Choose a vase, bucket or decorative container to store your greenery. Get creative with your container and try using something that is brightly colored or uniquely decorated, such as a fancy vase or jar. Decide on which container to use based on the shape of the plants. For example, use a vertical vase that will accentuate the height of the plants. Alternately, a horizontal vase is better for shorter plants because then they won't be overshadowed.
Place floral arrangement foam in the bottom of the container. If you want, use a hot glue gun to apply a small amount of glue to the bottom of the foam before placing it in the vase.
Arrange the greenery by poking stems through the arrangement foam. The foam should be sturdy enough that the plant will not fall over. Arrange taller plants in the center and have shorter plants at the edges of the vase so that they can stick over the sides. This will create a balanced arrangement. Continue to add greenery until the shape is filled out and the size of the arrangement meets your expectations.