A peek into the research & design behind Rosy Soil

A peek into the research & design behind Rosy Soil

Hey y’all. I’m Jules, a soil researcher with a passion for unraveling the mysteries of the soil via experimentation and study. My journey into agriculture began as an urban farmer & garden educator driven by a passion to bring kids into the garden. Over the years, my hands-on experience cultivating crops and nurturing soil health sparked my curiosity on a deeper level. As a dedicated soil researcher now, I blend practical insight from the field with scientific inquiry to study and formulate aspirational and sustainable potting soil mixes. At Rosy Soil, I delve into the fascinating and frankly mystifying world of soil with a specific focus on biochar. In this report, I’ll include some of the insights that I’ve gained about soil and biochar, its importance for sustainable agriculture and the innovative techniques I’m using to study it.  

As a company that is committed to plant and planet health, our approach to formulating soil is a bit different than what you would typically expect. At Rosy, we’ve made a commitment to design soils with the highest quality organic inputs that cultivate healthy soil microbiology thus maximizing plant performance. We do all this without compromising or taking shortcuts that would hinder the health of the planet. Here we’ve opted to choose more sustainable inputs - like biochar - which stores harmful greenhouse gasses while also making your soil extremely happy. We take this commitment to quality soil a step farther by operating a lab space where all of our soils are strenuously tested & analyzed. Below, I provide a brief overview of the experimentation & research work that has led me to these specific formulations:

Houseplant mix: The formulation that broke the mold

Our foray into formulating a peat-free, biochar based mix began with our houseplant soil that really cemented the base formulation for our future soils.

The first step towards crafting a sustainable potting mix was to remove peat moss and replace it with both compost and biochar. Peat moss - the typical base in standard potting mixes - is extracted from peat bogs which store about a quarter of all land-based carbon so the extraction process releases obscene amounts of carbon dioxide. Instead we’ve opted to use biochar which stores carbon dioxide while also vastly improving soil health. The combination of compost and biochar offer similar benefits to peat while avoiding the negative environmental impacts. 

After replacing peat, the main problem I faced was how to replace perlite as it’s the most common aeration amendment but sadly it is not a renewable input. Compost and biochar alone aren’t ideal as a complete potting soil because they are rather dense together and they don’t offer ample pore space for roots. I conducted experimental growth trials and water holding capacity tests to determine what could replace perlite and came to the conclusion that pine bark fines offered the same benefits as perlite while also being a much more sustainable input. Most recently, a chunkier wood-based compost was added to ensure that aeration and drainage were optimal. And finally, worm castings were included as they offer an array of benefits from healthy microbiology to improved soil structure. 

Cacti mix: Explorations into increased biochar capacity

The cacti mix was designed with the same set of base ingredients as Houseplant - biochar, compost and pine bark fines. Both pumice and sand were introduced to further lower the water holding capacity of the soil & improve drainage as to accommodate the needs of cacti & succulents. The cacti mix has been fun to experiment with because it gives me a bit more leeway to test out higher percentages of biochar in the mix. For the past few months, I’ve been trialing nut shell biochar as a means to increase the chunkiness of the mix. The increased biochar mixes have shown equal amounts of growth as compared to a standard potting mix and our current production mix. My hope is to continue to push the upper limits of biochar in a mix without discounting plant performance. 

Seedling mix: The power of biochar & worm castings

As someone with a background in farming, the seedling trials were extremely fun for me. I ran 100+ germination experiments against the likes of a standard peat-based potting mix. Rather than create a sterilized mix free of soil microbiology, I’ve chosen to embrace the power of worm castings as they are possibly the most important input for seedlings. Both my own experiments and various studies have shown that biochar & worm castings speed up germination time while also boosting root and shoot growth. Worm castings provide essential nutrients and soil microbiology while biochar serves to store nutrients & water long term while also providing carbon to microbiology that is crucial in the carbon cycle. The two inputs were clearly made for each other & set up seedlings for sustained, healthy growth. 

Plant Food: Rejecting synthetic fertilizer & supporting the soil

Formulating a Plant Food mix without the use of synthetic fertilizers has been a challenge for sure. Synthetic fertilizers often have an overabundance of nutrients while also harming the soil microbiology - essentially the soil as a living organism is completely ignored. I prefer organic fertilizers but even then, many of the available products rely heavily on pumping nutrients into the soil (albeit they are organic) but they neglect to include soil microbiology. My belief is that in order to grow happy plants we must nurture healthy soil - our Plant Food mix relies heavily on biochar, compost, and vermicompost. Additionally, I included an input called ‘charkashi’ that is a symbiosis between biochar and bokashi! On top of these, I’ve also added kelp meal & alfalfa meal as they are renewable inputs that offer an array of nutrients and minerals to our mix. The growth trials showed that Rosy fared favorably against a standard fertilizer & our lab analysis shows optimal amounts of nutrients & microbiology. 

Biochar toxicity: Testing the upper limits of biochar

I am always running a few experiments that try to push the bounds of our research, or in other words are completely wacky - my most recent iteration has been testing various percentages of biochar in the soil. Once again, nut shell biochar was used for this experiment. Our standard potting mix was tested against experimental mixes that included an extra series of percentages of biochar. To my surprise, the houseplants in the higher percentage biochar mix performed slightly above par as compared to the other mixes. My question is, at what point does biochar begin to show diminishing returns? As a company committed to high quality plant performance & sustainability, adding more biochar to the mix just makes sense. There aren’t a plethora of studies that speak to the upper limits of biochar use in soil so much of this work is purely out of interest. From what I’ve seen so far, biochar may have the capacity to partially replace other inputs like sand, pumice, compost, etc. 

What’s next? A sneak peek into the lab

While I’m always amending our current soil mixes, I’m also in the lab working on new mixes that will be revealed in the future. Thanks for tuning in & engaging with my work. I hope that this illuminates some of my work with Rosy. Please feel free to reach out if you want to talk soil or have any questions.


Lead Soil Researcher, Rosy Soil