As with a lot of products, there is always some deceptive advertising.This couldn't be farther from the truth with rubber mulch or rubber pine straw based on several university studies. Like any product there is an entire list of all the potential benefits. However, several comprehensive reports going back many years have found just about every benefit at odds and in some cases completely contrary to both garden area uses and other general usage, i.e., ground coverage.
Why would someone even try rubber mulch?The main reason is the concern over termites from wood chips or other products harvested from the forest. The only other reason is to make use of all the recycled tires. Both of these can be dismissed without much thought. Termites are only a concern if the product is a wood chip grade and then only if used right on the border of your foundation of a traditional stick built structure. The rubber is never really recycled. It has just found another dumping ground -- your yard.
Now let's get to all those wonderful benefits this product promises.
First, the product is safe for flowers, plants and pets. Research from multiple universities has found that leaching from the recycled tires can kill entire aquatic wildlife, insects that are beneficial to plant growth, microbes that improve soil quality. It doesn't stop there. Any runoff finds its way to storm drainage areas or other water sources where it contaminates with chemicals that sound like they belong in a battery, e.g., cadmium, copper, sulfur, zinc. Most plants easily die from zinc toxicity.
The USDA has found after 20 years of research that based on the possible of zinc contamination, the product should never be used in gardens and landscaping.
Second, the product claims water and nutrients permeate. Yeah, this might happen for the first few weeks. However, earthworms and microbes require organic material as a food source. Without this, the entire structure of the soil pancakes preventing both water and air from entering. This results in conditions that breed both disease and kill off all the healthy bacteria, microbes and other organisms that facilitate the uptake of nutrients. Keep watering and now you have runoff.
Third, the material is supposed to be extremely durable, long lasting, no fading and doesn't decay. Well it does decay by harmful microbes resulting in the release of a toxic soup that then triggers another effect. The first wave of toxic chemicals prevents bacteria decay -- triggering a runaway effect of toxicity and overall death except from the bade microbes, fungi and bacteria you never want in your garden.
While there are multiple shades, the product is also going to fade. Most products unless specifically protected from harmful UV rays will fade. Another unwanted effect is the trapping of heat. As we know dark colored items, especially any black items, are going to absorb the heat from the daylight sun. The plants basically overheat and are starved of moisture. However, this is not directly related to the rubber mulch. This is just a natural process from anything close to black in color.
Before using this product, you should do some research yourself. You will find contradictive reporting, but both the US government studies and university reports tend to agree this product is not good or harmless to use. It may also depend on your intended use. If you have no concerns for the plant life, soil and any runoff issues, maybe this product can serve some purpose.