Soil pH controls which nutrients plants can actually absorb from the soil. Get it wrong and even rich, fertilized soil leaves plants starving.
What pH means
pH is a 0–14 scale: 7 is neutral, below 7 is acidic, above 7 is alkaline. Most vegetables prefer 6.0–7.0 — slightly acidic. Below 5.5 or above 7.5, key nutrients become locked up and unavailable.
Crops with strong preferences
- Acid lovers (5.0–6.0): blueberries, azaleas, rhododendrons, potatoes
- Neutral (6.5–7.0): most vegetables, herbs, lawns
- Alkaline-tolerant (7.0–7.5): asparagus, beets, brassicas, lavender
How to test
A $15 home test kit is accurate enough for most decisions. For a serious diagnosis, send a sample to your local agricultural extension — about $20, gives you pH plus full nutrient profile.
Fixing pH
- Too acidic (low): add garden lime. ~5 lbs per 100 sq ft shifts by 1 point. Slow — takes 3–6 months.
- Too alkaline (high): add elemental sulfur or peat moss. Even slower than lime.
- Maintenance: heavy compost amendments naturally drift toward neutral.
Never dump vinegar or baking soda on soil — both create salt buildup that damages roots.