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Milk and Tomato Growing

Tomatoes and milk1

You may have heard or read that milk is sometimes used to help grow tomatoes–and also squash.

Is it a fertilizer?

Milk contains calcium (Ca). Calcium is an important plant macronutrient. Macronutrients are foods that help plants grow and function. Calcium helps build plant cell walls which in turn allow the transport of other plant nutrients. Also calcium level in the soil controls the soil pH (pH is a chemical balance that allows plants to operate, or not). If calcium is washed out of the soil, the soil will become more acid and can affect plant growth. (Agricultural lime such as dolomite lime contains calcium.)

If you feed plants milk–whole milk or powdered milk–you are feeding plants calcium.

So milk can be a tomato plant fertilizer: Sprinkle a quarter to a half cup of powdered milk on top of the soil after planting, and repeat every two weeks throughout the growing season.

What else does milk do for plants?

Milk is a fungicide.

Old-time garden wisdom AND recent scientific plant research say that milk contains fungicidal properties. If you spray milk on plants, it will control the growth of bad fungi.

Fungi are microscopic organisms. A handful of soil contains thousands and thousands and thousands of fungi. There are good fungi and bad fungi. Good fungi help build the soil by breaking down organic matter into nutrients plants can use. Bad fungi are parasites that feed on plants. Bad fungi include mildews (downy mildew, powdery mildew), rusts, rots (root rot, damping off, fruit rot), canker, scab, spot (black spot and anthracnose), wilts (fusarium and verticillium) and smuts (and black sooty molds caused by black sooty fungi spores).

Fungi are spread by spores. They germinate and root much like plants. When a fungi takes root as a parasite on plant tissue it feeds and begins to grow. A fungus can be prevented from rooting and can be removed (prune off the infected plant tissue and throw it away in a paper bag so that the fungi spores do not spread). Fungi allowed to grow will spread via spores floating on the wind or swept along in a drop of water.

Fungicides rarely kill fungi. They are most useful as a preventive, not as a cure. Fungicides cover plant tissue and do not allow fungi to root.

Plant researches in Brazil and Australia have recently used milk as a fungicide on vegetable crops, grapes, and flower crops. They found that spraying a dilute mix of 1 part milk and 9 parts water prevented fungi from growing. (The researchers also believe that the potassium phosphate in milk helps boost the plant’s immune system and may also work as an antibiotic.)

Once again, milk–like other fungicides–does not cure fungal diseases but helps to prevent them. Milk keeps fungi from growing and spreading.

A note: skim-fat milk works best; the fat in whole milk may clog up your sprayer. As well, reconstituted powdered milk will work.

Tomato disease fighter formula: combine 1 part skim milk and 9 parts water. Spray the plant every two to three weeks until mid-summer (most fungal diseases have run their course by mid-summer, except where the weather stays warm and humid).

 

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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      • When I plant my tomatoes I make a mixture of powdered milk, 100% instant tea, crushed egg shells and epsom salt and put in every hole before the plant.

  1. I have one tomato plant in container. Larger tomatoes have blossom end rot. With the milk, do I put it in soil with water or spray on leaves and tomatoes?

    • You can remove the fruit with blossom end rot; it is not uncommon for early developing fruit to develop blossom end rot. And you can spray the plant with a milk spray and feed it with a fertilizer that has magnesium and calcium added such as Lily Miller Mor-Crop. The fruit that follows should be fine; be sure to keep the soil just moist–not too wet, never dry.

  2. Also my powdered milk i happened to have on hand says on he label.. cholesterol 4 mg, sodium 126 mg, Sugar’s 12 G protein 8G vitamin A 11% vitamin C 2% calcium 28% and vitamin D 25% so my question is is this powdered milk even has have enough calcium in it along with other things would it be safe to use

    • Your powdered milk should be safe to use. If you have doubts, try the solution on one or two plants, not the entire crop,

  3. How often do I use the powered milk water treatment. I was told I could crush up one antacid to one gallon water stir well and water 2 cups per 5 gallon. Container tomatoes. I watered them with that once. Either with that mixture or powdered milk to water mixture how often would I water my container tomatoes( that already have blossom end rot) with the milk mixture.

    • One dose of powdered milk should be sufficient. Blossom end rot is temperature related. As the soil temperature warms, plants will be able to draw up calcium from the soil. Chilly soil temperatures lock-up calcium in the soil; when the soil warms the chemical process to draw up calcium is initiated.

  4. What is the ratio of powdered milk to
    water? Also, if you have any other suggestions, I would greatly appreciate it!! My tomatoes have blossom end rot.
    Thank you in advance!

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