This design is pretty easy to print and requires no support material, not even for the stem with the spines.
The only thing you have to keep in mind is that we want the stem to fit into the rose and it's base. If your printer is perfectly calibrated it should fit perfectly because there is 0.1mm of space between the whole of the base and the rose and the stem. This is not my case so what I did to be sure it fits perfectly and there is no room between the three parts is to heat a bit the extreme of the stem and when it gets malleable just push it through the base and into the rose. This way it gets sticked into the hole and when the plastic cools down it expands a bit so the rose and its base cannot be moved anymore.
Finally to bend the leafs of the base you can heat them with a hair dryer and they will start curving to themselves.
For me it worked with my default printing speed which is 50mm/s for the outer wall.