Sowing seeds under HPS

[Batboy]

I am using Mother Nature's method of germination: plant in soil, spray with distilled water and cover with plastic wrap. Originally I was using 2 42w CFLs for warmth and the seedling stage, but IMO the CFLs just weren't warm enough for germination -- granted I didn't wait more than 36 hours before deciding this, but the temps at the top of soil never went over 72F at 24/0. At this point I'm not buying a heating pad, so light(s) will have to generate the warmth.

I ditched the CFLs, turned on my 400w HPS and now I've got more than enough warmth, but I'm worried. Temps at soil lever are now 80F and the light is 32" away. 2 of my 5 seeds have broken through the soil at 3 1/2 days so they are now uncovered. I'm concerned that the HPS might be too much for them.

At what distance is a 400w HPS safe for delicate seedlings? Should I shade them or keep them in direct light? Once all seeds have broken through (or been given up on), should I switch back to CFL?

 

[Irie_Lion]

i keep mine about 12-16" away once i see the first lil set of round leaves and gradually move closer each day til they are bout 4-6" away...is your light air cooled? if not just keep a fan blowing the heat away from the lamp and u should be ok...and yea if u want to save some energy keep them under the cfls for a few days and then move'em back all a matter of preference imo

 

[MobbDeep]

IMHO..thats a good way to germ seeds..what I sometimes do is fill a Styrofoam or solo cup with a STERILE inert medium,such as coco coir..soak seeds in cup of water for around 5 hours,then place seeds 1.4 inch into medium..then I cover the seeds with Glad cling wrap..this keeps the top medium from drying out,which can kill the fragile seedlings,and it keep the soil nice and warm..then I place under the 400 hps immediately..

Keep 400 hps as far or as close as you can,the only thing thats stopping you is the temps..so as long as the temps are cool,then you can place the hps around 12-18in...

There is no such thing as too much light,remember all plants have sprouted for millions of years under the very powerful sun..and a 400 hps is not NEARLY that strong..the main thing you have to worry about with delicate plants is to keep them cool,and well hydrated,and focurse,planety of air movement..heat+dry=ead wilted plants

I started my seedlings under the hps,and they never had a problem..
There is no such thing as too much light for seedlings

The whole thing with "hardening" teh plants to either the outside sun or a h.i.d is when the seedlings are started under a low wattage fluro light..cus you are "tricking" the seedlings that the sun is the low power fluro..and they become used to it..so when you move to higher intensity,the plants have to get used to that,.but if you start udner the high power light,theyr aleady used to it,so theres no need for hardening off..

 

[Batboy]

Thanks for the replies. I was just a little nervous that the fledgling seedlings would get hit by that powerful light and shrivel up and die. I'm probably over thinking things because I have nothing else to do but stare at dirt.

The light is air cooled and I've got solid negative pressure in the cab, so the passive intakes are providing nice circulation, even without me adding a small oscillating fan which will come later.

I guess what you guys are saying is that with a decent airflow and a temp of 80F (I could cool it down more, my inline is only running at 25%, but I thought 80F was good for popping those seeds), there is no need to shade or otherwise protect the new seedlings from the HPS?

 

[Irie_Lion]

Thanks for the replies. I was just a little nervous that the fledgling seedlings would get hit by that powerful light and shrivel up and die. I'm probably over thinking things because I have nothing else to do but stare at dirt.

The light is air cooled and I've got solid negative pressure in the cab, so the passive intakes are providing nice circulation, even without me adding a small oscillating fan which will come later.

I guess what you guys are saying is that with a decent airflow and a temp of 80F (I could cool it down more, my inline is only running at 25%, but I thought 80F was good for popping those seeds), there is no need to shade or otherwise protect the new seedlings from the HPS?

Nope u r good bro

 

[Hank Hemp]

Tough Luv

Tough Luv

Your main problem is you are watching them to closely. Leave them alone or you will love those babies to death now. If you cannot help yourself give them a quarter turn each day, that will help you to leave them alone.

 

[MobbDeep]

You good to go,although once the seedling pop..if you can lower the temps to around 75-78f..thatll be better than 80..if not its fine..also try to get a small osccilating fan in there to move the seedlings around a lil..this will strengthen there stems so they dont become too leggy..

 

[Noobian]

I remember reading somewhere that seedlings grown exclusively under an HPS spectrum have a higher chance of turning male than seedlings grown under a mixed spectrum or 6500K lighting exclusively. Something about how the lower red light wavelength triggers a higher percentage of male hormones to activate in the third or fourth weeks of the plants life or something like that. I don't know how accurate that article was but its something to think about I guess since you are using your HPS for vegging as well as flowering. Does anybody else know anything about this?

 

[Batboy]

Your main problem is you are watching them to closely. Leave them alone or you will love those babies to death now.

So true. During my first grow, I promised my wife as the grow progressed that I wouldn't need to spend so much time with the plants once I got the hang of it. I found that I preferred tweaking, tinkering and mothering my plants at night much more than watching crap on TV. This is my second grow and I can tell that I am going to have to sit on my hands and let nature do the driving. At least I'm at work about 10 hours a day so I can't fuck with them then.

I remember reading somewhere that seedlings grown exclusively under an HPS spectrum have a higher chance of turning male than seedlings grown under a mixed spectrum or 6500K lighting exclusively. Something about how the lower red light wavelength triggers a higher percentage of male hormones to activate in the third or fourth weeks of the plants life or something like that. I don't know how accurate that article was but its something to think about I guess since you are using your HPS for vegging as well as flowering. Does anybody else know anything about this?

That's interesting. I wonder if anyone has the backup for this. 2 (possibly 3) of my 5 seeds are fem, so I'm not too worried.

 

[MobbDeep]

its kinda true..ill give you some tips for better female ratios

1.try the banana method for a week with the seeds

2.start seeds and veg under a blue spectrum light 6500k

3.higher nitrogen in veg promotes more females

4.shorter light cycle (18-6...16/) makes more females

5.cooler temps makes more females
male ratio.

1.higher phosphorous in veg makes more males

2.far end spectrum light in veg (hps) makes more males

3.too much stress makes either males or hermies