Here is this year’s photos from the Bartlett Tree Lab study comparing different planting methods for urban trees. For comparison, check out last year’s set. And for a fuller chronological picture, you can see each year’s photos, from 2004 onward, here.

This independent study was set up by Dr. Tom Smiley to test how well trees fare in different growing media. The trees are monitored and tracked from year to year to measure their leaf extensions, height, DBH, and more.

The research plots were set up so that that 12 trees planted grown in a suspended pavement system (which is identical in performance to the Silva Cell), 12 trees were planted in a stalite/soil mix, 12 trees were planted in compacted soil, 12 trees in pure stalite, and 12 trees in a gravel/soil mix. All trees had access to 189 ft³ of growing medium.

Bartlett Tree Lab study is not sponsored by DeepRoot. Bartlett is an independent lab that chooses their own test parameters, conditions, and technologies. 

All images courtesy of Tom Smiley.