First, I looked at a lot of Poison Ivy pictures. Ones of the character and other pictures of Costumes. I picked up a lot of good ideas as well as learned from the bad ones.

For instance, covering the entire costume makes you look like a cheap oversized house plant.
:/

I suggest not doing that...

So! For starters, I drew out what I wanted my outfit to look like. (roughly).

I took a lot of measurements, but I'm terrible at measuring so I do a lot of things freehanded.

I sketched out what shapes I'd be using as the bodice, sleeves, and the the little tails of fabric I'd use around the thighs to stitch on leaves.

I used two pillow cases that were light green.

I'm not big on blowing money on fabric when I can just use something at home. I'm a big reconstruction freak and soooo! I laid out one of the pillowcases and drew out my shape.

After that, I cut it out, turned it inside out and stitched up the sides.

Because the pillowcase fabric isn't stretchy or flexible really, I fitted it and then added on a zipper on the side so I could in and out of it easily.

I cut out two strips of another green fabric and made the straps.

And again, but wider and longer so these straps would hang off of my shoulders (kinda like petals).

I then took the other two shapes and stitched them along the bottom of where my legs are so that it isn't so revealing.

This is also where the leaves will be tooo

I used my bright yellow leggings so that I wouldn't have to waste anymore time or fabric.

I also made legwarmers out of the other green pillowcase and decorated it with ribbons and leaves...

Then I used three different types of fake houseplants I found in my attic to decorate my suit with.

I stitched on every leaf so that the fabric wouldn't be hard and only at the very tip where it would be if it were on a branch.

All around the legs and the chest.

Then I cut off three sunflowers. Two on one side of my leg and the third in the middle of my chest.

Finally!

I used the extra shredded fabric and just tied it all up and down my legs and arms.

It gives it that ivy feel, I guess.

I'll also be using more around my stomach area toooo just to make it look more plant like :)

And then there you go!