Sun Flower pot size ?

Thanks a lot @GrowingGrannie , @Creepy_Steve and @m0use for your reply, Of course if I could grow in full ground, I'll do it, But my space in full ground, he's only few hours sun per day.. Yeah I've checked on Google, and I've seen could be grow in 15-20 l pot, and see various strains, but no idea of mine. I see you're all said me the biggest is better, thanks for your help.

Ive grown sunflowers before outdoors in 5 gal pots its fine, I also tend to grow dwarf varieties, like dwarf teddybear. Even grown them in smaller ones about 1 gal in size. Just have to water more the smaller pots. The plant will grow to the size of its surroundings. Obvy larger ‘giant type’ plants I’d aim for bigger if possible, 10 - 20 gal, width is more important then depth and you will need support for the big tall ones. I’d mix in a good helping of compost into the medium as well as some extra calcium if u have it, powered egg shells would work. Given its a container fertilize every two weeks. A aged / composted manure is great, I like acti-sol for this. Two other tips to help, sunflowers love boron, just before flowering water in some borax, or another form of boron, bout 1 teaspoon per gallon n about 1L a plant of that solution, also use grass clippings or hay as a splash guard in the pot once the plants clear the surface from sprouting. Good Luck!

i bet a similar mix that works well for marijuana will work well for the sun flower. i know morning glories are very happy with the same ratio and typical concentration i use for my marijuana plants. this can vary, but similar plants like similar things in general. pot size.. i'd google for soem plant specific info.. some like to drive deep, some like to spread out near top.. might impact the size/shape you want? going a little overboard on size will be safe and avoid the effort :P

@GrowingGrannie thanks for your reply buddy, but I mean about sun flower 🌻, not cannabis plant 😁

I grew outdoors last summer for the first time... and I grew in pots rather than put my plants in the ground. My BIGGEST mistake was to use pots that were much too small - I only used 5 gallon (19L) pots. The roots badly overheated in such a small pot and were the major contributing factor in losing the entire grow to bud rot. This year, I'm going to be putting my plants in the ground - but if that's not possible for you, the SMALLEST pot I would recommend would be a 56L - even a 75L... especially if you're growing a photoperiod (I was growing autoflowers)... The extra soil around the roots will help keep them cool... And, btw, if you want to see the volume of roots these plants produce, take a look at my harvest week of Creme de La Chem - I've got a video showing how the roots (in DWC) filled up and took on the shape of my 5 gallon bucket... Good luck!