Raising soil pH means making acidic soil less acidic. The standard amendment is agricultural lime, but the rate depends on soil test results, target crop, soil texture, and lime quality. Guessing is risky because overliming can lock up nutrients and is hard to reverse.
If your soil pH is already in range, do not add lime just because it is traditional garden advice.
For lowering pH, read How to Lower Soil pH Naturally.
Last updated: June 6, 2026.
Quick Answer
Raise soil pH by getting a soil test, applying the recommended amount of agricultural lime, and giving it months to react. Use calcitic lime when you need calcium without magnesium, and dolomitic lime when magnesium is also low. Avoid casual wood ash or repeated lime without testing.
When Soil pH Is Too Low
Acidic soil can reduce nutrient availability and increase aluminum or manganese issues in some soils. Many vegetables prefer slightly acidic to near-neutral soil, but the target depends on crop.
A soil test should guide:
- whether lime is needed
- how much to apply
- what crop target pH to use
- whether magnesium is low
Lime Types
| Lime type | Contains | Best use |
|---|---|---|
| calcitic lime | calcium carbonate | low pH, magnesium adequate |
| dolomitic lime | calcium and magnesium carbonates | low pH plus low magnesium |
| pelletized lime | lime in pellet form | easier spreading |
| hydrated lime | fast acting | riskier, not usually best for home gardens |
Pelletized lime is easier to handle, but the soil chemistry depends on the lime material and fineness.
How to Apply Lime
- Test soil.
- Choose the crop on the submission form.
- Read the lime recommendation.
- Measure garden area.
- Apply the correct amount.
- Mix into the top 6 to 8 inches before planting when possible.
- Water normally.
- Retest later rather than reapplying blindly.
Fall application is often useful because lime has time to react before spring planting.
Wood Ash Caution
Wood ash can raise pH and add potassium, but it is easy to overuse. Do not use wood ash if:
- soil pH is already high
- potassium is high
- you garden near acid-loving plants
- ash contains trash, treated wood, or contaminants
- you cannot apply it evenly
Wood ash is not a substitute for a soil-test-based lime recommendation.
Overliming Problems
Too much lime can:
- raise pH too high
- reduce iron availability
- reduce manganese availability
- cause yellowing in sensitive plants
- interfere with nutrient balance
- make acid-loving crops fail
It is much easier to add lime later than to remove it.
Containers and Raised Beds
Potting mixes may already contain limestone to adjust pH. Do not add garden lime to containers unless you know the mix pH and plant need.
For raised beds, test the mix after it settles, especially if it contains compost, mushroom compost, or manure.
FAQ
How long does lime take to raise pH?
It can take months, depending on lime fineness, soil moisture, mixing, and soil type.
Can baking soda raise soil pH?
Do not use baking soda as a garden pH correction. Use soil-test-based lime recommendations instead.
Should I use dolomitic lime for tomatoes?
Only if pH is low and magnesium is also needed. If magnesium is adequate, calcitic lime may be better.
Related Reading
- How to Read a Soil Test Report
- Why Tomato Plants Need Calcium
- Mushroom Compost Pros and Cons
- Best Soil for Raised Garden Beds