4 Questions with Doug Jacobs

1. What are the most common issues that growers experience?

Stonewool has a much higher water holding capacity compared to other substrates, so the timing, frequency and volumes used to irrigate cuttings has a tremendous effect on how the plants develop. Watering too early is the biggest problem for most growers, so tray weight and individual plugs should be used in combination with plant observations, such as calluses and initial root formation, to determine the best time to apply first irrigations. Growers should experiment with different dry backs to determine the optimum per cultivar in their specific environment. It is also important to look at how much water is being applied after the first dry backs and work to find the optimum amount for developing the young cuttings.

2. What is a common misconception about starting plants in stonewool?

The most common misconception is the thought that because the cutting does not have roots, it does not need any nutrients. This is absolutely false. Starting out with too little or no nutrients when soaking stonewool starter cubes quickly leads to yellowing and weakening of the cuttings due to nutrient deficiencies. Even though the cuttings don’t have roots, it is still taking up some solution to maintain turgor pressure along with the humidity. It is best to apply nutrients from the very start of the cutting process at a concentration at least equal to or slightly lower than what the mother plant was receiving. 

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

The goal with precision irrigation is to provide the same amount of water and nutrition to every plant so they can grow at a uniform rate. Giving all the plants in an irrigation zone the same amount of solution allows for consistent quality and growth so the grower can deliver the same product time and again. The most common way to irrigate plants is through the use of pressure compensated drip emitters. Pressure compensated drip emitters provide a consistent drip of water to each plant, allowing them to grow at the same rate. The use of unregulated drip emitter delivers different amounts of water to each plant, creating inconsistencies in plant growth and quality. The use of flood and drain tables or trays is also a good way to make sure all the plants in the irrigation zone receive the same amount of water. 

4. How does using a proper growing medium streamline operational efficiency? 

Setting up a new crop and cleaning after harvest usually involves a lot of labor: moving growing media and plants in and out, cleaning containers, mixing substrates, packing containers, and transplanting. To maintain an efficient and cost-effective growing operation, these tasks should be minimized. Growing media, given their volume and weight, can be a huge factor in setup and removal labor requirements. Cleanliness can also be difficult and expensive to maintain with dusty loose substrate, so when selecting a growing substrate, you should look for one that is clean, self-contained, lightweight and allows for increasing speed of setup, transplanting, and disposal, all while reducing labor to a minimum.