Overview

To define the optimal light intensity for the germination of cannabis seeds with the LED luminaire SANlight FLEX II 25, a practical test was set up and carried out in the internal laboratory. Seeds of the strain “Zombie Bride” were germinated in 77ér Eazy Plug trays. After germination, the plants were exposed to different light intensities; see Table 1 below.

Table 1: Number of FLEX II 25 with specification µmol

Over the following 39 days, it was observed how the plants developed under different light conditions. Various parameters, such as plant height, nodule spacing, and signs of stress, were documented. The experiment shows that the ideal exposure intensity for growing seed plants with the SANlight FLEX II 25 ranges from 160 – 200 µmol/m²s. Converted to an area of 1m², this corresponds to 105-140W / m² – when using the SANlight FLEX II luminaire. This optimal intensity and power were realized in the test using three or four SANlight FLEX II 25 per level of a CC trolley.

Recommendations

Four SANlight FLEX II 25 had the highest percentage of germinated and saleable seedlings. The advantage of this setup is the possibility to grow the plants under this light setup for a more extended period of time, as long as they are given enough space in the planes. The space limit was reached with 28 plants per level in 1.5L pots and 28 days of growth. It would need to be reduced to about 10-14 plants and one tier per CC cart removed to continue growing reasonably. After that, regular pruning in height and thinning of leaf mass is likely necessary to continue with this setup in the longer term. An example application would be micromothers.

The use of three SANlight FLEX II 25 can also be recommended. Here the percentage of plants with stress symptoms was below the setups with higher light intensity. It represents the famous “golden mean” and balances cost and performance. Even less experienced users will be OK with this setup.

Remark to the other setups

Using two SANlight FLEX II 25 can make sense under particular conditions. This setup may be appropriate when cost considerations are paramount, and longer seedlings with fewer nodes are acceptable. Plants under five SANlight FLEX II 25 have short nodal spacing, but the proportion of stressed plants increases. The margin for error is minimal, and any irregular growth will significantly affect the young plants. This setup should only be used when there is a great experience — the risk of breeding failures, high failure rates, and signs of plant stress increase. The higher purchase and operating costs should also be considered.