Not only must you select a growing media that will be the best fit for your plants, but you also can optimize its use in cannabis production with tips from Grodan Technical Advisor Doug Jacobs.

1. Why is substrate volume important?

The right substrate volume allows for correct irrigation start and stop times and proper dry back during the night. The right volume also allows for the right balance between stable electrical conductivity (EC) and being responsive when the nutrient needs refreshing. Oversizing your substrate increases cost and will delay plant growth, as it takes longer for a young plant to develop root volume. Under-sizing the substrate volume can cause rapid changes in water content and EC, giving less stability for the roots, and may result in unnecessary additional irrigations, which may lead to a reduced yield. Additionally, choosing a substrate volume that is too low will restrict the root volume, and that will limit plant growth and the length of the cropping cycle. When deciding on growing substrate volume, consider the plant’s growing cycle, how reliable and accurate your irrigation system is and how your environment might impact transpiration.

2. How does the use of the proper growing medium streamline operational efficiency?

Setting up a new crop and cleaning after harvest requires labor, including moving growing media and plants, cleaning containers, mixing substrates, packing containers and transplanting. To maintain efficient and cost-effective operation, these tasks should be minimized. The volume and weight of growing media can be a huge factor in setup and removal labor requirements. Cleanliness also can be difficult and expensive to maintain with dusty, loose substrate. Look for specific criteria when selecting a growing substrate including clean, self-contained, lightweight, which allows for increasing speed of setup, transplanting and disposal, while reducing labor to a minimum.

3. What is the correct way to irrigate my plants in Grodan?

The most common way to irrigate plants in growing media is with pressure-compensated drip emitters that provide a consistent drip of water to each plant, so they grow uniformly. The use of an unregulated drip emitter delivers different amounts of water to each plant, creating quality and growth inconsistency. The use of flood and drain tables or trays also allows all plants in an irrigation zone to receive the same amount of water.

4. How can I use my irrigation strategy to get the most out of my plants?

When applied correctly, irrigation can be used as a tool to manipulate plant growth to maintain the correct plant balance throughout the cropping cycle. By changing irrigation volumes, frequency, start and stop times, the grower can control and steer the water content and EC in the substrate during the day, but also maintain root health and plant balance. Adjusting irrigation start/stop times, volumes and frequency. It allows the grower to steer the plant between vegetative and generative growth.

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