Indoor HPS light too much?

[Kurruptklown]

Was wondering if my 600w HPS light is too much for my new autos that just popped?? I have a light gauge and its not as bright as being outside so I thought they should be ok. Temp is around 80, I have fans blowing in cool aire and pushing out hot hoy from the light, just want to make sure I'm ok?

 

[mr.mcgregor]

keep the lights higher than normal and lower them over a week or so. 600w directly above seedlings can be a bit intense for them. if they look like there streching just lower the light a bit more.

this is what i did before getting a dimable ballast.

 

[Kurruptklown]

i have a dimable ballast but also are growing other plants that are further along

 

[mr.mcgregor]

how big aare the other plants? the lamp might be high enough above the seedlings anyway.

 

[Kurruptklown]

i can adjust the lights any height I want, just want to know how much light that young of a plant should be getting???

 

[BigBuddha]

Hi Kurrup,


It's difficult to say with any accuracy "how much" light they should be getting beyond the minimum. Many strains are more heat-resistant than the next, to, so one may do better than another.

All those contributing factors tend to lead growers to not use HID's at all for seedlings. I didn't for a long time and spent a good chunk of cash on a germing tent etc... only to find later on that my seedlings seem to be able to handle the HID's.

As Mr M says.. there's a sweet spot between the light being too close and too far away. Too close = oven time.. too far = stretching. For me that distance is *roughly* 36" with a 600w MH bulb, but I really don't know for sure if that IS the sweet spot, or just an 'OK' spot.

That aside.. if it's a pure HPS bulb, one thing worth bearing in mind is that some growers (not all) notice some plant health problems under pure HPS bulbs due to the lack of blue spectrum in it (they need that for vegging mostly). Some others do perfectly well with them start>finish so it's not like they can't be grown under pure HPS.. cos they can and are. It's just something to add to your list of possible contributors if you get any early problems. Lack of blue spec also increases stretching according to the science books but, again, you'll find many growers who say that simply isn't the case in their grooms.

The other main consideration is that if they're in small pots they'll dry-out very quickly under a HID, and I've seen (and been the victim of) younglings being baked in a matter of hours sometimes, so it's good to keep on top of that.

There is a school-of-thought (even scientifically supported) that says that HID's are too light-intensive for younglings and can damage their stomates on the leaves.. but personally I've not noticed that if it's the case or not because mine seem to do pretty well under HID's. I can't really get my head around it because seedlings manage perfectly well in bright sunlight so common-sense says they'll be ok under a HID in that respect.

 

[Kurruptklown]

Hi Kurrup,


It's difficult to say with any accuracy "how much" light they should be getting beyond the minimum. Many strains are more heat-resistant than the next, to, so one may do better than another.

All those contributing factors tend to lead growers to not use HID's at all for seedlings. I didn't for a long time and spent a good chunk of cash on a germing tent etc... only to find later on that my seedlings seem to be able to handle the HID's.

As Mr M says.. there's a sweet spot between the light being too close and too far away. Too close = oven time.. too far = stretching. For me that distance is *roughly* 36" with a 600w MH bulb, but I really don't know for sure if that IS the sweet spot, or just an 'OK' spot.

That aside.. if it's a pure HPS bulb, one thing worth bearing in mind is that some growers (not all) notice some plant health problems under pure HPS bulbs due to the lack of blue spectrum in it (they need that for vegging mostly). Some others do perfectly well with them start>finish so it's not like they can't be grown under pure HPS.. cos they can and are. It's just something to add to your list of possible contributors if you get any early problems. Lack of blue spec also increases stretching according to the science books but, again, you'll find many growers who say that simply isn't the case in their grooms.

The other main consideration is that if they're in small pots they'll dry-out very quickly under a HID, and I've seen (and been the victim of) younglings being baked in a matter of hours sometimes, so it's good to keep on top of that.

There is a school-of-thought (even scientifically supported) that says that HID's are too light-intensive for younglings and can damage their stomates on the leaves.. but personally I've not noticed that if it's the case or not because mine seem to do pretty well under HID's. I can't really get my head around it because seedlings manage perfectly well in bright sunlight so common-sense says they'll be ok under a HID in that respect.

great info!!! I have 2 under 26 watt 6500k CFL bulbs and the other auto under the 600w hps with my pepper plants, all 3 seem to be doing just fine. I have noticed that all the plants under the hps do seem to dry that soil out very quickly, so I find myself just rewetting the surface alittle. That was my thinking on why can't they grow under hps if they grow under sunlight??

 

[BigBuddha]

In my experience, virtually always, the problem growers have with HID's and seedlings has been because of the pots drying out too quickly and them not taking that into account. It can literally take hours so you put them under it at 9am and by the time you come home from work at 6 they're baked! One of the old growing legends turned into general advice, which is that there's no point putting seedligns under HID's because you have to raise them so much it's inefficient. And it is, because plants can only absorb so much light before the rest is wasted. But if you have older plants under it too, it isn't inneficient cos you just put your seedlings lower than the canopy.

In my opinion there is a sweet spot for HID's/seedlings, and once you find it you can put all your seedlings in the main area without an issue, but it depends on your total environment, strain, size of pots etc etc.

As you say, you're not seeing any issues compared to the ones under CFL's.. so I'd say that you've found the spot or got close already.