Advice for planting an already-purchased Colorado Globe Blue Spruce in alkaline soil - Ask Extension
(Hello, I have also submitted a related question for our PJM Rhododendrons!). Our U of M Soil Test shows our soil is Ph 7.5.
We have already purchas...
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Advice for planting an already-purchased Colorado Globe Blue Spruce in alkaline soil #843220
Asked July 29, 2023, 4:37 PM EDT
(Hello, I have also submitted a related question for our PJM Rhododendrons!). Our U of M Soil Test shows our soil is Ph 7.5.
We have already purchased a Colorado Globe Blue Spruce and have dug out the hole. I'm reading that these shrubs prefer "slightly acidic" soil. U of M recommends amending with elemental sulfur, but of course it takes several months for the sulfur to react to the soil; I've read elsewhere that temps above 55 degrees are essential for that process. Question: should we amend with elemental sulfur now, and simply plant the shrub? Any other recommendations?
Ramsey County Minnesota
Expert Response
There are at least two problems that you will encounter with this planting.
1. Colorado blue spruce are not recommended for Minnesota because they tend to develop Rhizosphaera Needle cast disease and other diseases. Just so you are aware and know what to look for and how to treat see the website:
https://extension.umn.edu/plant-diseases/rhizosphaera-needle-cast
2. It’s difficult to change the pH quickly enough to benefit the Globe blue spruce. Planting the Globe in this soil violates the basic horticulture recommendation of “right plant in the right place.” It may survive but is unlikely to thrive.
Sorry to be the bearer of bad news but I would recommend that you return it and plant something else there. Evergreens that are more tolerant of high pH include: arborvitae, black hills spruce, mugo pine, ponderosa pine and junipers.
See:
https://extension.umn.edu/lawns-and-landscapes/landscape-design
1. Colorado blue spruce are not recommended for Minnesota because they tend to develop Rhizosphaera Needle cast disease and other diseases. Just so you are aware and know what to look for and how to treat see the website:
https://extension.umn.edu/plant-diseases/rhizosphaera-needle-cast
2. It’s difficult to change the pH quickly enough to benefit the Globe blue spruce. Planting the Globe in this soil violates the basic horticulture recommendation of “right plant in the right place.” It may survive but is unlikely to thrive.
Sorry to be the bearer of bad news but I would recommend that you return it and plant something else there. Evergreens that are more tolerant of high pH include: arborvitae, black hills spruce, mugo pine, ponderosa pine and junipers.
See:
https://extension.umn.edu/lawns-and-landscapes/landscape-design
