What's new
By:
GrowWeedEasy.com
You're browsing as a guest. Sign up to join the conversation, share your grows, and get help from thousands of fellow growers — it's free and takes less than a minute.

MH distance from seedlings?

W

wordologist448

New member
Just a quick question - I switched from 2x300w LEDs to 400w MH/HPS midway through my last grow, so I never had the baby seedlings under the MH light before, and I'm wondering if the "14 inches between the lights and the plants" general rule applies right from the beginning. Here are some pics of my plants; the two I shot from the side are the ones I'm wondering about - do they look okay, or are they bending that much from overlighting? They're both the same strain (Blue Dream), and the other two (Blue Mystic) just aren't growing as fast, I guess - the bottom of the light box is ~15-16" above the pot rims now; should I raise them some more? I've had past seedlings get stretched from having them too far from the LEDs, so I'm trying to find the right balance :p - thanks!
20180718_152545.jpg
20180718_152536.jpg
20180718_152514.jpg
 
Get some support on those taller ones. And as long as it isn't too hot to hold you hand over for about 30 seconds it should be ok
 
Really? When they're that little? Gotcha; I haven't bothered before! And yeah, not too hot for hands; there are 2 6-inch fans blowing back and forth across them, so even though the thermometer says 85, I don't think it's even that hot!
 
I've been doing the same thing and asking the same question. Was pushing the mid-80s° without a fan but now we have settled in to a nice mid-70s° with a fan. My 400 MH is about 12" from my 10 day old plants and they are doing fine. I too was worried about how close to keep them to the light but even at that distance and without the fan there was no discomfort leaving my hand right on top of a plant for minutes let alone seconds.

As for the leggy babies I was reading more on that and for what it's worth, I just filled my pots with more soil to support the growth. Some have suggested that you could go right up under the leaves and that the buried stems would start springing roots. In your case you might need to add a few inches tall pot ring in order to add more soil. I think this would work better than standing sticks next to them. Total newbie though so don't take my word for anything. :rolleyes:

Crow
 
Last edited:
I've never used metal halide on seedlings, so I'm not any help.
I always use 23watt cfls for the first week or 10days, then I use my 315cmh about 22inches away.
Those long stretchy ones need more light though. GoodLuck with them,
I've grown BlueMystic autos from Nirvana, several times, and they grow really well after their roots get established. And smoke even better.
 
Yeah cfls are beasts for seedling growth... I had some under my mh but they don't need that intense of light. They grow better under the cfls till they get a bit bigger. Once I get em out of the solo cup they go under the hids 😉.
 
I have found blue dream stretch a little more than others. However there are a few factors that you must keep in mind.

Stretching is a morphology reaction to many different environmental factors. For example light intensity, wavelength, temperature difference, nutrients etc. All play a role on the elongation of plants. I touch a little on this with stretching during flowering.

What you are seeing looks like an effect caused by phototropism and elongation. Intentional growing in one direction to find more light or more of a specific wavelength of light, such as blue. They are trying to move towards the center where light intensity is highest.

You may want to look at my article on environment conditions and using light efficiently, where i touch on factors such as light intensity, temperature, airflow etc and how it impacts plant health and performance.
 
I've had really good results with cfls and burying up to just below the leaves, as well.
I managed to fry young plants with my 400 MH this spring, so am leery of using it on seedlings now, though sounds like you can totally do it.
 
You must log in or register to reply here.
Back
Top