I had not previously heard of this “famous” tree that has been clinging to life in the DC Tidal Basin as the river has slowly drowned its roots, but I thought it was interesting that the National Arboretum will be making own-root clones of it rather than grafting:
The relevant excerpt:
The propagation process starts with clippings that arboretum horticulturists will take from the tree after peak bloom ends.
Zettel demonstrated the cutting-and-rooting process for us, using a baby cherry tree in an arboretum propagation greenhouse.
“What we’re looking for is new vegetative growth,” Zettel said. “So this is new growth that appears on the tips of the branches in the spring, typically after the tree has concluded its flowering.”
The clippings were taken by using garden shears to snip a small cluster of around four leaves from the top of the baby tree. Zettel then clipped the bottom three leaves off of the cluster, leaving a long stem and one leaf. She snipped that leaf in half — to reduce the leaf’s surface area and prevent water loss, she explained later in an email — and placed it vertically in a flat full of a special mixture of soilless media and perlite.
When Zettel and her colleagues collect clippings from Stumpy later this spring (which they’ll probably do about two or three times, she said), they’ll place multiple cuttings in each flat, until they run out of material. Then they’ll label each specimen and wait for the clippings to form roots.
“If we were collecting material like this from our grounds or from another location, we would be very careful in how we collect the material because we don’t want to harm the tree. We want to make proper pruning cuts, follow proper horticultural practice,” she said.
There’s not much material to take from Stumpy, but the fact that he’s set to get mulched comes with a silver lining for the arboretum scientists trying to propagate him.
“Because Stumpy is slated for removal, and because as you’ve seen, Stumpy is pretty … stumpy, and does not have a lot of growth of branches on it … we’ll probably collect as much material as we can,” Zettel said.
More material means more chances for Stumpy 2.0s to grow roots and take hold in those flats.
Nature is unpredictable. There’s no guarantee the Stumpy clippings will take root at all, in part because he’s already struggling. But the arboretum has a few tricks up its sleeves to give each Stumpy 2.0 the best chance.
The first is the propagation greenhouse, which allows horticulturists to control moisture levels, temperature and light to create ideal growing conditions.
Some of the clippings will also be shared with a satellite research station the arboretum has in McMinnville, Tennessee. The D.C. location will prepare each clipping before shipping them out of the DMV, and horticulturists in both locations will try to coax the clippings into new trees.
Different locations, and different clippings, mean many opportunities for success.
The cuttings should take between two and four weeks to root, but they’ll stay in the flats for around a year, Zettel said.
“Next spring we’ll pot them into individual pots and care for them in our production facility,” Zettel said. “As they grow, we’ll move them into bigger pots.”
It will take a few years for the baby Stumpies to grow big enough to be planted in the ground. And the arboretum wants to take extra care with the trees, to give them the best chance of survival.
“They’ll go back to the park service when we feel that they’re ready, when they’ve put on enough growth,” Zettel said. "When we feel that they’re strong enough. We also want to work with the park service, and to make sure that this all checks out with the time frame for the construction project. Because we don’t want to give them plants that they’re not ready to put in the ground