After its introduction to the eastern United States in the 1950s, the invasive insect Hemlock Wooly Adelgid (HWA; Adelges tsugae) has devastated eastern hemlock (Tsuga canadensis) populations. This sap-feeding insect has no natural predators in the Eastern US, allowing it to consume hemlock leaves uncontrollably, killing the tree. Like 80% of plant species, hemlocks form an obligate symbiosis with (ecto)mycorrhizal fungi, a type of fungus that forages for nitrogen (N) and phosphorous (P), which it provides to the tree in exchange for carbon compounds. The tree cannot survive without these fungi, as mycorrhizae’s fine hyphal networks access nutrient pools much more effectively than tree roots can, and the fungi cannot survive without the tree’s supply of carbon compounds. Previous studies have shown that ectomycorrhizal abundance in eastern hemlocks is strongly correlated to severity of HWA infestation, with infested trees having significantly less fungal biomass associated with their roots than healthy trees. At Harvard Forest, hemlock trees have been infested with HWA since the early 2000’s, but some are doing better than others. The cause of this differential response is unknown. Could soil biogeochemistry and/or mycorrhizal productivity account for these differences in hemlock health? Here, we used soil analyses, mycorrhizal ingrowth bags, and root exudates to test for differences in subterranean factors between healthy and unhealthy hemlock sites. We found differences in soil pH between the sites, but no mycorrhizae were collected from either site, as in-growth bags were not left underground long enough for significant amounts of hyphae to colonize them. Learning from this, we provide more specific recommendations for how fungal in-growth bags might be deployed more successfully in future studies. This study identifies promising areas of further research at the intersection of invasive ecology and plant-soil feedbacks and details specific ways to continue researching the potential subterranean mechanisms of hemlock resistance to HWA.