When I visit storage how can I use flowers and shrubs to my aďvantage?

When you visit your storage, you can store low-flower value items so that you have space on your island for high-flower value items. This allows you to progress in the game. If you have too many low-flower items, you will run out of island space. Aim for high-flower value items for the greatest advantage.

Just to be clear, bushes and shrubs that you receive from other players, cannot be stored. They can only be kept/moved on the island or cleared away for a gift.