Color temperature to get Vandas to bloom

[W Stender]

Hello all! Well I have two vandas (with tight V terrete leaves) that are otherwise very healthy and happy except I have a very difficult time getting them to bloom. They were out all summer in full sun and finally got one of the two to bloom (yeah!). Now I am bringing them into a south facing greenhouse that gets 3/4 day sun (the suns sets behind trees in the PM) I am thinking about augmenting the ammount of light with (2) 2' t-5 bulbs hung above these two plants for a 14-16 hour duration. I do not know if I shold use 6500k or 3000k T-5 bulbs or a combination of one of each. Any comments?

[Ray]

6500°K has a spectrum closer to natural sunlight on a summer day, but intensity may be more of an issue. Terete-leaved plants need a LOT of light. 2 x 2' T5 will give you about 48W, while single 4' T5 is 54W.

[W Stender]

You have a good point, but the two 2' fixtures will more efficiently place light over the two vandas, which hang in less than 2' of space on one of my hanging rods on the south side of the greenhouse. So a 2' fixture with two 2' bulbs will apply light more efficiently. Any opinion about whether a 3000K bulb could promote blooming better than a 6500K?

[neb]

The 3000K is redder and should help but if you are concerned about stimulating blooms then a HPS light is what you may want to ask about.

[W Stender]

I thought the common direction everyone was going toward was fluorescent? I am concerned a HPS would add more heat than I woud like to my already warm greenhouse.

[johnblagg]

actually 100 watts of hps is not going to add that much heat if you go with a smaller size light or 70 watt for that matter wats are wats and t5s put out a good bit of heat too.....the most effiecient lights are hps or mh actually, flouresent are just easier to mount and get into tight places compared to hid lights.
Everyone thinks flouresencts are the most efficent for some reason when actually the 600 watt hid light from what I have read are the most bang for the buck...and in my experiance as well having used both.It is space issues that make t5s great for under shelves ect....and reflector issues as well

[kavanaru]

As John said, spave saving is the trigger for fluorescent tuve (IMO)

as per the light temp, I would go for that being more similar to daylight... your plants need also othetr light temps to grow healthy and only blooming buster would not provide a healthy plants!

My experience, and I had good plants (healthy and blooming regularly) growing under T5 tubes (now they moved to a greenhouse), is that combining different tubes provides the best results, as it imitates better dayplight (Daylight tubes normally miss some parts of the daylight spectrum, but to the human eye they look pretty much like "daylight").

My recipe: a proportion of 2:1 (6500° : 3000°)

[CALLY]

Hi, Quick question:

would 2500K be redder than 3000k.
Would 2x 6500K and one 2500k be adequate?

Thanks

[Connie Star]

Originally Posted by CALLY

Hi, Quick question:

would 2500K be redder than 3000k.
Would 2x 6500K and one 2500k be adequate?

Thanks

Yes, 2500K would be redder than 3000k

[Ray]

6500°K give toy about the same relative concentrations as the sun of the right wavelengths for photosynthesis. By my thinking, with sufficient intensity of that spectrum, proper nutrition, watering, and temperatures, your plant will be as healthy as it can be and will bloom to its maximum capability. Adding more light on one end of the spectrum is not likely to improve upon that.

Let me add that three 2-foot, high output T5's are giving me about 1500-1800 foot candles at a distance of about one foot from plants in my terrarium. Two of those bulbs will put out about 4000 fc at 1" distance, and vandas are known for taking a lot of light, even more than the two bulbs could handle.