Stonewool and Microgreens

Posted on August 28, 2020 by Red Rock Block

Using Stonewool to Grow MicroGreens

Microgreens and Stonewool: Growing Tiny on a Large-Scale

 Stonewool is a popular option for commercial hydroponic growers across the world in all types of applications and plant types. With its origins in the construction industry, this material has proven itself in being an excellent growing media for horticulture applications. With the rugged nature and ability to keep up in the intense environment of high heat and water of the commercial greenhouse. Many other options available to the commercial grower wear down over the growing season and in some instances can create clogs or wear on the actual hydroponic system.

What is Stonewool?

Stonewool is also referred to as mineral wool and is one of the most widely used and popular media in the commercial hydroponic industry.  Not only can this material be used in the commercial industry, it is also a great media for the small scale grower. This material wasn’t always used for growing plants. In fact, this material has origins in the construction industry with insulation applications. When basaltic rock was melted and spun into thin fibers and wrapped into sheets, builders found that the insulating properties of the material were excellent for all buildings. Then in the 1960’s Denmark researchers conducted studies on the ability of stone wool to support crop growth. After these studies, stone wool was further developed and engineered to support plant growth even better! Now it is one of the top media to grow plants no matter the scale.

What are Microgreens? 

Microgreens are plants that are very basic in nature having three distinct parts- a central stem, cotyledon leaf or leaves, and the first set of true leaves. Microgreens will vary in size from 1-1.5in in total height or length. When the microgreens get beyond this measurement, they gain the label petite greens. Microgreen crop times are very quick with harvest typically occurring in 10-14 days from seeding to harvest. There are slower varieties of microgreens such as chard, beets,and other herbs that take 16-25 days. There are many different labels for microgreens that stem from the stage of growth the crop is harvested. With this quick turnaround time, stone wool can be the ultimate solution for growing media as it is designed to withstand traditional crop grow times.

Advantages of Growing Microgreens in Stonewool

There are several advantages of stonewool that set it apart from other forms of growing media. This substrate is very easy and convenient to use meaning that growers start growing their crops in stonewool right away. Stonewool is a sterile and clean media naturally meaning there is a minimal risk of pathogen contamination of crops. This grow media is also made with the most ideal structure and thickness while still being lightweight and easy to handle. With a smooth surface, even the smallest of seeds can be sown evenly with ease. With its thickness, the media is also the perfect substrate for microgreens to grow in without wasting materials. Stonewool is also known for its reliability and water management ability to maintain proper moisture levels without starving or drowning plants. Last,but not least, this material is affordable with overall cost lower than other forms of media such as biostrate, coco coir, and hemp mats.

Supplies Needed for Microgreen Production with Stonewool

It is important when preparing for a growing season no matter how short, to have the right setup and materials to start off on the right root. In order to fully maximize space and fully get the maximization of space in the commercial operation, racks and an automatic system should be installed to vertically grow microgreens.  This process uses a reservoir and water pump to supply the system with water and nutrients to all levels of the vertical system with lights located at every level. Below is a list of suggested materials and supplies needed for the production of microgreens in a hydroponic system using stonewool.

Supply Description
Growing Trays Trays should be those with drainage holes and with the standard size of 10”X20” is the most common.
Microgreen Seeds Be sure to research the seeds and select the varieties and species that are right for the operation
Lights Lighting in a greenhouse is important with T5 lamps preferred by most growers. However, LED lighting is suited best for vertical farming as lights can be placed close to the plants without damaging tissue.
Growing Media Although other media such as coco coir and hemp mats can be used, stonewool has shown to be best for the hydroponic system as clogs and breakdown of material is lower and virtually nonexistent.
pH Test Strips or Kits When working with stonewool, it is at first very alkaline and will need rinsed and monitored before plants are sown. Frequent water pH tests should be conducted no matter the type of crop grown for a hydroponic system.
Plant Nutrients Proper water soluble fertilizer and nutrients are best for a hydroponic system as they will not clog the lines
Hydroponic Reservoir and Pump To keep the water flowing on a continuous or timed cycle, the system will need a large water reservoir with a pump to distribute the material evenly.

Depending on the operation, there may be fewer or more supplies needed to meet the overall needs of the operation. Proper research and feedback should be done before the growing season.

The answer to the question of if stone wool is the right material for microgreens depends solely on the priorities, goals, budget, and overall needs of the operation. With benefits ranging from ease of use, durability, sterile media, and more stonewool has proven to be ideal for most types of grow ops in the commercial horticulture industry.

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