Boston Fern with Magnesium Deficiency? Rare but Treatable
Nephrolepis exaltata
Magnesium deficiency is a nutrient disorder characterized by interveinal chlorosis, where leaf tissue between veins turns yellow while the veins remain green. This deficiency affects older leaves first as magnesium is a mobile nutrient that plants relocate to support new growth. Magnesium is essential for chlorophyll production and photosynthesis, making this deficiency critical for plant health.
ð Symptoms
- âĒ Interveinal chlorosis with yellowing between leaf veins while veins stay green
- âĒ Symptoms appear first on older, lower leaves
- âĒ Brown or rusty-brown spots as deficiency worsens
- âĒ Reddish-purple discoloration on leaf edges and tips
- âĒ Necrotic spots in severe cases
- âĒ Stunted growth and reduced plant vigor
- âĒ Poor fruit development and reduced yield
â Possible Causes
- â Sandy soils with low cation exchange capacity
- â Excessive rainfall or irrigation washing out magnesium ions
- â Acidic soils with pH below 6.0
- â High levels of competing cations (potassium, calcium, ammonium)
- â Over-application of potassium fertilizers
- â Cold soil temperatures reducing nutrient uptake
- â Poor root development limiting nutrient absorption
ð Treatment
Quick Fixes
Step 1
Mix 1 tablespoon Epsom salt per gallon of water for emergency foliar application
Step 2
Spray affected leaves immediately in early morning or late evening
Step 3
Focus on yellowing areas between leaf veins
Step 4
Reapply every 7 days until symptoms reduce
Step 5
Follow with liquid magnesium fertilizer (amino acid chelated) at manufacturer recommended rates
Organic Treatment
Step 1
Dissolve 1 tablespoon of Epsom salt (magnesium sulfate) per gallon of water
Step 2
Apply as foliar spray in early morning or late afternoon
Step 3
Spray leaves thoroughly, ensuring coverage of both upper and lower surfaces
Step 4
Repeat application every 15 days for 4 total applications
Step 5
Add aged compost or well-rotted manure to soil to provide long-term magnesium
ðĄïļ Prevention
- â Maintain soil pH between 6.0 and 7.0 for optimal magnesium availability
- â Apply compost mulch to prevent nutrient leaching during heavy rain
- â Test soil regularly to monitor magnesium levels
- â Use balanced fertilizers to avoid excess potassium or calcium
- â Incorporate organic matter annually to improve soil structure
- â Avoid overwatering which can leach magnesium from soil
ðą Care Guide: Boston Fern
ð§ How to Water
Water when the top inch of soil feels dry, usually 2-3 times per week. Keep soil consistently moist but never soggy. Reduce watering in winter when growth slows. Use room temperature water to avoid shocking the roots.
âïļ Lighting
Prefers bright, indirect light but can tolerate low light conditions. Avoid direct sunlight which can scorch the delicate fronds. East-facing windows or filtered light from south/west windows work best. Insufficient light may cause yellowing leaves.
ðŠī Ideal Soil
Use well-draining, rich organic soil with a pH of 5.5-6.5. A peat-based potting mix with added perlite works well. The soil should retain moisture while allowing excess water to drain freely.