End consumers of plug plants [myself included] love the ease with which they can be planted directly outdoors, minimizing time to maturity and maximizing gardening success. What many do not know is that the shape, robustness, and future health of plant plugs can be controlled by the light spectrum under which they are grown.

by Rebecca Knight, Illumitex

Horticulture lighting research has been conducted on young plants (germination, seedlings, plugs and cuttings) for many years. Michigan State University published a series of articles in Greenhouse Grower (see references below) on bedding plant seedlings. In their research, Drs. Wollaeger and Runkle experimented with different LED wavelengths and compared them to fluorescent light on seedling height and leaf area of tomato, salvia, petunia, and impatiens.

Another study, published in GPN (Greenhouse Product News) and conducted at Purdue University, compared the effects of supplemental and sole-source lighting for LED, HPS and plasma sources on the plug quality and flowering time of petunia and geranium. In their study, they used two LED spectrums with different percentage of blue and red.

In one of our Illumitex in-house experiments, we compared the effects of two spectrums (F3 and F6) on plant diameter and root length, two important parameters in bedding plant seedlings. In the photo below I am looking at the F3 treatment with the F6 treatment above – all treatments received the same light intensity.

Read more at the Illumitex blog