Use soil pH to choose a palette, not chase a perfect number

Take samples that represent the decision

Follow the sampling instructions of the chosen laboratory or kit. Keep visibly different beds or recently amended areas distinguishable instead of averaging the whole garden into a misleading result. Record where, when and how you sampled, and recent additions that could affect interpretation.

pH below 7 is acidic; above 7 is alkaline. It is not a nutrient analysis, contamination screen or drainage test. A low-cost home indication can guide a shortlist, while unexplained poor growth or a consequential amendment decision may justify laboratory advice.

Make three different planting decisions

Acidic, moist, draining shade: investigate the fern and foamflower scheme. Its source-backed conditions are a closer starting point than a chalk-loving dry border. Verify the precise plant and local winter suitability.

Neutral-to-alkaline, sunny, sharply draining soil: the lavender and sage example may fit. Reject it if moisture or shade conflicts, regardless of the pH result.

Strongly chalky ground: choose plants adapted to the actual alkaline soil. RHS notes that very chalky soil is not realistically acidified into an ericaceous bed. A separately managed container may accommodate a special plant, but it adds watering, suitable-media and repotting work.

A two-bed example avoids a needless treatment

Imagine a 4 × 2 m shaded bed with a recorded laboratory pH of 6.2 and a 6 × 2.5 m sunny, draining bed at 7.6. These are illustrative test results. Instead of trying to make both read 6.5, shortlist the moist-shade and dry-border palettes separately and check each source against the full site conditions.

The first bed is 8 m² and the second 15 m². Keep two entries in the brief, with separate soil, water and plant decisions. A single “garden pH” field can still contain both labelled observations; do not erase the difference.

If a future test conflicts with plant performance, check sampling, roots and water before applying amendments. Yellow leaves have several possible causes, and a visual symptom is not a chemical prescription.

Budget for the ongoing choice

Choosing a compatible palette usually avoids a recurring attempt to force the soil into another condition. A container alternative can be appropriate for one valued plant, but include suitable media, water quality where relevant, winter protection and the eventual adult pot in the decision.

Get professional soil advice before applying lime or acidifying products when the need and rate are uncertain. Keep the report and dates with the design. Recheck after a meaningful change or when advised, rather than treating every season as a reason to add something.