Why Do Gardeners Put A Bar Of Soap Near Tomato Plants — And Should You Try It?

We may receive a commission on purchases made from links.

Growing tomatoes in the garden is a favorite endeavor that most people look forward to once spring comes around. Although they take a little bit of work to nurture, harvesting those delicious, ripe fruits to throw into salads or slice onto sandwiches is a welcome reward for the extra toil. However, it can be distressing when garden visitors such as deer, rabbits, and birds come to enjoy the fruits as much as you do. That's one of the reasons you should put a bar of soap in your yard and why many gardeners hang soap near their tomato plants. But not just any soap. It has to be one that has a strong fragrance, like Irish Spring deodorant bar soap (available at Amazon), for example.

It's believed that browsing animals, like deer, are repelled by certain strong fragrances like peppermint, cinnamon, lemongrass, garlic, and cloves. So, placing strongly scented bars of soap near the plants that you want to protect from browsing does seem to make sense. A research study conducted by the University of Nebraska in 1991 found that using bars of soap did provide a level of protection to crops that were frequently browsed, and this is backed up by the University of Connecticut's School of Agriculture, Health, and Natural Resources. However, it may be a short-lived exercise, as the fragrance starts to dissipate and the animals become accustomed to the scent. This means that there's no harm in trying this practice, but it shouldn't be your only defense to keep your tomatoes safe. You'll also find that what works for one person may not work in your garden, so you may want to include other natural ingredients that can repel deer from your yard.

There are a couple of ways that you can hang a bar of strongly-scented soap near your tomato plants. You can simply drill a hole in the soap, thread some string or a long twist tie through it, and then suspend it from the trellis. Try to ensure that melted soap won't end up on your plants when it rains. If your chosen soap, which should be tallow-based, is individually wrapped, make sure to leave the wrapper on it before hanging. You should find that one bar of soap will protect plants in a 1-yard radius. Alternatively, you could put the soap in a fine-mesh bag and use that to hang it.

When using this type of preventative measure around your tomatoes, bear in mind that soaps may harm your plants if used incorrectly. That's one of the reasons you want to think twice before adding soap to your weed killer. For example, if the soap you use contains sodium hydroxide (a modern lye), this may damage plant tissues and cause things like leaf burn. So, heed the warning about ensuring that none of the soap is able to drip onto your tomato plants. You'll also find that excessive amounts of sodium in the soil can be damaging to plants. This means that you really don't want the bars of soap to dissolve completely and end up in the ground in a concentrated area. So, once the fragrance has dissipated some, make sure you remove the soap from the garden and replace it with a fresh one.