For greenhouse growers in floriculture and controlled environment agriculture (CEA), growing media is often treated as a cost to manage rather than an input to optimize. As a result, many operations opt to reduce the upfront cost through cheaper mixes or substitutions.
While a lower price is ideal for any grower, using cheap growing media can have expensive consequences.
Energy and labor are the most prominent pain points for greenhouse growers. But growing media directly influences both. By investing in the right one, growers gain stronger operational efficiency and long-term ROI.
Peat vs. The Competition
In the last decade, soilless substrates have grown increasingly popular due to sustainability concerns around peat. While many greenhouse growers have tried coconut coir and rockwool as an alternative, peat-based media continues to have the edge in the market.
Peat has an ideal balance of water-holding and aeration. Its smaller pore spaces hold water, while the larger ones hold air, making it easy to maintain that balance.
The ideal pH level for crops tends to range between 5.5 to 5.8. Peat has a starting pH between 3 and 4.5 due to its natural acidic chemical property. This makes it easier for growers to amend pH with lime to reach optimal levels.
Adding lime to peat enables the pH to resist change throughout the growing cycle and remain in an optimum range. This is a huge benefit for peat, especially compared to coconut coir.
Coconut coir starts at a pH level of 5.5, and that number tends to rise when other amendments are added to it. It’s much easier to raise pH levels than to lower them when it comes to reducing labor and the risk of crop stress.
Putting Sustainability in Context
There have been continuous peat shortages dating back to 2020, forcing many growers to look for sustainable growing media solutions. While peat accessibility is a strong concern in European countries, it’s less of an issue in North America.
Peat bog can be restored in 15 to 20 years in Canada, where it can take 100+ in Europe. This means European growers are using peat much faster than it can be restored—they don’t have the flexibility to gradually transition to other mixes like North American growers do.
Still, peat isn’t the only growing media with an environmental footprint.
Rockwool and coconut coir carry their own sustainability baggage, and at a higher price point. On top of being more expensive, rockwool—a manufactured substrate made from spun mineral fibers—goes directly to the landfill after one use. Coconut coir is composed of ground-up coconut husks from Sri Lanka and Thailand—using coconuts there isn’t beneficial for the local ecosystem either.
While growers in North America aren’t currently facing the same peat concerns, the status quo isn’t permanent. This underscores why they should start paying attention to biochar sooner rather than later.
The Case for Biochar
To combat the growing concerns around peat’s sustainability, Sun Gro released biochar mixes. Biochar eliminates the need for perlite—a mined, nonrenewable material—with a renewable resource derived from wood chips, plant residues, and agricultural waste. Sun Gro’s biochar aggregate comes from 100% soft wood waste streams.
Beyond sustainability, biochar brings agronomic benefits that growers can measure.
For instance, biochar offers the same structure, aeration, and drainage as perlite. It also improves nutrient holding, water holding, and reduces ammonium toxicity. The reduction in irrigation lowers labor and energy costs, two of the biggest overhead costs for greenhouse operations. Plus, when added at a high enough percentage to the mix as an aggregate (15%+), growers may experience better rooting and overall plant performance.
Biochar has the potential to be the future of growing media. However, many greenhouse growers are hesitant to use biochar since they’re accustomed to using perlite mixes. As perlite becomes more expensive, biochar may be their only option.
That’s not to say that biochar is inexpensive by any means. Currently, biochar mixes are about the same price as perlite ones, but that won’t always be the case—growers could see biochar become the more cost-effective option within a few years.
At the very least, Sun Gro aims to keep the price consistent so biochar mixes are in line with perlite mixes in the future.
Growers likely won’t move away from peat completely. But instead of using peat-perlite mixes, they will start using peat-biochar and peat-wood fiber mixes instead to help offset their need for perlite or to stretch their peat supply without compromising the quality of their mix.
Peat-based growing media isn’t going away, but the inputs surrounding it are changing rapidly. Growers who treat those changes as an opportunity—rather than waiting until perlite prices force their hand—will protect their margins when it matters most while maintaining or even improving their plant quality.