I've found this article on
planet green'site By Annie B. Bond :
I saw the most beautiful peach-red leaf today, one of the most beautiful fall foliage colors I have ever seen. This is a leaf I want to keep!
My mother had a trick she used to preserve the color in fall foliage leaves, and I have since seen this technique suggested in old folk formula books. It really works, and the leaves stay on the branches and keep their color for weeks. I’m happy to share this tip, and use it myself. Here is her secret.
All you need is a little bit of vegetable glycerin, water, and newly cut branches with colorful leaves. Just put about 1/2 a teaspoon into a vase full of water, stir, and then add the branches. With this, the leaves stay on the branches and keep their color for weeks. Refresh the water and glycerin every week. Pure vegetable glycerin is available in health food stores.
I'll give it a try!:)