How To Grow Mega Cannabis Buds With Silica

Silica is a relatively new addition to cannabis feeding regimes. Though silicon is one of the most abundant compounds in the Earth's crust, its role in plant growth is little known, at least compared to other nutrients.

Though not considered essential, there is a growing belief that adding silica to cannabis plant solutions (or adding it separately) can increase growth, yield, and overall potency, whilst affording added protection against pests and fungi. It is not as well-documented as other nutrients, so we’ve put together a guide on how to safely and effectively use potassium silicate in your cannabis grow-op.

What Is Silica?

Silica (silicon dioxide) is a natural oxide of silicon. It is found most abundantly in quartz and sand. However, silica is also found in living organisms, where it is used to strengthen cell walls—and therefore the overall organism’s structure—and boost defences against pests. This process is known as silicification.

Cannabis and Silica: What Are the Benefits?

Silica can offer your cannabis plants a significant number of benefits. Though it is not considered one of the 17 essential nutrients without which cannabis growth will be severely hampered, feeding your plant with silica could increase the quality and yield of your crop.

The process of silicification within your cannabis plant has manifold benefits. The primary one is the strengthening of cell walls, which makes for a more robust plant, but also assists in the uptake of nutrients and water by strengthening the passageways through which they flow. But that's not all; silica in the cannabis growing medium also presents various benefits.

Let's dive into all of these benefits a bit deeper.

Better Growth

By increasing the speed of cell wall creation, your cannabis plants will grow faster and with more vigour. The upshot of this? More growth means more bud at the end of it. Being larger and stronger, your plant is able to squeeze out more flowers, and these are often larger and healthier.

Better Uptake of Nutrients

Due to the improved strength of cell walls, plants will be able to uptake water and nutrients more efficiently than otherwise. This leads to healthier, more robust growth. And, following on from the previous point, as your plant will be growing larger and faster, more efficient uptake of nutrients is necessary to make this sustainable, and to maintain the overall quality of your plant.

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Robust and Resistant

The hardier cell walls make it more difficult for pests and disease to take hold of your plant. Both on a macro level (the plant’s surface is tougher) and on a micro level (the cell walls are more difficult to penetrate). SIlica also aids in the antifungal immune response. If a fungal infection threatens the plant, it will transport silicon to the affected site, which will protect the plant.

Prevents the Uptake of Toxic Metals

Silicon in the substrate competes with metals. An abundance of heavy metals can be toxic for your plant. By adding silica to the growing medium, you mitigate the opportunity for unhealthy uptake of these compounds.

Regulates Uptake of Nutrients

The uptake of macro and micronutrients is affected by silicon; specifically nitrogen and phosphorus. Uptake of nitrogen is increased, which is of benefit to your plant, while phosphorus uptake is stymied by silicon. As phosphorus can quickly reach toxic levels, adding an element of control to your grow is a major benefit.

Better Buds

Through all the above, the overall quality of your bud production will be improved, and this is what it’s ultimately all about. Your healthier, more vigorous plant will produce more buds, with more THC and bigger overall growth. Moreover, the trichomes will be more resilient long after harvest, meaning that they will last longer and taste fresher for a good while.

How To Use Silica With Cannabis Plants: Essential Tips and Tricks

To add silica to your soil, it must be added to water in the form of potassium silicate (K₂SiO₃). This is its salt form, which is water soluble. One thing to be aware of is that potassium silicate is alkaline and will raise the pH of your substrate. Be sure to check before and after feeding to ensure you can make any necessary adjustments to your substrate.

By adding silica in a water-soluble form, the roots of your plant will be able to use it. That which isn’t taken up by the plant will sit in the soil, ready to be used at a later date and offering various protections whilst present.

Another thing to bear in mind: silica is different to other nutrients, and should therefore be stored separately. Whereas most nutrients can be stored in a single solution, silica requires a pH higher than 7 to remain soluble. Therefore, add it to a nutrient mix immediately before administering to the soil.

When To Start and Stop Using Silica With Cannabis?

You should begin giving silica to your plants early during the vegetative stage, and should stop when they reach the flowering stage. At this point, most of the growing will be complete, and the additional silica for cell wall growth will no longer be necessary. Going beyond this will actually damage your final product.

As the main benefit of silica is increased cellular growth, it is obvious why it is most necessary during the vegetative stage. Plants will make the best use of silica when growing and strengthening their stems and branches.

A final word of warning. If you use silica during bloom, it will undo much of the good work it has done during the vegetative stage. As the plant is growing, increased toughness and durability are desirable. However, this trait will also transfer to your buds. The consequence? Tough buds with decreased overall quality. Whilst it won’t wreck your grow entirely, it will negate the point of using silica in the first place. Therefore, be aware and stop feeding at the appropriate time!

Using Silica With Soil

Using silica is not an exact art. Depending on which brand of potassium silicate you buy, the amounts will vary a little. As a rule of thumb, 100ppm is about right. As a powder, this will be around 125 grams; if in liquid form, it’ll be between 2 and 3 millilitres per 10 litres of water. But again, for exact measurements, go by the instructions provided.

Administer the silica as often as you do your other nutrient solutions—or less—as you don’t want to upset the balance. Better to underfeed than overfeed, as is the case with most nutrients. However, with silica this is even more the case. As a plant may grow well without it, underfeeding should not have any adverse effects.

Using Silica With Hydroponics

Silica and hydroponics is a tricky one. Often, hydroponically grown plants can be weaker than soil-grown ones, and this is directly due to a lack of silica. The reason it can be so difficult is that silica cannot be stored in acidic solutions; therefore, the solutions that hydroponically grown plants live in are unsuitable for it.

However, there is a way around this. Mix your silica separately in a solution and bring this up to the correct pH level, then add it to the main nutrient solution. This could take numerous litres of water. It is worth adding this gradually over a period of time, instead of dumping it in at once. By doing this, you mitigate the risk of inhibiting the uptake of other nutrients.

Whilst silica is beneficial for hydroponic plants, it can also do more damage. If it raises the pH of the main nutrient solution too much, then it will go cloudy. This will stop the roots from properly uptaking nutrients, and will inhibit growth. Therefore, if you’re going to use silica, use it carefully and with restraint.

Potassium silicate can also be administered as a spray, which alleviates many of the major concerns. However, the efficacy of administering it this way is dubious. Whilst it seems that it definitely does provide some protection against pests and fungal infection, whether it can be properly taken in and used on a cellular level is up for debate.

Around 100ppm is thought to be a good potassium silicate level for hydroponic grows. To reiterate, always err on the side of caution. Silica is not essential, but it could ruin your hydroponic grow. At most, add it as regularly as your other nutrients.

Can Cannabis Plants Overdose on Silica?

Silica is a great addition to your cannabis feeding regime. If growing in soil, the risks are minimal and can be easily avoided or fixed. The major issue to watch out for is upsetting the pH balance and making the soil too alkaline. However, this can be fixed by acidifying the solution before adding it. As long as you follow the instructions and don’t add silica in abundance, you shouldn’t run into any problems.

But, stop using silica once your plant starts flowering! This is the major rule, and one that is often overlooked, making the whole use of silica redundant. All of the benefits to your buds will be lost if you continue to feed them silica during bloom.

With hydroponics, yes, you certainly can overdo silica. Therefore, proceed with caution. It’s a fine balance, though, as this is where silica offers the most benefits, too.

To conclude, if used appropriately and in moderation, silica will give you robust plants with greater harvests and stronger buds. As this is what most people want from cannabis growing (why else would you do it?), it is a fantastic addition to any weed plant’s diet.

Adam Parsons

Professional cannabis journalist, copywriter, and author Adam Parsons is a long-time staff member of Zamnesia. Tasked with covering a wide range of topics from CBD to psychedelics and everything in between, Adam creates blog posts, guides, and explores an ever-growing range of products.

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