What soil pH is best for kale?
Written by
Tina Carter
Reviewed by
Prof. Martin Thorne, Ph.D.Soil pH for kale establishes the nutritional availability and resistance to diseases. The target pH ranges from 6.0 to 7.0, which is considered from slightly acidic to neutral. I test my garden beds annually with a $15 probe. Last season, increasing my pH from 5.3 to 6.5 tripled my yields by improving nitrogen uptake.
Testing Methods
- Digital meters provide instant readings (calibrate monthly)
- Chemical test kits measure acidity/alkalinity in 10 minutes
- Lab tests via local extension offices offer detailed reports
Amending Strategies
- Add agricultural lime (2 lbs/10 sq ft) if pH <6.0
- Mix elemental sulfur (1 lb/10 sq ft) if pH >7.0
- Retest soil 4 weeks after amendments
Disease Prevention
- Clubroot fungus thrives below pH 6.0
- Rotate crops every 3 years
- Sterilize tools after infected soil contact
Organic materials are critical for buffering pH shifts. For example, my clay soil was at 5.8 last year and I mixed in 3 inches of compost to boost it to 6.4 on its own. Coffee grounds are acidic and wood ash is alkaline, both provide quick solutions but excessive use can create imbalances. Measure twice, amend once.
pH dramatically affects nutrient availability. For example, at 6.5 kale will take up 90% of phosphorus in the soil, but below pH 6.0 manganese will start to cause leaf curling due to phytotoxicity. This can be ameliorated by adding lime to increase the pH of the soil, and in three weeks I started to see new growth without leaf curl. Always make sure to double-check the pH with visible deficiency symptoms.
To perform rapid DIY tests, you can mix the soil you wish to test with distilled water and either baking soda (fizzes if acidic) or vinegar (fizzes if alkaline). This may not be as accurate or precise as a meter, but I used a similar method to identify urgent pH issues during a very rainy season when my probes had failed.
Read the full article: How to Grow Kale: Complete Planting and Harvesting Guide
