5 Questions with Pierre-Marc de Champlain

Special Advertising Section - Special Advertising Section | Ask the experts: Growing Media

Pierre-Marc de Champlain, director of technical services for Berger, explains how to select the right growing media for your cannabis cultivation operation.

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July 2, 2019

1. What type of growing media should be used for cannabis production?

Ideally, you want to use a substrate that will provide excellent drainage. This allows you to implement a more precise fertilization strategy, making it easier to steer the crop through its different growth stages and maximize yield. A high-porosity mix with coarse peat and perlite (e.g., Berger BM6 HP) is a dependable choice that provides air space for healthy roots.

A coarse peat and wood fiber growing media (e.g., Berger BM4 NF Wood HP) can also be used and provides good porosity with a slightly superior water reserve, which can be very beneficial during summer productions. This combination is excellent for rapid root development, as long as the irrigation practices are adjusted adequately. By using a peat and wood fiber growing media made with 100-percent biodegradable materials, it is much easier to dispose of the used mix.

2. What attributes are important when selecting growing media?

Weather conditions, greenhouse infrastructure, container dimensions and irrigation strategy are all important aspects, but one not to overlook is the growing media’s quality and consistency. If the chemical or physical characteristics vary significantly from one container to another, it becomes very difficult to manage irrigation and fertilization timing. This can have a major effect on growth uniformity and reduce the final yield.

3. What about coir?

Selecting the correct grade of coir is critical. A combination of coir chips and regular grade coir provides an excellent soil structure. However, quality is key. If the coir isn’t conditioned properly, serious salt damage can occur, and potassium may be massively released during the initial fertilization events. The particle size can also be variable.

Make sure you buy coir from a reputable producer and test the electrical conductivity (EC) prior to planting. A safer bet is to use a combination of coarse peat moss and coir chips, two components that complement each other very well.

4. Can the same growing media be used to germinate seeds or root cuttings (clones)?

Yes, but this is not ideal. For seed germination, you need a substrate that will provide sufficient moisture around the seed. If the substrate is too porous, the germination process can be affected; some seedlings may emerge faster than others, the primary root could have trouble penetrating the substrate, and the germination rate can be lower. I recommend using a substrate with a finer grade of peat moss, perlite and vermiculite (e.g., Berger BM2).

When selecting the appropriate growing media to root cuttings, the same principles apply: Maintain sufficient moisture to stimulate the initiation of the root nodes. You can also use a slightly more porous growing media, especially if you are using a large cavity tray or paper pot.

5. Should I consider making my own mix?

Many intangible elements of making your own mix can be overlooked, leading to unforeseen additional costs. Everything must be considered, including machinery, ingredients, labor, additives and quality control. Mistakes made during the mix production process can lead to significant crop losses. Purchasing a high-quality, ready-to-use growing media from a reputable soil manufacturer guarantees that the physical and chemical characteristics will be consistent. They offer many different substrate options and can also customize your formulation to cater to your needs.