About this time last year I posted photos of the installation of my new pollinator gardens (all perennials). As you can tell from the photos below, all of these plants have not only survived but thrived with their midsummer rootwashing.
The only ones that didn’t make it were the six Lavandula stoechas ‘Bandera Purple’ (see above). They did fine through the summer and well into winter. But with our surprise snowstorm in February (along with a 20-degree temperature drop in one night – from 33 to 14F), all but one of these marginally hardy plants (USDA zones 7-10) gave up the ghost. I won’t make that mistake again. But I will continue to root wash ALL of my perennials before I plant.
And since it’s Independence Day here in the US, I thought I’d continue with the “free your roots” theme and discuss the medieval torture system that passes for recommended B&B tree installation practices. I’m talking about the burlap, the twine, and the wire baskets that are left on the root ball and cunningly hidden underground to do their damage over the years.
There is a great deal of disagreement about what to do with all the foreign material that’s used to keep tree root balls intact during shipment. To be clear, that is the ONLY thing they are intended to do. There is no research that shows leaving them on benefits the tree at all. The reason they are left on is because it’s more economically feasible for the installation company to do it this way. Personally I think that’s a pretty crappy reason, particularly when you are looking at trees that can cost hundreds or thousands of dollars.
Most studies that have addressed the issue have been short term: two or three years, rarely longer. Irreversible damage to roots can take years to develop. It’s useful, therefore, to look at the landscape evidence to see what happens with all these barriers to root growth and establishment.
Arborist and landscape designer Lyle Collins recently excavated the remains of trees that had been installed in 1991. The trees had died years ago and certainly hadn’t grown much as evidenced by their trunk size.
But while the trees didn’t survive, the burlap, wire basket, and webbing were all still there almost 30 years later.
The clay rootballs are nearly intact as well. That’s not what you want to see. Roots must establish outside the rootball into the native soil, or they won’t survive.
Eventually I’m convinced long-term research will show the folly of leaving foreign materials on the rootballs of B&B trees. In the meantime, I’ll continue to plant trees in a way that ensures their roots are in contact with the native soil and free from any unnatural barriers to growth.