It is best to let the flowers dry naturally on the plants which usually happens from August through to October. You will know they are ready when the petals take on a vintage look, or when they mature to the colour of parchment paper, often with tints of pink or green. The flowers may also feel papery.
You can make your own wreath base or buy a woven wreath or wire wreath, and secure the stems of the blooms to it with floral wire. Make sure to tie a length of ribbon to the base before starting to form a hanging loop for your finished masterpiece.
Cut the flower stems just above a leaf node where you should notice a bud or two. You want to leave those buds on the plant so you have blooms next year. Do not strip your plant all in one area, pick flowers from all over the plant, this way you will not end up with a bare spot!
You will need stems to measure at least 15cm (6”) to work with. Cutting stems which are too short will make it difficult to attach them to the base.
Remove the leaves on the ends of the stems. The leaves at the base of the flower can remain if you like to add a little foliage to the arrangement.
Thread each stem through the wreath base and secure with wire. Repeat with the remaining blooms until the wreath is covered.
You can add flowers and foliage of late-blooming shrubs and plants such as Skimmia, Hylotelephium (formerly Sedum), heathers, sprigs of ivy, and any foliage which is taking on an autumnal hue like Berberis or Cotinus (the smoke bush), to make a fabulous autumnal wreath.
As the wreath dries and ages, the Hydrangea blooms take on more muted, romantic tones of dusky rose and violet.
The wreath should last you for several seasons if it is protected from the weather and can be stored in a cool, dry place when you need to make room for your Christmas wreath.