## 1 Introduction  
The large strawberry production industry in the USA is composed of approximately 52,700 acres [1] at an approximate density of 21,780 plants per acre [2]. Since the propagation of strawberries is mainly vegetative, the USA industry requires a vast number of cloned plants, such as bare roots and plugs, to meet the geographical and seasonal demand. In order to have enough planting material (daughter plants) to supply fruit growers, propagators have to carefully coordinate the reproduction of strawberry stock plants for several years and in multiple geographical locations (USA and Canada). The current field propagation system is vulnerable to several problems including a decrease in plant quality after long storage, low availability of planting material, and high risk of pathogen transmission from the nursery to the production field. For example, anthracose has been identified as a typical nursery transmitted disease that remains symptomless during propagation; however, devastating symptoms appear late in the fruit production season [3]. \"Albion\" strawberry plants became popular in Southeastern United States for extended season production. Albion is commonly classified as a \"day-neutral\" (everbearing) flowering plant since it is capable of flowering under both long-day and short-day light conditions [4]. Recent research has shown that Albion shows a facultative long-day response where flowers initiate faster under long-day condition [4]. Albion and other day-neutral cultivars often produce low numbers of daughter plants in open-field propagation systems [5]. Asexually propagating strawberry plants in a controlled environment using precise environmental strategies (precision indoor propagation, PIP) could address some of the challenges of open-field strawberry propagation. For example, environmental conditions can be controlled to initiate or prevent plant flowering [6], improve plant morphology (compactness and extension) [7], and maintain higher consistency of plant quality (uniformity) [8], among others. In addition, PIP systems have higher protection from the inoculum of outside pest or pathogens. Research has demonstrated the potential of indoor systems to propagate several crops including snapdragon [9], petunia, impatiens, salvia [10], tomato [10; 11], cabbage [12], grape [13], cucumber [14; 15], and stevia [16], among others. One of the main challenges for the adoption of indoor growing systems such as PIP is the high energy demand driven by the use of electrical lighting for photosynthesis. Therefore, research studies in other crops have focused on optimizing the use of light in indoor production systems, for example, adjusting the photoperiod for leafy green production [17] and increasing CO\({}_{2}\) concentration to increase photosynthesis under lower light intensity [18]. In order to make PIP systems more affordable for the propagation of strawberries, it is imperative to find the optimal light intensity to increase the number of daughter plants produced and to decrease energy consumption. Few studies have focused on light intensity for strawberry propagation. In one study, \"Toyonok\" (short-day) strawberry plants were grown for stolon production under different light sources and spectrums [19]. Results showed that 110 to 122 umol m\({}^{-2}\) s\({}^{-1}\) photosynthetic photon flux density (PPFD) provided by white fluorescent lamps (5000 and 6500 K color temperature) promoted both stock-plant growth and formation of daughter plants as compared with plants under 50 to 55 umol m\({}^{-2}\) s\({}^{-1}\) provided by fluorescent lamps with warmer color temperature (4000 and 3000 K) [19]. Light emitting diodes (LEDs) of different colors have been examined as the light source for strawberry propagation. For example, plants in 30% blue/70% red photon flux density (30B:70R) treatment produced the highest total number of stolons, whereas, in 20% blue/10% green/70% red (20B:10G:70R) treatment, plants had the highest daughter plants per stolon [20].