Silicon: The Non-essential Plant Nutrient with Big Benefits

By Monica Mansfield
Published: March 1, 2017 | Last updated: June 14, 2022 03:24:03
Key Takeaways

Next time you’re browsing through nutrients at the local hydro shop, reach for a bottle of silicon supplements. Though not essential, it’s probably worth spending that little bit extra on. Here’s why.

When you walk through your local hydro shop, it is easy to get overwhelmed by the number of fertilizers available. They all promise big results, and it can be tricky to know which fertilizers and supplements are worth their price tags and which aren’t.


Most nutrient lines carry a silica supplement, and you may wonder if it is necessary or beneficial to spend your hard-earned money on one. Well, it depends.

Silicon is not an essential nutrient. Plants can grow in hydroponic solutions without any silicon added. However, it is considered a beneficial micronutrient. You know those little packets that come with cut flowers to make them last longer? They are full of silica.


Plants grown in soilless media or hydroponic solution without silicon are usually not as healthy or productive as their counterparts grown with silicon supplements or in rich, organic soil, which usually has plenty of silicon available (you can test your soil to be sure).

So, what exactly is silicon, and is it the same as silica? Silicon is the second-most abundant element in the Earth’s crust and is used to make everyday items such as bricks, computer chips, solar panels, and glass. It makes up about a quarter of most rocks. Silicon and silica aren’t exactly the same, but they are related.

Silicon is a chemical element, while silica is the common term for silicon dioxide, the combination of silicon and oxygen. Together, silicon and oxygen create a wide range of silicates, including quartz, tridymite, coesite, cristobalite, and stishovite. There are also silicates that include other elements such as feldspars, which also contain sodium, aluminum, potassium, and calcium.


The most common source of silicon in commercial fertilizers is potassium silicate. It is completely available to the plant and is water-soluble. It is also alkaline, so you need to be sure to monitor your pH closely when adding it to your nutrient solution. In fact, it can be used strictly to increase your pH when it is at a high enough concentration.

Silicon’s benefits are substantial and can mean the difference between a good yield and a great yield. Silicon strengthens cell walls and stems, creating a plant that can bear the weight of large fruit.


A larger stem also means that a plant can uptake more nutrients and water at once, allowing the plant to grow larger faster. When fed to cuttings and seedlings, silica supplementation has been known to lessen the shock of transplanting and strengthen the stems at a faster rate.

Silica also aids a plant’s ability to withstand stress from temperature and drought.The strong cell walls are better able to expand and contract during extreme temperature changes so that the stress has less of an impact. This is especially helpful outdoors in the cooler seasons, when temperatures can drop drastically at night. It also helps a plant hold onto more water during transpiration, which is good during the hot, dry days of summer.

Pests and disease will have a harder time attacking your plants when silicon levels are up, too.Silicon builds up in plant tissues and bind together to make it harder for pests to eat through the tissue.All this hard work takes more of the pests’ energy and slows down their reproductive rates.

Silicon has also been shown to ward off fungal diseases such as powdery mildew, rust, and pythium. Some studies have also shown that silicon specifically builds up in areas of infection on plant tissue to protect the plant from further disease. Foliar feeding with silicon is an effective preventative practice, especially if your environment is the hot and humid conditions in which fungal diseases would thrive.

Many studies have been conducted on the effects of silicon in plants. A 1986 study on how the micronutrient affects cucumbers found many positive benefits. Most notable were the resistance to powdery mildew, more chlorophyll content in the leaves, increased root weight, and delayed senescence.In other words: the plants had more roots and greener, lusher foliage,leading to more fruits.

A 2014 study found that silicon protects plants against metal toxicity by decreasing metal availability in the plant and affecting metal distribution inside the plant. The same study also found that silicon mitigates the symptoms of iron deficiency in plants.

Research at the University of California, Davis, has studied the effect of silicon in dwarf citrus, chrysanthemums, and roses. Their results showed smaller pest populations on the citrus and chrysanthemums. Similar research discovered that there was a decrease in leaf miner populations on citrus and chrysanthemums when potassium silicate was added to their water.

Some plants benefit from this element more than others. For example, rice and sugar cane accumulate large amounts of silicon, whereas cucumbers accumulate a moderate amount and tomatoes accumulate very little. For silicon accumulators, it is absolutely beneficial to add silicon to your nutrient solution, especially if you’re growing hydroponically.

There are plenty of silica products on the market. When choosing a liquid, opt for the highest concentration to stretch your dollar the farthest. You might also consider a biogenic silica powder. Although it isn’t 100 per cent water-soluble, about 25 to 30 per cent of the powder will dissolve for immediate use by the plant and the rest will stay in the root zone and release over time.

Biogenic silica powder also makes for the perfect companion to beneficial bacteria because its pH neutral and won’t make your solution as basic as the liquid version will. The bacteria will hitch a ride on the silica particles and use them to attach to the plant’s roots once the silica particles lodge themselves within the root zone.

So, if you want to boost the overall health, vitality, and yield of your crop, I recommend using a silica supplement in your nutrient program, especially if you are growing hydroponically. It is one of the simplest things you can do for the greatest return come harvest time.

Liked this article? Read about other important plant nutrients: The Full Menu: Beneficial Elements for Plant Growth


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Written by Monica Mansfield | Homesteader, Owner & Writer of The Nature Life Project

Profile Picture of Monica Mansfield

Monica Mansfield is passionate about gardening, sustainable living, and holistic health. After owning an indoor garden store for 5 1/2 years, Monica sold the business and started a 6.5-acre homestead with her husband, Owen. She writes about gardening and health, as well as her homestead adventures on her blog at

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