Hi there /fa/, how would one go about making your own patterned clothes?

I recently found a leaf with a pattern I absolutely love (pic related) and I would love to make a coat or t-shirt or something with that design on it.

I know there is a site called Spoonflower which I am looking at, but my main concern for now is: how do I save this pattern? Do I just take a picture of the leaf and use that? Do I scan the leaf? Press it? Photoshop a picture? Obviously the leaf will die soon so time is of the essence.

Also, what material would I need? Cotton for tees obviously, but for a jacket or a coat?