Can milk provide calcium for tomato plants?
Written by
Benjamin Miller
Reviewed by
Prof. Martin Thorne, Ph.D.Milk has negligible amounts of calcium that are useful for tomato plants, even when milk contains calcium. The large organic molecules in the milk do not get efficiently absorbed through the roots, which means that plants utilize less than 2% of the available calcium. Year after year, I have tried milk treatments with unsatisfactory results.
Absorption Issues
- Casein proteins bind calcium making it biologically unavailable for plants
- Fat content creates hydrophobic barriers blocking root membrane transfer
- Lactose sugars feed harmful microbes instead of nourishing plants
Pest Attraction
- Sour milk odors draw rodents, raccoons and insect pests overnight
- Bacterial growth creates slimy residues promoting fungal diseases
- Ant infestations increase around treated plants within 48 hours
Soil Damage
- pH imbalance occurs as milk ferments creating acidic conditions
- Surface crusting prevents water penetration and oxygen exchange
- Nutrient lockup happens when milk proteins bind essential minerals
Select effective alternatives such as gypsum or calcium nitrate, which are soluble sources of instant calcium, with no downsides. I apply gypsum at planting and calcium nitrate during fruiting for ongoing protection against blossom end rot.
Use appropriate rates for results. Before transplanting, ensure that you use 1 cup of gypsum for each plant, working it into the topsoil. For existing plants, use 4 tablespoons of calcium nitrate per gallon of water and water them once a week. Always water thoroughly after applying calcium nitrate.
Combine calcium with moisture management, as calcium travels with water through plants, making irrigation a crucial aspect of plant care. Install drip systems to deliver water uniformly and efficiently. During hot temperature regimes, inspect soil moisture levels daily. You'll find that the pairing will prevent blossom end rot like nothing else.
Check plants weekly after treatment. Look for vigorous new growth without leaf curling. The fruit should be growing evenly without leathery patches. Ensure that applications are adjusted based on the plant's response and prevailing weather conditions for optimal results.
Read the full article: Tomato Blossom End Rot Explained Simply
