Is Pasta Water The Secret To Great Tomato Fertilizer? Here's The Truth

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If you're a regular in the kitchen, you likely already know that pasta water is akin to liquid gold thanks to all the starch it soaks up during the cooking process. However, you may be surprised to learn that some folks are adding this bonus ingredient to their garden instead of their marinara sauce. 

The theory is that the same nutrients that make the water tasty can also make it a great fertilizer, particularly for tomato plants. While it's true that there are some benefits of using pasta water in the garden, there are a few factors to consider before you bring it anywhere near your tomatoes.

It's vital to only give your tomatoes, or any other plant, unsalted pasta water. Otherwise, the salt can dry out the plant and kill it. Even if the plant survives, the salty water can cause an influx of sodium in the soil, which is also detrimental.

This is especially important to consider if you're planning on regularly donating your pasta water to your garden, since even a small amount of salt can build up in the dirt over time, effectively ruining it for tomatoes or anything else you wanted to plant. (See more beginner tomato growing tips for a successful first harvest).

For folks on a low-sodium diet, switching to unsalted pasta water may not pose much of an issue, especially if it leads to a flourishing garden. The truth is that there is some circumstantial evidence to support that pasta water can help tomatoes grow, so it may be worth keeping things unsalted in favor of free fertilizer. The key is the excess starch.

Different pasta types can contain nutrients like phosphorus and calcium, lending to the water's effectiveness as a fertilizer. The bad news, is that this also lends to the downside of using cooking water in the garden. Unfortunately, that nutrient-rich starch can also attract bacteria and pests. 

Small amounts of bacteria can be good for garden soil, but to avoid the potential for mold or insects, use pasta water in your garden sparingly. At the end of the day, pasta water isn't as effective as a commercial product like Miracle-Gro's water soluble tomato plant food, or even another DIY fertilizer made from kitchen scraps (i.e., onion peels).

With this said, if you don't feel like wasting gallons of water down the drain, it's fine to feed your tomatoes unsalted pasta water every now and then — so long as pasta night isn't a daily occurrence. Tomatoes and pasta may normally be a match made in heaven, but just not when it comes to the garden.