You may notice moisture scale of 1 to 5 in most of the growing guides that we have shared and always wondered what they meant. Here, we have a pictorial guidelines to show you what each level means.
Using a standardized approach to evaluate substrate moisture levels can greatly improve the performance and consistency of a young plant operation. Develop a common language of 'wet' and 'dry' to improve communication between employees in different greenhouse sections. The Moisture Scale is used by many plug and liner growers as a key part of their irrigation management.
The 1 to 5 Moisture Scale
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Moisture level 5 – Saturated The substrate is completely saturated and appears shiny and black in color. Free moisture can be seen at the substrate surface and dripping from underneath cells. Trays may bend under the heavy weight of the water. In your hand, moisture drips from substrate without squeezing.
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| Moisture level 4 – Wet The substrate is at maximum water holding capacity and appears dark. It is not shiny, and no free moisture is visible at surfaces. The tray may still bend under the water weight. Lightly pressing down on the substrate will force water from underneath the cells. Squeezing the substrate will quickly release moisture from your hand. After squeezing, the substrate will retain its shape. |
| Moisture level 3 - Medium The substrate is drying due to plant uptake and evaporation. The substrate appears brown in color and is lighter in weight. Strongly squeezing or pressing the substrate only releases a few water droplets. After squeezing in your hand, the substrate begins to crack apart into chunks.
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Moisture level 2 – Medium Dry The substrate appears light brown to tan and has become light in weight. Most rooted crops irrigated at this stage. Plants may begin to wilt. Squeezing the substrate as hard as possible releases no water droplets. If you squeeze the substrate next to your ear you can hear sounds of moisture moving through pore spaces. After squeezing, the substrate is loose and falls apart in your hand. |
| Moisture level 1 – Dry Completely dried and tan to grey. No water is available and the substrate is very light weight. Many plants may not recover if wilted to this stage. Substrate may separate away from tray cell walls. Squeezing the substrate as hard as possible will not release any water droplets, and when squeezing next to your ear you cannot hear moisture moving through pore spaces. After squeezing, the substrate crumbles in your hand and resembles dust. |
