Using dolomite lime for marijuana cultivation can be beneficial when applied correctly, but it also has potential drawbacks. Here’s what you need to know:
Benefits of Dolomite Lime for Cannabis
1. pH Stabilization
– Dolomite lime (a mix of calcium carbonate and magnesium carbonate) helps buffer soil pH, keeping it in the optimal range (6.0–7.0 for soil).
– Prevents acidic fluctuations, which can lock out nutrients.
2. Calcium & Magnesium Supply
– Provides a slow-release source of calcium (Ca) and magnesium (Mg), essential for plant health.
– Helps prevent deficiencies like blossom end rot (calcium) or yellowing leaves (magnesium).
3. Improves Soil Structure
– Enhances microbial activity and nutrient availability in organic grows.
How to Use Dolomite Lime for Cannabis
– Pre-Planting (Soil Amendment)
– Mix 1–2 tablespoons per gallon of soil (or ~5–10 lbs per 100 sq ft) before planting.
– Works best when incorporated into the soil 2–4 weeks before use.
– Top-Dressing (Mid-Grow)
– Lightly sprinkle 1 tsp per gallon of soil and water in if deficiencies appear.
– Avoid overuse—it’s slow-acting and hard to flush out.
– Hydroponics/Coco Coir?
– Not recommended—use calmag supplements instead for better control.
Potential Drawbacks
– Can Raise pH Too Much – Overuse may make soil too alkaline (>7.0), causing nutrient lockout.
– Slow Release – Not ideal for quick fixes; use gypsum (for Ca) or Epsom salt (for Mg) if fast correction is needed.
– Not for All Mediums – Avoid in hydroponics or inert substrates like coco coir unless pH buffering is needed.
Alternatives to Dolomite Lime
– For calcium: Gypsum, oyster shell flour, or calmag supplements.
– For magnesium: Epsom salt (magnesium sulfate).
Final Tips
✔ Test soil pH before applying dolomite lime.
✔ Use sparingly—excess calcium can block potassium/iron uptake.
✔ Best suited for organic/living soil grows rather than synthetic nutrient setups.