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Oak Grove, Mn

In a few months, there will be the posts of the pumpkin growers talking about the lights to start their seedlings under. Many will say, nothing better than a T5. In addition to T5 and T8's, there are HPS, Metal Halide, Ceramic Metal Halide, plasma, LED, COB LED and now I am reading about the next generation...quantum dot technology. The weed growers will probably be paying for the research costs, eventually it will be affordable to all.

What do you think is the best choice for those that just need seed starting, those that might want to supplement a green house with extra light and those that are full grow winter.

1/12/2020 3:36:11 PM

Norfolk, UK

That, Bob, is a most excellent question. :)

I've been toying with supplemental lighting to aid quick vegetative establishment post transplant in my outdoor greenhouse.

Light is weak first part of the season and the position of my greenhouse is such that it comes into better (and more hours) of light as the season progresses vs the start.

LEDs are what i had looked at, but the challenge that i had seen was around trying to find lights (whichever kind) that might be water / splash proof to put up with the humidity, drips and occasional foliar spray in greenhouse vs indoor grow.

I've still not come down / decided on anything, but it's on the radar as something to think about. I wasn't sure if you needed the "bloom" type of lights to help trigger megablooms or pure vegetative might influence formation of blooms differently tho. No idea of influence or impact there.

Be interested to hear thoughts from folks who know rather more on the subject than me!

1/12/2020 4:47:34 PM

Grittyville, WA

Yeah my "indoor" LED light suffered corrosion when it spent time outdoors. I think that's a reason to go with an outdoor commercial floodlight/security light which can be found at the useful 6000 k spectrum. I don't like the LEDs that are full spectrum... hard on the eyes, but the security/floodlight type don't have that issue. But I am not trying to grow a high value crop... it doesn't matter that me what grows buds best. Pumpkins like T-5 or white LED just fine in my experience. The T-5s might grow more compact plants the pumpkins under white LED look very natural... they look normal.

1/12/2020 7:33:01 PM

Wixom MI.

Nice timing bob !!! Because of my new kitten climbing and eating all my house plants witch are poisonous to cats, i was forced to buy a new light to keep my plants alive in my dark bacement.i know nothing about led lights but when i went to my hydroponic store all they had their were the new quantum board led lights. So i had no choice but to buy their smallest one. It is a DDXV1 high efficiency quantum board uses 240 watts and a 4,000k spectrum.I dont understand how to compair a 300 watt halide light to this quantum LED lamp but it seems to be much brighter than my 300 watt halide lamp. I just put it up last week so it's going to be awhile before i know how good it is.but i will put a picture in my diary to show you the difference.

1/13/2020 1:20:36 PM

Norfolk, UK

@Chris - I was expecting a couple of pot plants in the basement; not a whole garden centre!! Light looks good fella. Hopefully the kitten will grow out of it in a bit :)

1/13/2020 2:53:49 PM

Oak Grove, Mn

That light looks really nice Wixom. I wish these were available when I purchased all my purple lights. I would love to test it with my PAR meter but from your picture it definitely looks brighter than your metal halide. How much heat does it produce. I am sure SaladDoug is curious if it is waterproof. I think you did good.

1/13/2020 4:51:45 PM

Wixom MI.

Their is Very little heat comming from the light. You can put your hand on it and it feels like a medium hot cup of coffee. The small balest is like touching a hot cup of coffee. They don't give instructions on how to hang it so to be safe i used 4" long screws and let it hang 3" off the floor joist.im not comfortable with scewing it directly to the wood surface it feels like about 120° ?
I will post some pages in my diary on light info and waranty.

1/13/2020 5:34:29 PM

Oak Grove, Mn

i somewhat looked at the specs wixom...after hurting my neck trying to read it at 90 degrees. It is saying 240V. Do you have it connected to 120 or 240. It also is saying about 3 umol/J .. which works out to about 900 umols/300 watts. I am wondering what distance they are measuring at. I am thinking my ceramic metal halide is over that number but those number are really good for a low heat, white light, grow light. Maybe the tomatoe growers will convince these T5 pumpkin growers that the ultimate is not what they think.

1/13/2020 6:24:47 PM

North Pole,Alaska

I was going to let this thread go for awhile to hear the opinions out there, but Bnot is nudging me to join in, so here goes.
Your initial post addresses 3 different scenarios, and of course, 3 different answers are required.
Seed starting is probably the easiest for a number of reasons, but also where the most mistakes and most mis-spent money is.
Supplementing a greenhouse is specific to the area, the crop, and EXACTLY what you are trying to accomplish.
Indoor winter growing is the most complicated because of the poor design of commercial lighting for the application tomato growers are trying to use it for, especially in small areas. Your inverse square law, Bnot. As well as the logistics of environmental controls in a small room with larger, quicker shifts in heat ( ambient, root, leaf surface), humidity, EC, light,root moisture, etc.
Outside you have natural buffers, with slower transitions from one extreme to the other. Indoors you have to BECOME Mother Nature.

1/13/2020 9:04:20 PM

North Pole,Alaska

Lets start with seed lighting. Most of you are getting good results with your current lighting set ups.The main point most are missing, is that transplant shock is less about root shock and more about light and temperature shock, if proper care is taken. For most experienced growers, you are probably doing a great job in that respect.
Hardening off a plant is more about light stress. Basically, plant leaves develop in direct response to the environment. All other things being equal, higher light intensities will create thicker leaves with smaller leaf surface area, and a higher density of light sensitive pigments. Lower intensities, the opposite, as long as they aren't light deprived.The important point here is that the ratios and concentrations of pigments are directly related to the intensities and wavelengths of light available during development. If you grow indoors with a strong blue light, a little red, no green,no far red, and no UV, THAT is what the existing leaf is able to utilize for energy production once transplanted outside. Only new, developing leaf tissue will be able to utilize the full natural spectrum of sunlight.
So regardless of how healthy your plant looks prior to transplanting, it will have a reduction in growth once exposed to natural light UNLESS you duplicate the natural spectrum indoors. In general, it will have higher respiration demands, while being bombarded with wavelengths it can't initially process, or in the case of UV, protect itself against.

1/13/2020 9:45:49 PM

North Pole,Alaska

Don't waste your time and money on expensive lights for starts. Concentrate on good root growth. Pumpkins, squash, and corcubits in general will do better with less initial light than something like tomatoes, whose roots don't lag behind. I start mine with regular cool whites about 1" max above plants until about 6" tall, then switch to Metal Halides. Only 12 hours per day max. Much better initial root growth. Max 600u/mols. A good gauge for determining initial root/plant health is the cotyledons. I normally have healthy cots on vines 12-16 ft long because they weren't stressed young. NO transplant shock, even though they travel 5 miles in a van bare rooted to get to my greenhouse. They are usually 5-9 ft vines during transplant.

1/13/2020 9:46:10 PM

North Pole,Alaska

I'll comment on the next 2 scenarios after some feedback on the first one.

1/13/2020 9:47:05 PM

Oak Grove, Mn

I was right, I thought you would have some valuable input daveigiantguy. For spring seed starting I have used my T5's, led's, cob led and my ceramic metal halide. They all seemed to do the job. The T5's seemed to take a bit more effort to keep the light the proper distance from the plant. Another thing that affects root/foliage formation is DIF. This is the difference between day and night time temps. Depending on the light source, heat becomes an issue.

1/14/2020 6:16:33 AM

Norfolk, UK

@daveigiantguy - interesting read on potentially the leaves only developing / or using the spectrum that they have been used to at that point.

In my particular scenario (supplemental light on the shoulders of the day) on early stage tomato transplants planted into final stage positions in an outdoor greenhouse, i'm hoping it'll have exposure to both.

In the early part of the season, my greenhouse is part shaded through the am, with light hitting beds between 10 and 11am despite a 6 or 7am sunrise.

Later in the season, it's less of an issue. Stuff grows - I got a 6.11 lb out of it last season. Warmth above and below ground I can provide but early season light is not ideal. I transplant at an early stage - any where between pre-chitted seed sown in situ to first leaves through).

Interested to hear your thoughts on stage / scenario 2! :)

1/18/2020 5:44:35 PM