That tub of yogurt in the back of your fridge can get a second life in your garden, according to a surprising tip doing the rounds on the internet. Yogurt contains calcium and protein, which are two important nutrients that tomatoes need to thrive. Although whether a tomato plant can use any of them is a separate question.
The claim that a spoonful of yogurt added to your watering can can stimulate tomato growth comes up regularly on gardening forums, usually touted as a good source of calcium for tomatoes. Logic says that dairy is rich in calcium – and tomatoes often suffer from calcium problems – so we give the plants a dose dairy fertilizer can provide plants with what they need. But this theory is not exactly accurate.
But yogurt isn’t exactly useless in the garden. Use it together with an appropriate tomato fertilizer and could possibly give the plants a little extra boost. I’ll walk you through the truth behind the claim that yogurt is a good fertilizer for tomatoes, how to try it yourself, and some precautions to take before using yogurt in your garden.
Why gardeners use yogurt on tomato plants
Calcium is the main claim behind using yogurt as a tomato fertilizer. Flower rot end it ruins fruit every summer, and a lack of calcium is often cited as the culprit, so a tub of yogurt in the fridge is probably the closest source. Plain yogurt carries enough calcium by food standards, which makes the connection seem obvious.
However, the rest of the appeal spreads wider than this one mineral. Yogurt is also a good source of protein and protein nitrogen for plants.
Lactose is a sugar that soil microbes it will eat easily, which can improve the soil. Then there are the live cultures in yogurt, mostly Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophiluswhich also fit into the popular concept of nutrient soil biology. The tub headed for the tub regardless.
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Does Yogurt Tomato Fertilizer Really Work?
The case for yogurt as a source of calcium for tomatoes it falls apart once you actually look at the numbers. A tablespoon (15 ml) of yogurt carries about 20 milligrams of calcium. A fully fruited tomato moves much more than that throughout a season, and the soil it’s growing in almost certainly already has a surplus. So a spoonful of yogurt fertilizer does not have much impact.
However, arithmetic is not the real problem. Calcium in dairy arrives bound to casein, which means soil microbes must break it down before roots can get to useful nutrients. Warmth and time do this work on their own schedule. No one decides when the nutrient will appear or if it does so while the plant still needs it.
Blossom end rot is rarely the result of calcium deficiency in the first place. It is more often a delivery failure. Unequal watering tomato plants interrupts the movement of calcium in fruit development, creating blossom end rot. Yogurt does not address the calcium blocking mechanism, it only addresses the nutrient itself.
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Best type of yogurt to use
If you still want to try it homemade tomato fertilizer Anyway, choosing the right yogurt is key. Plain yogurt is the only version that belongs anywhere near a garden bed. Nothing else in the dairy aisle qualifies. A tub of yogurt is cheap, and the low-fat option leaves less of a greasy residue behind than full-fat. Fruit, honey, added sugar – none of it should reach the garden.
Artificial sweeteners are the other thing to skip as they don’t add anything to the soil and no one can say how residues behave in a garden bed. Yogurt with sugar causes a faster problem, the design ants, waspsand rodents at the base of the plant. Scented tubs also carry stabilizers that no one should throw into the garden.
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How to make yogurt tomato compost
Dilution does the safe work for tomato yogurt fertilizer. One tablespoon (15 ml) of plain yogurt mixed into a full 2 gallon (9 L) watering can is the strongest dose to use. Mix it well so nothing settles in lumps, then pour slowly around the drip line of your tomatoes, about 6 to 8 inches (15-20 cm) from the stem.
Follow with a can of plain water to get the yogurt fertilizer below the soil surface, as dairy left on top can cause problems. Keep every drop off the foliage as well. Wet residue on leaves in hot weather causes fungus tomato diseases much more difficult to correct than any nutrient deficiency.
How often to apply
Applying tomato yogurt fertilizer once a month during the growing season is enough, and often less is good. This belongs in small experiments rather than planned feeding, so there isn’t much benefit in building a routine around it.
Anyone who is curious can run it right. Treat one plant with the diluted mixture, leave a matching untreated plant next to it and compare at the end of the season. This beats the internet jokes and costs a tub of yogurt.
What you should never do is replace a scheduled feed of traditional tomato fertilizer with just yogurt. A plant that receives no real fertilizer and only yogurt is simply not being fed properly.
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Mistakes to avoid
Going to a dose of undiluted yogurt fertilizer is big problem for tomato plants. A drop of dairy in warm soil turns sour and attracts flies. It can also thicken into a crust that sheds water instead of letting it through. Container plants suffer worse, as a pot contains little soil and none of the microbial diversity that a bed uses to process organic matter.
Conversely, if the goal is to feed the soil, a bag of Back to Roots Organic Compost from Home Depot it does this job right.
Repeated applications of tomato yogurt fertilizer are the other pitfall. Residue builds up and a spot that has been treated over and over again starts to smell bad and stays wet.
Signs to stop using yogurt
A sour smell around the base of the plant means the residue is fermenting rather than breaking down cleanly. White or indistinct growth throughout the soil surface marks the same subject. Scrape off what you can and rinse the area with clean water.
Insects and animals can also cause problems. Fungus gnats drifting around the stem are a sign that something is wrong, but more so are fruit flies. The soil was turned over at night raccoon or rats is the surest sign, since something has found the smell interesting. And a plant that looks worse than before the experiment began has already answered the question.
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What to use instead
Fruiting tomatoes need constant nitrogen, phosphorus and potassiumwith emphasis on the latter two once flowering begins. Plants also need calcium and magnesium in amounts that kitchen scraps don’t. Espoma Tomato-tone 3-4-6 with 8% calcium from Amazon it covers all the needs of a tomato in one product and yogurt just can’t compete.
Watering does more to rot the flowers than any additive from your fridge. Deep, even soaks at a steady rate with a few inches of mulch to hold in moisture keep calcium moving through the fruit. Overall, save the yogurt for your breakfast. Invest in a good organic commercial tomato fertilizer or homemade compost anti.
