How to Properly Rehydrate Unrooted Cuttings
February 12, 2026 In a recent e-Gro Alert, Dr. Roberto Lopez of Michigan State University outlines how to create an organized, uniform system to properly rehydrate unrooted cuttings (URCs). For any operation or individual looking to create their own system or incorporate aspects into an existing one, here’s what Lopez suggests.
What Dehydration Does to Cuttings
According to Lopez, water loss has immediate consequences for URCs. Because these cuttings lack roots, “they rely almost entirely on stored water and limited foliar uptake to maintain turgor.” Therefore, when dehydration occurs in URCs, “leaf tissues lose turgidity, stomatal function becomes erratic, and processes associated with wound healing and callus formation slow dramatically.” Even with cuttings that can visually recover through misting, there can be “internal water deficits” that result in weak, damaged tissue and a reduced chance of rooting.
Inspecting for Dehydration Symptoms Upon Arrival
Once arrived, “cuttings should be inspected immediately rather than left sealed in shipping boxes or bags.” Visual indicators of dehydration include:
- Brittle tissue
- Limp stems
- Wilted leaves
All of which suggests water loss. However, Lopez notes that a “tactile assessment is equally important,” with properly hydrated cuttings maintaining firmness, compared to dehydrated cuttings breaking and bending under light pressure.
Lopez stresses the importance of temperature management during shipping to avoid the dehydration of URCs. The employment of coolers helps to “reduce metabolic demand (respiration)” but also creates low-humidity environments that accelerate moisture loss. Therefore, refrigeration is not, in and of itself, a solution, with the need for maintaining high humidity being paramount. Additionally, while “the ideal temperature to store the vast majority of URCs is between 50 to 55˚F,” the type of plant must be considered, as the effects of dehydration aren’t uniform across plant species.
Basics and Best Rehydration Practices
Lopez notes that “rehydration strategies vary widely among commercial operations, but they can be broadly categorized by their effectiveness and level of environmental control.” Misting is the most basic method, due to its simplicity and low cost. However, the large droplets produced by misting systems drop at high speeds, often “wetting the substrate more than the URC.” Additionally, misting fails to account for many internal dehydration effects and runs the risk of spreading diseases with overuse.
Another popular, but more labor-intensive, method is that of dipping cuttings. This is far more effective than misting, but, in addition to the added labor, dipping cuttings also require more strict sanitation practices for disease control. Lastly, there’s a short time window between dipping and sticking to maintain moisture levels.
One final option Lopez covers is that of fogging systems, which he believes represent “the most effective and consistent method for rehydrating unrooted cuttings.” Compared to misting, the droplets produced by fog are extremely small and “remain suspended in air,” helping to maximize “leaf-surface contact” and “promoting gradual foliar water uptake” without flooding the growing media.
For additional information on rehydrating unrooted cuttings, including controlling for vapor pressure deficit (VPD) during root development and how different plant species are more susceptible to dehydration, please read the full e-Gro (Electronic Grower Resources Online) alert “Rehydrating Unrooted Cuttings: A Systems Approach to Uniform Liners.” Additional and current e-Gro alert pieces from Volume 15 (2026) can be found online.
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