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Is Miracle-Gro Toxic or Safe for Frogs? 

I love amphibians, especially frogs. I’ve worked in pet stores finding frogs new homes with the proper care and setups. And right now I work as a zookeeper and at an exotic veterinary clinic. I’ve even had a pac-man frog as a pet!

We want to make sure anyone who has a pet frog is using proper husbandry so they have a happy, healthy, frog friend. In my jobs I have often been asked about using Miracle-Gro for pet frogs and always have the same answer.

It is not recommended to use Miracle-Gro products in a terrarium for amphibian or reptile species. Miracle-Gro has not tested their products for use with pet species and cannot suggest using their product in substrate without speaking with an exotic veterinarian about other options first. 

In this article we will talk about Miracle-Gro products as substrates for amphibian pets kept indoors. We will also talk about using them outside for landscaping or gardens where frog species may reside naturally.

We’ll talk about the best alternative options for your indoor frog pets and how to do your part keeping every frog, inside or outside, as healthy as they can be! 

Miracle-Gro is not a Suitable Substrate For Pet Frogs

Since there is a lot of debate about this topic in the herping community, I reached out to a customer service representative for Miracle-Gro in November 2022 and asked them directly if their products were safe to use in frog terrariums.

Laurie, a customer support rep from Miracle-Gro, responded to me, saying “Unfortunately, we would not be able to recommend a product for your frog terrarium. Our products have not been tested for use in that type of environment.”

Wood Frog in a vivarium with substrate

This is not necessarily saying their products are not safe, but that it is not meant for use in terrariums with live animals.  

The Miracle-Gro website does have suggestions for using their products in terrariums with live plant species. It is possible to create a space with proper drainage and lighting for indoor use.

However, not suggested when used in conjecture with live animals.

Amphibians breathe through their skin and need substrate that will not harm their mucous membranes when burrowed in it.

There is also always the concern for accidental ingestion of the substrate as well. 

Pet frogs enjoy burrowing  and require a humid and moist environment to keep the mucous membranes of their skin healthy for respiration. Having a frog or a toad as a pet will mean creating a moist, but not wet, house for them to dig and live in.

Miracle-Gro may be a less expensive, more easily attainable substrate, but should not be considered as an option. 

The toxicity level of Miracle-Gro with frogs is not something that is measured in any studies right now. So, not too much is known about how much it really affects frogs and amphibians.

We can really only go based on its intended purpose, promoting plant growth, and the ingredients in most Miracle-Gro products. 

What Substrate Can be Used for Pet Frogs? 

Substrate is a layer of bedding used for a pets enclosure and is usually species-specific. It is meant to help their houses mimic a natural environment that meets their temperature and humidity needs and is easy to clean and replace.

So, what are some good substrates for amphibians?

Reptile supply companies like Zilla, Exo-Terra, and Zoo Med create everything you would need for housing a pet frog, including appropriate substrate.

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I personally use a mixture of Eco-Earth and coconut husk for my reptiles at home and find this mixture holds humidity and lets them dig around for fun! Jungle mixes and mosses are the most appropriate substrates for amphibian species as they hold moisture and humidity and allow them to burrow into. 

Sphagnum moss is the most commonly used moss among reptile and amphibian pet parents and zookeepers. Moss should always be damp to allow for higher humidity, but should never be soaking wet. Moss can be clumped together or mixed in with the first substrate to be distributed throughout the enclosure. 

Dirt and substrates should not be soaking wet when housed with amphibian species. Too wet conditions can cause mold to grow. Installing a drainage system to carry the excess water out of the enclosure is an option and is highly recommended with bioactive enclosures. If your enclosure isn’t bioactive, a daily misting to keep the substrate moist is the best thing to do for your frog. 

Desert blends, carpet liners, sand, and aspen blends are not appropriate for amphibian species as they do not meet proper environment requirements.

Carpets do not allow for digging or hiding, desert blends are typically made from crushed walnut shells that are not well suited for amphibians. Aspen blends and other bark substrates could cause harm to the frog’s skin and disrupt respiration. 

Are Fertilizers Bad for Outdoor Frogs? 

Some of our frog friends live outside by our gardens or water features.

You can use fertilizers in your garden or yard even if you would like to attract or keep wild frogs behind your home. However, avoid synthetic fertilizers, high concentrations, and locations that could run off into waterways.

Miracle-Gro has many organic ingredients, including sphagnum peat moss, bark, and coconut husk. It also contains compost, a wetting agent, and fertilizer. Their fertilizer is made up of nitrogen and phosphate in small percentages. These ingredients can be found on their website for each product they offer and are listed on their labels in-store. 

Frogs and fish in the wild are highly susceptible to fertilizers and compost from farm and home runoff that wash into waterways. Large manure loads from farms contribute to run-off and water contamination. 

Fertilizers and contaminants high in nitrate, which is nitrogen with oxygen, can be absorbed through amphibian skin.

Even low levels of nitrate have been found to be fatal to frogs.

Excess nitrogen in waterways depletes oxygen in the water. Depleted oxygen can cause skeletal deformities in developing eggs, which in turn reduces aquatic and semi-aquatic species diversity. 

Usually, fertilizers have to be present in high concentrations to cause a problem. To be safe, use fertilizers in small amounts and keep gardens or flowerbeds a distance away from sources of water. Streams flowing through our backyards can be home to dozens of aquatic species and may deposit into larger waterways, carrying the contaminants with them. 

Find out what substrates you should use for your pet frog in my article here.

This article was written by Melissa M. who holds a Bachelors of Science in Fisheries and Wildlife Sciences, and a Master Herpetologist certificate. The article was edited and published by Daniella, Master Herpetologist in the author profile below.


Garden right with Miracle-gro. Garden Right with MiracleGro. (n.d.). Retrieved from https://www.miraclegro.com/en-us 

U.S. Fish & Wildlife Service Homeowner’s Guide to protecting frogs … (n.d.). Retrieved from https://dwr.virginia.gov/wp-content/uploads/homeowners-guide-frogs.pdf Boehm, R. (2020, June 1). Jstor Home. Reviving the Dead Zone: Solutions to Benefit Both Gulf Coast Fishers and Midwest Farmers. Retrieved from https://www.jstor.org/

Daniella Master Herpetologist

Daniella is a Master Herpetologist and the founder of toadsnfrogs.com, a website dedicated to educating the general population on frogs by meeting them where they are in their online Google Search. Daniella is passionate about frogs and put her digital marketing skills and teaching experience to good use by creating these helpful resources to encourage better education, understanding, and care for frogs.