When attempting to preserve flowers with silica gel, you need to follow a specific procedure. You should get a list of items that you would require for this purpose so that you can go ahead and work on preserving your flowers without missing one thing or another.
You will need flowers that are fresh cut together with Silica Gel as well as an appropriate container to work on as detailed at secretflorists.com. Not all types of flowers would work when trying to preserve with Silica Gel. So you will need to identify those that will give you best results.
Roses are usually among the best of flower types that you could use when looking to preserve them. What you do is, line the bottom of a container with silica gel and you drop a flower in. Take a spoon and then kind of shake it in the middle of the petals while that's in there and then take it in.
What you don't want to do is just pour the gel on top of the flowers because that will open the blooms and then you'll kind of have a flat flower and you don't want a flat flower. You want it to be 3D and its going in a 3D shadow box. You want to build up along the sides so that you're not crushing anything.
Silica gel is not cheap but it is reusable so if you have to preserve more flowers in future, you will still have some silica gel to help you preserve those flowers provided that you used it correctly and stored it the right way. You can do them in a bunch of different ways. For further information on preserving flowers, you can check this site out.