Making cupcakes look like flowers is easier than you would think! Roses are very easy as seen in the Cupcake Bouquet and Hydrangeas are not really any harder.
The trick to piping flowers that look like hydrangeas is getting the varied colours that simulate the multi-coloured tones of the tiny petals. That, and using the right piping tip; a small closed star tip (Wilton #224). Unlike most star tips, this one has a small wire in the center of the tip that helps separate the icing as it is piped.
Piping tips are easily bought at many craft stores for just a couple of dollars and investing in a few basic tips is well worth it — even if you only bake occasionally.
Hydrangeas come in a variety of colours to choose from so pick one base colour such as blue. Make your buttercream or Swiss Meringue Buttercream (which is what I typically use). Start by tinting all of the icing a very light shade of blue. remove half if you want two shades or a third if you want three shades. Two is usually fine but three can add more depth to the colouring. Add a bit more blue to the remaining icing to create a slightly darker shade of blue. If you are doing a third colour, remove half the icing once again and darken the remainder once again. You can also add a bit of a different colour such as red to make the blue a bit more purple if you want.
With the different shades of blue icing place a spoonful at a time in the piping bag. Try to get the colours to be side by side and alternate the shades as you fill the bag. For a really easy way to fill a piping bag check out How to Fill a Piping Bag with No Mess and No Fuss.
Gently squeeze the bag to start the flow of icing. With all of the cupcakes lined up and ready to go (or on a bouquet) start by simply piping at a 90 angle to the cupcake. Be sure to randomly pipe enough small star shapes to fully cover the cupcake. The colours should be coming out side by side to create the variegated look of the petals. Work quickly so that the icing does not become too warm or else it won’t hold its shape too well. Piping like this surprisingly enough will give the look of hydrangeas!