I found a basque in a underwear sale and dyed it green. Be careful though as man made fiber will not dye but it gave a good effect on the lace of the basque.
I bought fake ivy leaves from a florist and individually sewed the ivy leaves to the front of the basque and one of the straps so they were overlapped.
I bought thick elastic and thin lightweight green fabric for the skirt. I cut out triangles of different sizes from the fabric and sewed them into the elastic. I chose to make the skirt quite thin but more fabric could be added to the skirt if you prefer.
As the elastic was thick I made a belt to cover it up. I got thick green ribbon and sewed ivy leaves to it then attached poppers the edges so it could fasten. I got a cheap hairband and sewed ivy into it.
I wore the Homemade Poison Ivy Costume with brown tights and green sandals and lots of green makeup. I already have dyed red hair so I didn't need to get a wig but you can buy them from the internet.