Silica, Auxins and Cytokinins: A Trio of Cannabis Plant Additives

There are many types of additives on the market; being aware of what they do is the first step in knowing how to make the best use of them.

Silica Strengthens Cannabis Plants

Silica is a popular additive and there are several commonly-available brands from which to choose. Although not usually considered a required nutrient, if available to the plant, silica can improve health. Silica is primarily stored in the plant in the spaces between the cellulose micelles, which reinforces the epidermal cell walls, thereby strengthening them. In much the same way that steel rebar strengthens cement walls in buildings, silica adds strength to plant cells.

Having improved cell wall strength is beneficial in a variety of circumstances. This helps to provide structure to cells, reducing the tendency to wilt - especially in dry conditions. Since the plant is less apt to wilt, the leaves stay turgid and open, increasing the opportunity for photosynthesis and thereby improving growth. When conditions are cold and wet, the additional strength helps to fend off invasive fungal attacks by making the epidermal layer more difficult to penetrate. For the same reason, the additional toughness of the plant's skin also helps to make the plant less attractive to insect attacks. Silica also improves plant tolerance to manganese, aluminum and salt stress.

Plants take up silica in the form of silicic acid or silicates, with 'monocots' or plants with a single seed leaf (cotyledon) usually absorbing to a higher percentage than 'dicots' or double cotyledon plants, such as Cannabis.

Auxins Encourage Rooting and Cytokinins Promote Cell Division

Auxins and cytokinins can be thought of as opposing additives and in general should not be used at the same time.

Rooting hormones (auxins) are commonly applied to cuttings to encourage them to develop roots and are often used in cloning female plants to propagate cuttings with the same gender as the 'mother' plant. Once the cutting has been taken, the powder, gel or liquid is applied to the stem end of the cutting before placing it into the chosen growth medium.

In nature, the auxin indoleacetic acid (also known as IAA or indole-3-acetic acid) plays a large role in root development, but it does not store well in solution. Thus, the more stable indolebutyric acid (IBA) and naphthaleneacetic acid (NAA) are often used in commercial products. These rooting hormones are auxins that are used to increase the auxin-to-cytokinin ratio, which stimulates root tip development at the expense of overall growth.

Cytokinins (CK) are plant hormones that promote cell division in growing shoots. Added to the soil or sprayed onto the plants, cytokinins help the plant to make efficient use of existing nutrients and water in drought conditions. Cytokinins will counteract the effects of auxins; a low ratio of auxins to cytokinins stimulates and promotes tip and shoot formation. Kelp and coconut milk are two sources of natural cytokinins.

Depending upon the ratio of auxins to cytokinins, the plant will emphasize either root development or shoot (leaf) development. Administering the proper additive at the proper time is the key to using these products effectively. Auxins are used to promote growth below the ground and cytokinins to promote above-ground development.