I read that if you put a rose stem in a potato and plant them it will begin to grow. I was wondering first off can it be a store bought rose stem? And do i eventually have to remove the potato or will it rot away or even grow?

I'm afraid this is a gardening myth. The potato will grow, and the rose probably won't. It's hard for a little rose cutting to compete with a potato for moisture and nutrients.

Hi & welcome!

Agreed, though I do think there may be a historic truth there, from settlers in covered wagons wanting to try to grow roses in their new locations. Sticking the cutting in the potato could keep it from desiccating for some time, possibly having taken root by the time the trip has ended. Although it may have sometimes worked, there's nothing about doing this that would cause it to be a preferred method for attempting propagation, unless your cutting does need to spend a few weeks in a covered wagon. This old tale has gone viral for some reason this spring, but should probably remain a discussion about history, and example of the determination a gardener can have. :+)

Roses do take root easily from cuttings though, stuck in the ground about 6" deep. You can also ground layer them by bending a branch to the ground, lay a brick or rock on it to hold the stem in contact with the soil, ignore until root ball has formed under rock/brick.

IDK about the viability of rose stems obtained as bouquet entities. There's probably some florists who visit here. Hopefully someone with that kind of experience will pop in & help out on that.

The stems of roses grown in hothouses for the cut-rose industry often are treated with a chemical that prevents rooting so that the blooms will last longer and the roses won't develop any "unsightly" roots in the vase.

Tiffany's absolutely right about the covered-wagon origins of this practice. The rose cuttings were plunged into potatoes for the long trip, but I'm sure the pioneers removed the roses from the potatoes before they planted them.

That's just gunna rot!

I root them by taking a cutting that's about as big around as a pencil, cut it back to one or 2 nodes.
Find a shady spot with relatively loose soil, push the cutting a few inches into the soil, then cover that with an upended mason jar.
In a month or 2 it'll start growing, it has roots at that point, remove the jar and water it weekly for the first few months.
It's the most fail safe method I've used!