i'm afraid of my light. please help

[likespaphs]

hi there
so i used to grow in a great sunroom, then i moved and now i grow in a cold basement
a friend was nice enough to give me a 600 W hps (high pressure sodium) ballast so i went out and got a reflector and a way to hang now.
now my problem is how high should it be over the plants?
i think it's now about four, maybe four and a half feet above them, but i have the plants a good foot or three from directly under the light
to deal with the cold, i've put down a few heated propagation mats
i grow a mix of mostly multi, parvi, a couple brachy
thanks y'all

 

[Linus_Cello]

I would start further away, and slowly move the light closer to the plants. Stop or move the light further away if it appears that the plants are getting too much light. Maybe once the plants have gotten used to the light for several weeks, try moving it closer.

The multis will probably like more light, so have them closest to the light fixture (I think of them as almost like cattleyas in term of light requirement). Others further from the light.

 

[Justin]

just watch for yellowing leaves or burns and that will tell you if it is too close. how many hours is the light on?

 

[Paphluvr]

How cold is the "cold basement"?

 

[likespaphs]

they had been further away but i've slowly been moving them to where they are now
they seem okay without any yellowing
cold is cold (to me)
probably about 50°F, colder when it's cold outside
i have a fan running during the twelve hours (i think) i have the lights on
i have the prop mats set at 60°F

 

[Paphluvr]

I can't help you with your lighting issue because I've never grown under sodium vapor lamps but I am concerned about the temperature issue. 50deg (or lower) is pretty chilly and you don't mention whether that is a day or night temperature. Do you know if you have a temperature rise during the day when the lamps are on? Usually a change in day length as well a a difference in day and night temperatures initiates flower development. Taylor (and others) makes a nice min/max thermometer that would give you a better idea of what your actual day and night temps are.

Here is a link:http://www.taylorusa.com/catalogsearch/result/?q=thermometer+min+max

Have you considered tenting your plants in order to capture the heat from the mats and lamps? I've used a similar set-up to yours in the spring (with tenting) to start my garden seedlings (just not sodium vapor). A large plastic bag like a refrigerator or freezer might be shipped is excellent. It fit over a storage rack perfectly.

 

[Leo Schordje]

For high light plants, like vanda, Broughtonia, most Phrags and Paph philippinense, one to two feet is fine. I have some high light plants at about 2 feet from a 1000 watt HPS. For the more "average" Paph, 2 to 3 feet will be ideal. For the shade lovers the 4 foot distance is good. Somewhere around 5 feet will be deep shade.

The fan is critical to keep leaf temperatures down while the light is on. Slight air movement does wonders at cooling a leaf. But I would also leave the fan on 24 hours a day. In the cool of the night is when the bacterial and fungal problems progress, this is the second reason for keeping a fan on.

Your heat mats should be enough to keep the plants warm in a 50 ish growing area. The heat of the 600 watt lamp will be significant enough to give you a nice day-night temperature differential.

 

[likespaphs]

thanks folks.
i would like to have the fan run 24/7, but my gf is concerned it would be too hard on the fan. guess i'll have to get an haf fan
i haven't thought of tenting, but i'll look into it
thanks

 

[cnycharles]

Well you could either get really cheap fans and toss when they break or tough ones which are made to just 'run'


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