seed heads or seeds that spill on the ground, you might have the same problem I have.

I'd been doing that in one spot for years, the shells went down on the ground, couple places doesn't matter, but one spot, I'm waiting to see if the stuff leaches out, sowed some test seeds, admit I may not have watered enough, but the plants seemed sickly to me. Even not many weeds grow there either.

I'm still adding to the problem by using up the last bag of the larger striped seeds I was buying for the birds and squirrels in winter, was buying 7# at a time.

Hi, yes, I read the same thing about the weeds too. I think it said sunflowers are good for weed control, like if you have a weedy area, weed once and then plant sunflowers and you won't have as many weeds again? Not sure if that is really true, but it sounds like it could be that way from what you're describing. I haven't grown sunflowers in many years, so can't remember if they had this effect or not.

Maybe it depends on the kind of sunflower...or the kind of plants you try to grow near them. I think my lemon-y/white sunflower seeds are some kind of hybrid...they may not have the same effect on surrounding plants & seedlings. I still think I'll go with the container just to be safe.

Anyway, the photo on my seed package does look really pretty, so I'm excited to see if they germinate!

Been doing a little reading, not much. There ARE people who know more but aren't likely to see your thread here. Evidently sunflowers are useful for decontaminating from lead, pollutants and even radionuclides. If you want to read more, google sunflowers soil remediation. Also do a search here on GW for sunflower seed hulls. The word for the weed inhibitor is alleopathic, black walnut, sycamore, sugar maple, eucalyptus, others. I'll post the link because it is interesting, mentions sunflowers in the comments but can't find the comment that led to it.

I've got one fairly sunny spot just north of my seed pollution (no possibility it's from seed hulls) where nothing has grown for years, suspect maybe my son or someone dumped some old oil or gas oil mix there. We had a heating oil spill when I was a kid; until we moved 7-10 years later, same result, totally barren.

Getting soil tested is a hassle and would be more involved than the basic one for lacking of essential nutrients, probably cost more. I really hate to dig it all out, dispose of it and replace with fresh soil but may have to.

I've got a free pack of sunflower seeds from years back and could use a few of my new good ones to test that spot and see what happens. If the sunflowers do grow, will get rid of the plants although toxins evidently are absorbed by the plants and don't get into the seeds. I wouldn't want to harm birds.

I don't have any reservations planting sunflowers for one year in my soil and deal with the heads. A lady grows them in her strip between the sidewalk and street for a few years I've noticed now, they still grow but not a nice variety and/or scraggly, probably need some water, too.

Here is a link that might be useful: Allelopathic plants: natures weedkillers

Thanks for the kind words, I wondered if that was you sifting through my sunflowers. :) You are right about them being thinner than the big ones, I planted many in the same spots and some in containers. All the ones I did were five foot at the tallest and did well together. I saved so many seeds and collected a bunch more from my Mother's. I gave her the tall ones and got to go over to take pics later in the season.
I am excited to see yours grow too.

I posted a quote from the McGill University's website posted below.

The page is about feeding/deterring birds, but mentions the sunflower seed hull issue. The sunflower plant isn't the problem*, but an abundance of hulls is.

*Sunflowers are actually a great companion plant for certain veggies. I am inter-planting sunflowers with my beans and cucumbers for this reason.

"Good sanitation is necessary. Every once in a while, disinfect the feeder with 1 part bleach to 9 parts water. Occasionally rake up the spilled seed husks as they can build-up and mould. As well, husks from black sunflower seeds have an alleopathic effect on plants, meaning that they inhibit their growth chemically. If you have these in your birdfeeder, make sure you clean the husks up regularily, as they can readily kill your grass or other plants if they become numerous enough."

Cheers,
Norabelle

Here is a link that might be useful: Attracting and Detering Birds w/ comment about sunflower seed hulls

Well, it sounds like the hulls are the culprit here, talked about it on another forum here on GW but can't remember which one a couple years ago. I suppose I could clean them up, sure have swept enough off the steps. No I can't really. In the winter on the feeder in the back, not using it, since I had the new stoop and walk poured, I don't like to go out there as the ice gets really bad. I will only salt the stoop as I don't want salt washing into my soil. I am only able to take my garbage out if I'm lucky about every 3 weeks when there's snow, and it doesn't melt there for the whole winter, it's that bad how it is further out back. I did manage this last time, but had to be super careful.

In the front, I just scatter them on the stoop because it's the easiest and safest for me in the winter, then they fall in the snow, not picking them out of that. But maybe I could check tomorrow for leftovers.

Thanks for posting the links to those articles everybody! Very interesting...it does sound like the sunflower seed hulls are the material that contains whatever chemical that keeps other plants from growing.

I'll post sunflower pictures when (if) my seeds sprout & grow!