what you need:

- photoshop (i’m using 2018)

first, open a square document in photoshop and fill it with rectangles of the color that you want! (x) i’m not doing the traditional bright colorful one, but you can choose any colors!!

then, add a gaussian blur  at filters (the number depends on the size of your image) and go to filter - distort - polar coordinates and choose ‘’rectangular to polar’’ (x)

after that, make something like this with the liquify (if your version of photoshop doesn’t has the tool that I used in liquify, you can make this effect with the normal/first tool)

save it and blur the color that is sharped (like this) and open the liquify again!

now it’s the last steeep! you only need to use the normal tool (the first) to mix the colors like in the tie dye effect! mine is like this!!!

to finish it, with the marquee tool, select your image and make a pattern with it at edit - define pattern!! :D yaaay!