ONHN’s goal is to provide healthy and hearty vegetation. The containers used by ONHN were chosen because of the root growing features along with ease of planting while being relatively inexpensive to purchase. The below link is from the Native Plants Journal, October 2010 which provides a study on plant containers for restoration projects. As you will read the Stuewe and Sons Styroblocks and Treepots provide the key features for air root pruning and deep root development!
While the Willamette Valley is a slightly different ecosystem than what we have in Ohio the same general principles apply for habitat restoration. Below is a link to an October 2011 article from Oregon State on riparian restoration including the value in using plug style vegetation.
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The last paragraph in the Discussion says it all. ONHN pre-soaks and encourages fall plantings for successful plant growth.