Step 1:
The rose papers vary from 15x15cm to 20x20cm.
Prefold over these four lines.
 

Step 6:
Fold the flap upwards.
Repeat steps 3 to 6 on the other side.

Step 5:
Press / fold the edges downwards / flat

Step 2:
Valley-fold over the two lines at the bottom-right. Then mountain-fold over the two diagonal lines and valley-fold over the two lines at the top left.

Step 4:
Fold the tip downwards over the green line

Step 3:
Prefold.

Step 10:
Fold the four edges upwards.

Step 8:
Repeat step 7 on the other three flaps.

Step 9:
Pull the model into a plus-shape, see next step

Step 7:
Fold over these lines.

Step 16:
The leaf papers are about 8x8cm.
Prefold

Step 15:
One rose is done....

Step 12:
Pull the corners on the left and right outwards, see large arrows. And press the corners in the center against each other, see small arrows.

Step 11:
Make the same two folds on the other side.

Step 14:
This is how the bottom should look.

Step 13:
Press and twist the bottom flat, see arrows.

Step 21:
Fold over these four lines

Step 19:
Fold over these two lines

Step 20:
Press the model flat.

Step 18:
Fold over these two lines

Step 17:
Fold over these two lines.

Step 22:
Prefold in half.

Step 25:
I used large rectangular wrapping papers for the stems. Fold in half a few times.

Step 26:
Twist / press the stem inwards over the whole length.

Step 24:
And one leaf is done....

Step 23:
Press the edge inwards with your nail / finger on various spots.

Step 27:
Glue or tape a few stem-parts together into one long ivy stem. Then glue the roses and leafs to the ivy stem.