Growth Technology SILICA 1 Litre

From the clever gang at Growth Technology comes GT Silica, known as 'Nature's Bodyguard'. Also available in 250ml size (this is the 1 litre size).  

One 5ml pipette included FREE with every order (not one per bottle). Get extras here: 5ml pipette or 3ml pipette.

Why give plants silica?

Silica is a natural powerhouse nutrient abundant outdoors but missing indoors. Adding Silica to your feeding routine gives indoor plants the protection that nature would normally provide, making plants stronger and hardier, both physically stronger and by supporting stronger defences against pests, diseases and environmental stresses.

It's like a bodyguard for your plants!

These benefits of Silica have been extensively studied and proven. More recently, silica's started being used for variegated foliage. Early days but there's promising anecdotal evidence from hobbyists and growers that silica helps prevent or delay premature browning of naturally weaker variegated leaves. Watch this space!

Which plants need GT Silica?

All plants benefit from Silica but not all plants need it. Outdoors if you test your soil you may find silica in abundance due to soil water, however indoors silica is not naturally available. Silica can be used as a pro-active protectant for any plant not already getting silica naturally, or where soil water is deficient.

Silica can also be used defensively for plants under stress or attack, however is best used proactively 'little and often' as silica is not a mobile nutrient (meaning plants can't correct a deficiency by shifting silica within itself). Plants rely on their substrate to meet their silica needs.


Silica also strengthens sensitive or weaker plants prone to stem weakness, browning and wilting, and helps plant's prone to attack by pests, fungus such as root rot, powdery mildew, leaf rot and other diseases.

Is Silica best given via the roots or leaves?

Silica is best made available to plants via the roots, but when more urgent action is required, use GT Foliar which provides a boost of silica as a foliar spray for more immediate uptake, then continue with GT Silica long-term provided through the roots. 

What's in GT Silica?

A concentrated blend of silicic acid and potassium hydroxide (called potassium silicate). Considered the superior form of silica for plants. 

Silica for environmental stress

Plants deposit silica in their cell walls, strengthening roots, stems and leaves, acting as a protective barrier between the plant and the environment. Silica increases physical strength for plants prone to weak stems, browning, drooping or wilting leaves. The protective barrier also helps plants handle water and temperature stress. Reducing the impact of under- and over-watering as well as extreme hot or cold temperatures.

Silica for pests

Silica is part of nature’s defence system against pests that feed on roots, stems and leaves, such as fungus gnat larvae, mealybugs and root mealies, aphids, thrips and spider mites.

As well as making the external barrier harder for pests to penetrate and feed, silica also makes plants less palatable and harder to digest, slowing insect growth and reproduction.

Silica's been shown to more quickly block the flow of sap when a plant is under attack from sucking insects like aphids and mealybugs. Plants have also been shown to continue to send silica to damaged areas after the threat is gone, so silica is also thought to assist with faster recovery.

Directions for use

How much?

You can mix up to 5ml GT Silica to 1 litre water (to maintain 20ppm silica) but unless you know the existing silica levels in your soil and water, start with less - from 1ml per 1 litre water - especially if there are existing silica sources in your water or substrate (5mls is full strength).

Although the second most abundant element in the earth’s crust, a component of most rocks, the concentration of silica in soil water is not that high (rocks don’t tend to be all that soluble). Silica concentration in soil water generally doesn’t get above 20ppm (the level GT Silica maintains at the 5ml dose).

Silicates are very alkaline in their concentrated form in the bottle. Either wear gloves when handling the liquid, or take care not to spill on your skin (or clothes). It's best to just use a 5ml pipette (supplied free) to get how much you need straight from the bottle. Safety data sheet available here.

Add Silica separate to your nutrient solution, or if mix-feeding with fertiliser, always add silica first and stir, wait 15 minutes, stir again, then add your GT Focus fertiliser of choice to the mix before watering roots. 

How often?

Silica is not a mobile nutrient. Plants rely on a regular supply. For best results, add GT Silica every time you water or every week.