Dried items, place them where it’s less humid, avoid moisture, direct sunlight, and windy place.
Pampas grass sheds, a light coating of hairspray can be used every 6 months to reduce the shedding.
They should last for a few years under proper care!
Please note that the images shown are solely examples of a typical pieces. As they are natural products some variations in size, color, and shape are to be expected.