Is silica used as a nutrient in hydroponics? I was shocked when I first heard this years ago because I had always thought of silica as an element that could cause respiratory problems. So the big question is: Is silica bad for your hydroponic vegetables?
Generally, silica is a safe nutrient to use in hydroponic gardening. Contrary to what many believe, silica improves the immunity of hydroponically grown plants by forming a barrier in the plant’s cell walls. Thus, it protects vegetables from plant diseases, environmental stressors like drought and salt, and pests.
In this article, I will be presenting facts based on science that will help you know silica better. More myths will be debunked as you read forward!
When used properly in gardening, silica does not cause serious human diseases, thus it is safe to use in hydroponics. More importantly, hydroponic produce such as fruits and vegetables grown with silica is safe for humans.
Silica in its fertilizer form does not pose any pathological risk for hydroponic gardeners. It can only cause respiratory problems when in the form of dust.
At some point, I know you are also alarmed by reports of silica being harmful to our lungs.
The Truth: Silica is only harmful in its dust form.
But where else can you get that? Ceramics, soil, mines, bricks, and construction supplies! Well, I do not see any hydroponic gardening products there—so, fortunately, we are safe!
Reports of lung diseases associated with silica are more prominent in the mining and construction industry. In such cases, people are exposed to large amounts of fine silica particles for a long period.
Silica is used as a nutrient solution for hydroponic gardening. It can be used as a supplement for hydroponic plants from seedling to harvesting stages.
Contrary to the famous myth, silica is actually a necessary element that plants need.
The Truth: Silica is composed of a micronutrient, silicon, that helps crops have a strong plant structure.
Another factor that probably gave you a negative perspective of silica is its absence in hydroponic solutions. If you will observe, silica is absent in most hydroponic nutrient solutions available on the market.
So is this because it is not safe? The quick answer is NO.
Silica has a basic pH value, which means it has a high pH. When silica is combined with other nutrients, it becomes unstable. Thus, if silica is mixed with other liquid hydroponic nutrients, it tends to bond with other elements and become useless.
This is the reason why most hydroponic gardeners add silica before adding the base nutrients such as nitrogen, phosphorus, and potassium and additives like calcium and magnesium.
Hydroponic vegetables grown with silica have stronger plant structure, higher resistance to environmental stress such as drought, and higher immunity to biological stress such as plant diseases.
The Truth: Silica, in its nutrient form, is absorbed by plant tissues and strengthens cell structure, resulting in higher quality and safe-to-eat vegetables.
The principle of using silica is the same as other nutrients in fertilizers. Once absorbed by the roots, they move like workers going to their offices! So our employee, Silica, goes to the stem, leaf, flowers, and fruit departments to build strong cell structures.
Silica can be applied to the hydroponic solution of your veggies such as lettuce, tomatoes, cucumbers, peppers, eggplants, and even herbs!
Know more about this in our article on safety of hydroponic vegetables.
More functions of silica will be revealed in the next sections!
Silica, also known as silicon dioxide, is an abundant mineral in soils and rock deposits. The most common use of silica is in the construction industry, as glass and ceramics, due to its hard texture and extremely high melting and boiling points which are 1710℃ and 2230℃, respectively.
I summarized the properties of silica in the table below for you to have an easy look.
|State||Solid (Crystalline, in form)|
|Hardness||Hard (Rating of 7 on Mohs Hardness Scale)|
|Reactivity||Reactive with most hydroponic nutrients|
You might be wondering, what is the significance of these properties of silica? Well, I think these are the reasons why silica is somehow seen as an antagonist in the food production world.
How you might ask?
Perhaps, some people saw these properties and immediately concluded the myths that we discussed a while back. The development of the myths might have gone like this:
- Since silica is a hard mineral, it is a dangerous nutrient!
- Why should I place silica in my hydroponic water if it is used in the construction industry?
- I cannot dissolve this mineral considering that it has high melting and boiling points, so how would my plants absorb it?
To remove these concerns off your shoulders, I would like to emphasize that these properties are for pure silica. I will repeat, pure.
Silica hydroponic products available in the market are not made from pure silica. Hydroponic products such as the one below include potassium and hydroxyproline-rich glycoproteins—both are also agents that thicken the cell wall.
Silica increases the immunity of hydroponic plants by protecting them from environmental and biological stresses.
Specifically, silica benefits hydroponic plants by doing the following.
Silica goes directly into the cell walls of the plant parts, thus it functions immediately to strengthen cell structure.
Since silica is deposited in cell walls, it keeps the cell integrity intact, so that each cell in the plant will not easily dry out.
Silica was found to be a good balancer of manganese, aluminum, phosphorus, and iron toxicity in hydroponic plants. When these elements build up, they tend to harm cells by blocking water and oxygen transfer. Thus, silica aids by balancing these salts.
Silica acts like a shield that protects the plant cells against any plant disease invasion.
A study revealed that silica is effective in controlling fungal pathogens such as botrytis. To let you know more about botrytis, it is a common fruit and vegetable fungal disease that is characterized by development of molds. They can reproduce easily through air or water transport.
A common water-borne pathogen is root rot. The root cells are protected by silica, which acts as a barrier against root pathogens.
Because of the silica content inside the leaves and stem, pests such as sucking insects and leaf hoppers are driven away. (For these insects, eating plants with silica in them is like eating a huge ball of wasabi! Yikes!)
Hydroponic plants grown with silica gain more harvest due to the less incidence of stressors. With less environmental and biological stresses, the plant can devote its energy to develop each plant part and be productive.
Silica strengthens the cell wall thereby building protection for hydroponic vegetables against plant diseases, salts, and insects. Since the cell wall acts as the firmness indicator in vegetables, silica helps in producing harvest which are higher in quality.
Consider the cell wall to be the balloon in a paper mache balloon. And, silica is the glue used to strengthen the paper. If the balloon mache is not protected with the glue and paper, then it will easily pop.
This scenario is somehow parallel to silica and the cell walls of hydroponic vegetables.
When the cell walls are not strengthened, the cells of vegetables are more vulnerable to sustaining damage. Some of these damages include insect attacks and the development of plant diseases.
Hydroponic silica is marketed as a distinctly separate nutrient solution because it negatively reacts with other nutrients such as nitrogen and phosphorus.
If you are looking where to get silica supplementation for your hydroponic plants, browse the following recommended products on Amazon.
Silica Blast from Botanicare is easy-to-use with direct instructions. It can be used both for hydroponic and soil gardening. You can apply this every 5 to 7 days, but make sure to adjust your nutrient water’s pH after application.
Silica boost from Bloom City is formulated by plant scientists and is 100% compatible with every hydroponic nutrient system. To use this product, it must be added first before any other hydroponic nutrient.
Do fertilizers naturally have silica in them?
Silica is packaged separately because it does not mix well with other elements in hydroponic fertilizers. Unlike other nutrients such as nitrogen, phosphorus, and potassium, which are available in their natural state, silica can be purchased as a supplement.
What other nutrients have the same effects as silica?
Calcium, like silica, is an essential nutrient that can help to strengthen cell integrity. This is why calcium is also used as an additive in hydroponic solutions. It is typically marketed with magnesium and used for leafy, fruiting, and herb vegetables.
Silica is suitable for hydroponic vegetable cultivation. Silica has several benefits for plant growth and development when used as a fertilizer, which is contrary to myths about it causing respiratory diseases and being hazardous.
Silica helps strengthen the hydroponic plant’s immunity by building barriers of protection in cell walls. This process then decreases the vulnerability of the hydroponic plants to diseases and insect pests.
In the commercial aspect, silica is available as a hydroponic supplement due to its chemical properties such as pH and reactivity. It must be separated from other nutrients because it may interact with other nutrients, such as nitrogen and phosphorus, and lose its function.
- “Silica, Crystalline” by Occupational Safety & Health Administration in United States Department of Labor
- “Respiratory Health Hazards in Agriculture” in American Journal of Respiratory and Critical Care Medicine
- “Effect of Silicon Plant Growth and Drought Stress Tolerance” by Janislampi, K.W. in Utah State University
- “Silica” by NSW Government in New South Wales Government Australia
- “A Case for Silicon Fertilization to Improve Crop Yields in Tropical Soils” by Meena, V. in Proceedings of the National Academy of Sciences