Walters Gardens TotalGrow Testing

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Irene Rosalyn Bennett
5 years ago
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1 Walters Gardens TotalGrow Testing Test Summary: The potential for a 2/3 power consumption reduction by replacing 1000W high pressure sodium lights with 150W TotalGrow TG15A lights was tested and proven by comparing growth characteristics of several Walters Gardens perennials. Eight characteristics were measured on 11 varieties of plants in 2 growth stages using 3 light intensities representing lesser, equivalent and greater than current Walters Gardens lighting levels. Plants tested: Monarda Leading Lady Plum (show and production, 3 light intensities) Echinacea Julia (show, 3 intensities) Heucherella (show, 3 intensities) Agave QWT (production, 3 intensities) Carex Banana Boat (production, 3 intensities) Coreopsis Moonbeam (production, 3 intensities) Coreopsis Zagreb (production, 3 intensities lost from inadequate watering) Dianthus Fire Star (production, 3 intensities) Geranium Rozanne (production, medium intensity) Echinacea Kims Knee High (production, medium intensity) Hakonechloa Aureola (production, medium intensity) Growth Data Collected: Height (all 10 varieties) Diameter (6 varieties) Largest leaf length & width (7 varieties) Branching (Monarda) Total shoots (6 varieties) Leaf Count (6 varieties) Root Score (all 10 varieties) Results Summary: The TotalGrow lighting strategy tested requires only one third of the power consumption of the 1000W HPS lighting system while consistently yielding statistically equal growth. Most variation in the data is better attributed to uncontrolled variables than to the lighting, especially differing soil moisture levels due to varying amounts of airflow and occasionally inconsistent watering. When combining data from all varieties, all traits were within one standard deviation of difference between lighting types with only height and branching differing by more than 0.5 standard deviations (greater in TG due to greater Monarda show plant sizes). Average light intensities were targeted at 25% higher under HPS to test the ability of the TotalGrow spectrum to be equally effective at a lower light intensity. Average light

2 intensities, measured in μmole*m 2*s 1 PAR, were 21% higher under HPS areas than TotalGrow areas when measured with an Ocean Optics USB2000 spectrometer and a mobile integrating sphere. Root growth and quality appeared to be the characteristic most strongly correlated with light intensity, showing improvement at higher intensities regardless of lighting type. Results in detail: Evaluating each data category by number of trials with greater values from each lighting type and average magnitude of variation, measured by standard deviations (SDs): Height TG greater in 16/29 trials (.6 SDs) o Greatest for TG in Monarda and Heucherella show plants and Agave and Geranium production plants, greatest for HPS in Coreopsis Moonbeam and Dianthus Diameter TG greater in 9/19 trials (.1 SDs) o Greatest for TG in Monarda, Echinacea and Heucherella show plants, greatest for HPS in Dianthus Largest leaf length and width TG greater in 10/18 trials (.2 SDs) o Greatest for TG in Monarda and Heucherella show plants, all others very similar Main Branches (Monarda show plants only) TG greater in 2/3 trials (.9 SDs) Total Shoots HPS greater in 13/20 trials (.3 SDs) o Greatest for HPS in Monarda production plants and Carex Leaf Count HPS greater in 12/17 trials (.1 SDs) o Greatest for TG in Monarda show plants, greatest for HPS in Monarda production plants and Echinacea Kims Knee High Root Score HPS greater in 16/29 trials (.3 SDs) o Greatest for HPS in Carex, Coreopsis Moonbeam and Echinacea Kims Knee High, all others very similar For each characteristic, there was a near split of trials with greater results between the two lighting types. Combined with the small magnitude of the average variations between treatments, these results strongly suggest that the lighting used was an insignificant source of variation. Focusing on lighting intensity, it was expected that the medium light intensity would produce the median value for each growth categories. In reality, medium light levels actually produced the smallest average numbers for half of the data categories in both lighting types. This is best explained by the greater impact of the other variables influencing growth. This medium lighting level is the most relevant, however, as it represents the amount of light currently provided in the greenhouses. Also, flats tested under medium light levels were most similarly positioned relative to fans and thus should have similar levels of moisture. Every plant also had at least one medium lighting treatment flat while 3 production plants did not have low or high intensity flats. Height, diameter, largest leaf length & width, leaf count, and Monarda s branching all were greater on average under TG lighting (0.5, 0.9, 0.5, 3.0 and 2.0 SDs of average difference, respectively) while total shoots and root score were a slightly greater under HPS (0.3 and 0.3 SDs of average difference, respectively).

3 Root data was also selectively analyzed. Root scores were determined by taking pictures of each plant s roots and giving a score between 0 5 relative to the other plants. This was thus the most subjective of the data categories taken. Especially dry or wet soil was noted as well as severity of bolting in flowering plants. Both lighting treatments produced the best results under high lighting with medium light slightly outperforming low light. Bolting had inconsistent effects. Wet and dry conditions appeared to adversely affect root development as well except for dry and normal conditions having equal results for HPS. Overall, HPS had a slight advantage in average roots scores. By observation, it appeared that TG plants occasionally had larger, whiter roots than HPS while HPS plants had a greater number of smaller, browner colored roots. Discussion: Plants grown under 1000W HPS and the effective equivalent amount of 150W TG15A lights did not demonstrate any consistent significant difference. Occasional variations within the small sample sizes of individual plant varieties and light intensities were better attributed to uncontrolled variables than to light source as they favored each light source relatively equally. For example, Monarda and Heucherella show plants under TotalGrow lights relatively consistently outscored HPS trials, but Dianthus and Carex plants under HPS lights showed similar trends over their TG equivalents. When combining all results, there appears to be a slight trend of TG plants having greater above ground growth and HPS plants having greater growth in roots and new shoots. This may be due to the radiant heat of HPS lights that dries out soil more quickly. The results should be drier soils under HPS plants than TG plants which would favor root development over above ground development. Growing under TG lights might allow reduced watering needs to maintain drier soils and better root growth when desired. Root growth also appeared to be the characteristic most directly improved by increased lighting intensities, especially under TG lighting. Average root scores improved by 0.6 (on a 0 5 scale) for both lighting types with the increase from low to high lighting intensity. It was the only category that increased both from low to medium intensity and medium to high intensity under both lighting types. Again, this may be confounded by increasing soil temperatures and dryness under increased lights, but represents an opportunity to refine growing strategies to improve root growth when that is a priority.

4 Figures: Figure 1 TotalGrow PAR output (μmole*m 2*s 1). Squares represent one square foot. Red areas represent lower than normal levels of equivalent supplemental lighting for Walters Gardens greenhouses, green represents normal ranges and yellow represents increased levels. Blue boxes show actual areas used for testing these light levels. Dark green areas are ideal test areas due to comparable air flow levels to dark green areas under HPS lighting (see figure 2). Thick outlines represent fixture locations ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## ## Figure 2 High Pressure Sodium output (μmole*m 2*s 1). Squares represent one square foot. Red areas represent lower than normal levels of equivalent supplemental lighting for Walters Gardens greenhouses, green represents normal ranges and yellow represents increased levels. Blue boxes show actual areas used for testing these light levels. Dark green areas are ideal test areas due to comparable air flow levels to dark green areas under TG lighting (see figure 1). Thick outlines represent fixture locations.

5 Averages (All Plants) TotalGrow HPS Figure 3 Normalized averages for the 8 measured categories of growth for all plants under each lighting treatment. Error bars represent one standard deviation greater or less Light Intensity Averages (All Plants) TG Low TG Med TG High HPS Low HPS Med HPS High Figure 4 Normalized averages for each growth category separated by both lighting type and light intensity. Error bars represent one standard deviation greater or less.

6 Figure 5 TotalGrow test area at the end of the test. Figure 6 TotalGrow finishing plants tests at week 1 and week 8.

7 Figure 7 TotalGrow production plants test at week 1 and week 8. More plant varieties were added as the test progressed.

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