I don't believe there is a hedge DIY. I think it goes directly to your Nookphone when you learn it. The ways to get it are:
-During nature day celebration (you can TT to them now, they started... April 23rd, I believe)- you just needed to do one nature day activity (planting trees, flowers, etc.) and you'd get it.
-Or, now you can apparently get it from buying enough flowers/bushes from Leif. I don't know the exact amount, though.