Recently in nursery production Category
On Saturday June 8th, around 30 volunteers helped plant baby oak seedlings that will hopefully take the place of their parents as they slowing start to decline from age.
Designated as a park in 1908, Newell Park is one of the oldest parks in St. Paul. One of the most notable features that separates it from other parks in St. Paul are the pre-settlement mature Bur Oaks that create a dense canopy over the entire park. Unlike in a natural system, regeneration of new oak trees from fallen seeds does not occur due to the heavy use as an urban park. In efforts to regenerate oak trees in Newell Park, we teamed up with the City of St. Paul Forestry to plant baby oak seedlings germinated in our greenhouse from Bur Oak acorns collected in the park. For now, only a small wooded area located in the northeast corner of the park was planted with baby seedlings (shown bellow). In addition to the oak seedlings, bare root Carpinus and two different varieties of Amelanchier (Serviceberry), both native understory species, were planted on the reNewell site to further restore the park.
The image bellow shows the site after all the oaks were planted. Inside each of the white tubes seen in the image are baby oak seedlings. Tree tubes are commonly placed on seedling trees to protect them from the getting eaten by animals or stepped on by humans. Additionally, the tube acts as a mini greenhouse that encourages the seedling to grow faster and straighter. The tube is removed shortly after the tree grows out the top of the tube.
Instead of using a truck to transport the bare root Carpinus and Amelanchier and flat of oaks, we carried the trees down to Newell Park from the nursery using our bicycle trailers!! Bellow is a team shot taken before we started our ride to Newell Park
Check out this neat time-lapse video of our elm grafting process! Created by our very own J.W. Fillmore...and featuring American elm roostocks from our friends at Three Rivers Parks District Nursery.
This December Jonathon and I (Greg) trekked out around Minneapolis collecting cuttings for asexual propagation for the Heritage project and came across this champion black willow (Salix nigra). Willow is considered to be a short lived tree that is prone to decay and failure because it grows too quickly for its own good. That is a good thing if you need a large tree fast but not if you want a tree that will last longer than you. This champion willow is located right across from the main parking lot of Lake Nokomis by field #5 if you care to see it up close. The circumference of the trunk is 379 inches and it stands 70ft. tall with an average canopy spread of 73.5ft! What a monster!
Jonathon Standing IN the monster!
There is a lot of work we have to do around the nursery to get ready for winter. The trees we
grow expect, and rely on winter to come, but they are also used to being under the ground, away from the harsh temperatures of the surface during winter. They are also vunerable to animals who will nibble away their cambium, which, if it gets bad enough, will kill the trees. If a tree is small enough, animals will leave you with only a frayed stump.
When planning to keep trees alive over winter, you need to keep these concerns in mind: to keep them protected from animals, and also to keep them in enough mass that the roots don't freeze and kill the plant. In planning for this, you need to take into account the amount of snow you will get. If you put a 6 inch wrap on a tree and there is 2 feet of snow, the wrap is going to be a foot and a half under, leaving the tree exposed. For our nursery stock, we placed as many as we could in the pot-in-pot section, and for the rest, we packed them in with mulch and then wrapped the stems.
This week's tree of the week is the London Plane Tree (Platanus x acerifolia). The London Plane Tree is a stately shade tree growing to a height of 70 feet tall. The mature bark is a stunning pale grey with exfoliating brown bark. The leaves resemble the look of a maple having a palmately lobed leaf. However, unlike a maple leaf, the London Plane Tree has a fussy back, giving it a unique character.
Being a zone 5 tree, The London Plane Tree is not commonly seen in Minnesota as it is not hardy to the northern climate. However, there are a few London Plane Trees scattered throughout St. Paul and Minneapolis. The slightly warmer temperature of the cities is often just enough for the London Plane Tree to survive the harsh Minnesota winter.
In the team tree fields, we have three varieties of London Plane Tree, Exclamation!™, Columbia, and Bloodgood. All three varieties grew extremely well this season! It was exciting to see the trees grow from small 4-6 foot whips to a sizable 1" caliper trees (left image). This fall, we dug out most the London Plane Trees to prepare to plant in root trapper containers next spring!
The image bellow shows two of the four rows of London Plane Tree at the nursery. The lush, 12 foot strips of grass like plants growing in between the rows of trees are cover crop that team tree uses in all fields to keep the soil as healthy as our trees. The cover crop is a mixture of millet and buckwheat, both fast growing plants. The cover crop is used to maintain moisture in soil, reduce weed population, prevent wind erosion, and finally, increase soil organic matter. Often times, nurseries keep the soil bare by continuously spraying for weeds throughout the season to reduce the competition for resources. However, the benefit cover crop provides for the soil far out weights the marginal decreased caliper growth.
The vigorous growth of the London Plane Tree is quite typical for the tree. The London Plane Tree is often used as street trees in warmer climates due to the vigorous growth and ability to withstand high compaction and atmospheric pollution. The number of tough tree species for urban situations is becoming less with the loss of American elm to Dutch elm disease and the more recent loss of Ash species to emerald ash borer. Both American elm and ash trees were extremely common street trees due to similar tough qualities the London Plane Tree has. With fewer and fewer street trees to withstand the tough street conditions, it is important to test the winter hardiness of different tough trees like team tree is doing with the London Plane Tree.
Arborists from Minneapolis and St. Paul came today to pick up the new city trees. The pot-in-pot field is almost empty now, we sent out 3 truckloads from there, and the container area is almost empty too. It was a long day of lifting trees, and looking around at all the dirt rings left, where my summer work once stood, I had a slight case of "empty-nest" syndrome.
Jonathan and I are going to bike out to Armitage neighborhood soon to help get these trees in the ground with the proper research conditions. We are going to be doing tests on the effectiveness of soil amendments, or putting organic matter in with the trees, not just the usual boulevard dirt, and soil rings, which among other things makes it a lot easier to water the trees.
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.
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.
A full grown Chinese catalpa, down near the Stone Arch Bridge in SE Minneapolis
Team Tree under the same, a tree that left our nursery 10 years ago
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: