A knight in silicon armor

Two plant pros took the stage at the most recent Cultivate conference to shine a long-overdue spotlight on a powerhouse element that’s been hiding in plain sight: silicon. Their message? It’s time to stop ignoring what’s right beneath our feet and start leveraging it in our soilless systems. In their session, “Silicon in Growing Mixes: Advancing Substrate Technology,” Connie Johnson, R&D scientist at SunGro Horticulture , and Patrick Veazie, graduate assistant at North Carolina State University, delivered a data-packed presentation that proved silicon isn’t just some geological footnote. It’s a game-changer for greenhouse growers who want healthier, hardier and more stress-resistant plants. Despite being the second most abundant element in Earth’s crust, silicon is largely absent in soilless growing media, which means most greenhouse and container crops are missing out on its benefits. Peat, coir and perlite may be popular substrate choices, but they don’t offer meaningful amounts of plant-available silicon. And because silicon is not considered an “essential” nutrient, many growers have never thought to add it. That mindset, the speakers argued, needs to change, and fast. “Silicon is what I like to call a stress shield,” said Johnson. “It gives plants an extra layer of defense, almost like armor.” Although silicon isn’t technically classified as essential, the Association of American Plant Food Control Officials officially recognizes it as a beneficial plant substance, a designation that’s growing in credibility as the research stacks up. Over the past 20 years, scientists and growers alike have begun to uncover how powerful silicon can be, especially in ornamentals. According to Johnson, research shows that silicon supports a wide range of plant processes, improving germination, root growth, plant structure, flowering and overall yield. Where it really shines is in its ability to help plants handle stress, both biotic (like pests and diseases) and abiotic (like heat, drought, cold and salinity). “Think of it like an insurance policy,” Johnson said. “Silicon may not make your plants invincible, but it helps them bounce back faster and sometimes avoid the damage altogether.” Those aren’t just hopeful claims. Veazie presented compelling data from trials on poinsettias, basil and hemp, showing just how diverse silicon’s impact can be. Poinsettias treated with silicon maintained their color, strength and visual appeal longer – meaning longer shelf life, a key selling point for retailers. Basil plants grown with silicon demonstrated a greater tolerance to cold temperatures, which could help protect greenhouse operations during seasonal temperature dips. Meanwhile, hemp plants showed significantly reduced instances of powdery mildew, a fungal foe that’s notoriously difficult to manage. In every case, silicon seemed to act as a kind of cellular reinforcement, strengthening stems, bolstering roots and helping plants shrug off environmental and pathogenic pressure. So why aren’t more growers using it? According to Johnson, part of the issue is a lack of awareness. Many growers simply don’t know silicon can make such a difference, or that it’s even missing from their media in the first place. For those who do know, the application questions can sometimes cause hesitation. But Johnson broke it down in practical terms. Growers have two main options: apply silicon regularly through liquid nutrient solutions, typically 50 to 100 ppm once per week, or incorporate silicon-rich materials directly into the growing media before planting. “Consistency is key,” she said. “Silicon isn’t stored in plants the way some nutrients are. If you want to see benefits, you need to keep it in the root zone throughout the crop cycle.” For growers who rotate crops or work with quick-turn plants, a pre-loaded growing media might be the simplest solution. For long-cycle or high-value crops, a weekly feeding can be built into the fertigation schedule. Either way, the speakers emphasized, the results can be well worth the effort. As soilless growing becomes more sophisticated, and more essential, growers are seeking out ways to future-proof their production. Silicon offers a sustainable, science-backed tool to do just that. It’s cost-effective, crop-friendly and compatible with most existing systems. As extreme weather events and pest pressures become more common, Veazie believes silicon could become a frontline tool in every grower’s toolkit. “Stress is inevitable in agriculture,” he said. “But silicon gives your plants a fighting chance. It prepares them for what can come next.” In an industry where the line between success and struggle is increasingly thin, the value of any advantage, especially a natural, non-toxic one, is impossible to ignore. Silicon may not have the flash of synthetic boosters or high-tech gadgets, but it has something even better: proven results. As Johnson reiterated, silicon doesn’t just help plants look good. It helps them perform. Stronger roots, sturdier stems, more efficient water use, greater stress tolerance – it all adds up to a more resilient, more profitable crop. That’s why both speakers encouraged growers to start experimenting now, whether that means testing silicon on a single variety or working with suppliers to build it into their mixes. “We’re not talking about a magic bullet,” Johnson said. “We’re talking about a smart move. A strategic move.” As more growers look to build resilience into every layer of their operation, from lighting to labor to logistics, adding silicon to the substrate might just be one of the most powerful decisions they can make. Because when the growing gets tough, the tough don’t just survive, they thrive. Sometimes, they do it with a little help from an element they never even knew they needed. With silicon stepping into the spotlight, the future of fortified, flexible and fearless growing is already taking root. by Enrico Villamaino