Cattleya Heathii and LED lighting

[terryros]

This is Cattleya Heathii, a primary hybrid of C. loddigesii and C. walkeriana, two Brazilian species that naturally grow close enough together that their natural hybrid was also discovered and called Cattleya x dolosa. Cattleya Heathii was registered in 1907 by Heath.

C. walkeriana is a compact species with the unique trait of blooming from a separate growth from the rhizome while C. loddigessii grows about a foot tall and blooms from the apex of the pseudobulb like almost all other Cattleyas. Most Cattleya Heathii, including this one, resemble loddigessii in growth habit and bloom from the apex of the pseudobulb.

Depending on the varieties of walkeriana and loddigessii used, Heathii can vary from white to darker pink/purple. The bud development of this plant during the last month occurred with day temperatures averaging about 68 F with night temperatures of 58 F. There is only faint, pleasant fragrance with this bloom, unlike the two C. walkerianas that I have bloomed that have had stronger fragrance in the morning.

This plant was purchased from Orchids Limited about a year ago and was transferred immediately to a Rand Air Cone pot in a mix that was about 50% GrowStone and 50% milled sphagnum moss. It was grown exclusively under ALT PAR 30, 15 watt natural white LEDs with 60 degree lenses. The bulbs are listed as producing about 1050 lumens each and are about 14 inches over the top of the leaves. Using an Apogee hand-held PAR meter, 150 micromoles/m2/sec were delivered to the top of the leaves. Using a lux/footcandle meter the light intensity measures about 1,500-1,600 footcandles.

The plant received peak day length of 14 hours in the summer and the sheathless spike appeared in about September as the day length in the plant room was gradually shortening to a low this last month of 11 hours. This amount of PAR would not traditionally have been thought of as high, but the blooming growth was bifoliate with purple coloration in the proximal leaves, compared to the previous five growths on the plant that were unifolate and uniformly green, indicating very good light for this new growth.