Team Tree Blog



At the nursery we have almost finished a job that has been a standing order since last fall. This is our pot-in-pot system. It is basically a field of plastic pots dug into the ground. there are 168 15 gallon pots, and room for two more rows (28 per row) of larger 30 gallon pots. The pot in pot field sits in the southeast corner of the nursery, going along the fence. The system is used to help trees survive the winter. All of the trees in our nursery need winter to maintain their life cycles, but they also need to maintain certain temperatures. If their roots were in the ground, they would be much warmer than when they are potted above ground, without insulation from the soil. The pot-in-pot system allows us to have trees in the ground, but also keep them mobile for fall and spring plantings

After we finish the pot-in-pots, the new ones will start to look like the olds ones, the next steps being turf, wraps, and irrigation. We cover up the patches in between with grass, spaced so that a mower can ride between the rows, and lay an irrigation line with drippers for every tree. Out of the trees that were in there last winter, only a few died, and the system is working very well. We hope that it will still be there in 10 years.

A special thanks to Matt, Jonathan, Charlie, Chad, and the Nicks.





by Nick Neylon

Tree of the Week: Chinese Catalpa


This week’s tree is the Chinese catalpa (Catalpa ovata). They are easily recognized by their long thin pods and their heart shaped leaves. They differ from the native variety by having longer pods, and purple tinted leaves. Just recently we planted a few flats of them in one of our fields, replacing the winter kill from last year.

Chinese catalpa is obviously not native plants, but they work well in Minnesota, and have been successful in urban environments.  A good example is still flourishing next to the stone arch bridge – 10 years after transplanting from our research nursery here at the U of MN. They grow in the USDA Hardiness Zones of 5-9, going to -20 or -30 F. The Chinese catalpa is a little squatter than the southern catalpa, growing to 20-30 feet. It was a special tree in china because its wood was used to make the bottom of the qin, a traditional Chinese instrument.




P8170348.jpgA full grown Chinese catalpa, down near the Stone Arch Bridge in SE Minneapolis

P8170347.jpgTeam Tree under the same, a tree that left our nursery 10 years ago

by Nick Neylon

Former Champion Willow Genetics Saved

Heritage Black Willow

American Forests is the oldest conservation non-profit organization in the USA. They have a project, started in the 40s to catalog, protect, and preserve the largest trees living in the United States. They pick around 750 champions every year, amazing and awe inspiring giants of arbor culture. The trees include urban trees, but also many giants left untouched in virgin forests. They focus on the biggest and best, but they say on their site that “regardless of size, all trees are champions of the environment.”

 One of the trees, a former champion from the year 2010 nominated by MPRB arborist Kevin O’Connor, comes from our very own Hennepin
County. It was a Black Willow, Salix Nigra, with a circumference of 384″, 64′ tall, and a 73′
The tree died, and had to be cut down, but it was an amazing specimen. Chad had time to get some cuttings from the tree before it died. They took root, and just like willows are know to do, they are growing quick and wild. With some structural pruning, they are looking great so far. These trees have some very large shoes to fill, but hopefully they can join the ranks of some of Americas largest trees. Pictures of the new champion willows coming soon!

Link to the American Forests Big Tree page, a must for anyone who wants to see some amazing trees

by Nick Neylon

Como Golf Course

Burley w/ trees

Team Tree went to Como Golf Course on another bike excursion. The site is one of many research site we have that examine how seedling trees develop in tree tubes. Jonathan just bought a new bike trailer, and we loaded it up with some little trees and a few tools, and headed over to the golf course to check up on trees, and replace a few that didn’t make it.

When we got there, the turf manager greeted us and let us borrow a golf cart to get around the course. He said there had been a little vandalism recently, but all of it was harmless to the trees. Most of it was obscenities spray painted on tree tubes, and there was a smiley face painted on an elm tree.

The golf course was one of our higher-stress outings, as Jonathan and I often got confused about which way people were hitting their balls, and heard “fore!” a few times. Luckily we didn’t get hit, and the turf manager said it comes with the territory. He hasn’t taken any serious hits, and that’s with a lifetime on the course.

The trees were looking good for the most part, aside from a few dead buckeyes here and there that we replaced. The turf manager said that some of the older trees on the course would have to come out soon, and I was glad we could help out keeping the course well stocked with shade trees.

Jonathan checking on trees

Les Trognes…und der Dachplatane

Yesterday at the research nursery we had a unique and fun opportunity to do some pruning work with Louise Levy of Levy Tree Care in Duluth, MN.

Besides her work in Minnesota as an ISA Certified Arborist, Louise has had many opportunities to travel and work in France, Belgium, and Germany – studying and practicing pruning techniques and styles that are both very old and, in many cases unknown to American audiences.  We’ve been talking about “alternative” pruning and training practices for some time, we finally brought it back home!


Dachplatane - Before

One of the first techniques we experimented with is called Dachplatane, which means “roof tree” or “umbrella tree” in German.

While normally applied to a London Plane tree (Platanus x acerifolia) we tried it on a Northern Acclaim honeylocust; definitely not a direct comparison, but the tree was already moving toward this canopy structure – and additional work made sense!  One interesting and inspiring approach to this tree was Louise’s desire to work with existing leans or bends (due to wind) rather than our typical “pull ’em up straight” mentality.  The resulting tree is interesting and should provide for many years of discussion and continued experimentation!











Dachplatane - After






Here is link to a site Follow this link to a website showing the steps for creating Dachplatane (in German).  

This also shows the support structure used to create the “roof”, which we have yet to install.











Tower Poplar - Before







Now, moving on to pruning practices seen commonly in Belgium and France, we chose a “volunteer” Tower poplar (Populus x canescens).  This tree is a root sucker from a parentright next door and almost begged to join in the pollarding party!










Tower Poplar - After







Jonathan, one of our summer research assistants tested his saw blade with this foreign, yet exciting, method of pruning!

We’ll be sure to continue the intensive and recurring pruning required to establish the callus/woundwood heads on this tree!








Black Alder - Before






Our final subjects included a couple European black alder that had severe winter kill last winter. 

Lacking their definitive central leader and upright habit these trees were great candidates for something new and different!














Black Alder - After

Using techniques usually described to create “Les Trognes” in Belgium and France, we brought these trees into a new light and hope to have many more years

to follow their progress and continue their work.

PLEASE NOTE:  This should be considered experimental work for our region.  We are working with species not normally used for these techniques and are interested in testing their suitability for success! 

These pruning and training practices have undergone centuries of practice throughout Europe – but on native-European species that have a very long track record of success. 










We’re testing local species and varieties, hardy to Minnesota and the Upper Midwest to track and test both their response and performance after this work.  Please check back often for more updates!


…and one final shot for inspiration!

Les Trognes in Paris (photo courtesy of Russell Kennedy)

Les Trognes - Paris


by Chad Giblin