How do I correct magnesium deficiency in plants?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.The process of addressing plants with magnesium deficiency begins with the capability to confirm the problem through quality testing. First, collect soil samples from several locations within your garden or landscape at a depth of 6 to 8 inches. You will submit these samples for lab analysis to determine the available magnesium in your soil. I always pair this with leaf tissue testing to give me the best and most accurate reading possible. If the reading is below 25 ppm in magnesium levels, action is to be taken.
Fast-Acting Solutions
- Apply Epsom salts as foliar spray for quick absorption
- Use 2% solution applied at dawn or dusk
- Shows visible improvement within 24-48 hours
- Best for emergency treatment in vegetable gardens
Soil Amendments
- Dolomitic lime raises pH while adding magnesium
- Apply before planting at 500-2000 lb/acre
- Takes 3-6 weeks to become fully available
- Ideal for acidic soils needing long-term correction
Specialized Blends
- Sulfate of potash magnesia for potassium-deficient soils
- Provides balanced K and Mg nutrition
- Apply at planting for season-long availability
- Prevents competitive inhibition between nutrients
The correct timing of applications will optimize the uptake of nutrients. Foliar sprays should always be applied in the early morning when the stomata are open, allowing for maximum absorption of the spray. Soil amendments should be worked into the soil before planting. In my experience, magnesium oxide is most effective when applied four weeks before planting for field crops. Be sure to water your plants thoroughly before any soil drench treatment.
After treatment, keep a close eye on the plant. You should see green, healthy new growth in just a few days if you use a foliar application. For soil corrections, the new leaves will show improvement. I take weekly measurements using a leaf chlorophyll meter to assess progress. Test the soil again after 6 weeks to confirm that the correction worked and the nutrient is available to the plant.
Prevent recurrence through balanced nutrition management. Manage calcium to magnesium ratios to be optimal between 3:1 and 5:1. Avoid high potassium fertilizers, as they restrict magnesium uptake. Conduct regular compliance soil testing on a seasonal basis to catch depletions early. You are so good at caring continuously, you should not get it again.
Read the full article: 7 Critical Signs of Magnesium Deficiency Plants
