A laboratory soil test is the best way to accurately measure acidity (plus nutrient content and organic matter content), to determine if any adjustments are needed. Amending soil with a top-dressing of compost is usually helpful to most plants, but it won't remedy a pH issue if one exists. Conifer needles do not acidify the soil to any measurable degree, so there is likely another issue if plants in that area are struggling. We've been in a significant drought for much of the past two years; were any of the struggling plants watered periodically to alleviate stress from drying roots? Are they shade-tolerant species, where shading from the spruce would not be a problem? It's hard to guess as to the cause without knowing which plant species are struggling and seeing a photo of the site conditions or plant symptoms.

The same thing is recommended for the climbing roses and clematis; please share photos of their symptoms, and can you tell us when they started (only this spring, or was it also present last year)? Did anything change in their growing conditions, and were they fertilized in the past year? (If so, what was applied and what time of year?) Could anything have kept their roots wetter than usual, or was any type of herbicide used near the plants this spring?

Miri