Growing lights

[Cadalot]

Bum I wish I had not continued researching grow lights before I purchased the LED Pad watching YouTube videos looks like my LED pad is doomed to failure before it gets here. I will obviously give it a go but now I'm also looking at CFL spiral soft white and spiral and the possibility of making something up like this guy in this video has https://www.youtube.com/watch?v=qdiVmoBQLG0

Just need to find a cheap source in the UK for the bulbs and fittings. Been punting around the internet this morning, looking at the local shops and DIY store web sites. Cheapest bulbs I have found in the so far BELL 20 Watt Spirals in 2700K and Daylight 5000-6500K at £3.38 & 3.86 each the dearer comes down to £3.40 if you buy 5. I have found one multipack of 4 x 20 Watt 2700K for a £10 but could not find an equivalent 5000K-6500K version.

I think a punt around ebay may be in order next, to see if I can source cheaper.

[Bigmallly]

I think you need to put it into perspective Al, If you want to grow "something" all year round then by all means go for an expensive setup. If it's just a case of getting a head start I think you will find the pad will be fine. I'm really pleased with my results so far & I got the spectrum all wrong.

[Cadalot]

I hope you are right, but that's not what I'm seeing on the YouTube video's. I think the way forward is to test the pad and see how it performs on it's own.

Then if the results are not very good perhaps look at adding one spiral bulb from each end of the spectrum on a suspension rig either side of the pad, and see how that works.

If not good results then the next phase will be to add another bulb either side of the pad so four bulbs in all two soft white and two daylight, evaluate and if still not quite there go for the 8 bulbs four soft light and four daylight, like the guys video and perhaps build the pad into the rear wall of the box.

[Bigmallly]

Unless you have something for comparison, you won't know if the results are in line with your expectations or not.

[Cadalot]

The comparison will be the same seed in the small Ikea greenhouse behind the kitchen patio window that I usually use to start them off.

[Shooter]

American sites tend towards 18 hours on 6 hours off bought an led grow light and tried that along side cfl they both work but I get better leaf growth and a more compact plant from the grow light

[JusPotterinTim]

For day-neutral plants you want to use as many hours as possible to give the plants their required 'dose' of light in a day for good growth, but I believe most plants need at least around 6 hours rest with the lights off so they can grow and refresh themselves, for want of a better term. For photoperiod sensitive plants you're more restricted as you can't just let them have loads of light always as this might affect the flowering adversely.

To go about it scientifically, as I do being an engineer, you need to know the lux level of the the lights somewhere just below where the top of their canopy is, and you can convert this into a measure of how many mols of energy the plants receive per day. The other part to the equation is how much light the plant in question needs for good growth.

So for my chillies, as an example, they require 21 or more mols/day of light energy for decent growth.

My 54 watt T5 HO grow lights give 20,000 lux (strength of light) towards the top of the canopy, say 10cm down from the very top leaves. I use this as the distance to work out the average light the plant is getting. Using the equations, that 20,000 lux and 16 hours a day which I run them for, and taking away about 1/4 because the grow lights are fluorescent and not the sun (the sun gives more bang per buck so to speak), means they're getting about 16 mols/day of light, compared to the optimum of 21+. I could run the lights for 18 hours a day to get a bit more energy to the plants, closer to the optimum, but for me they're growing well enough and I don't want to pay for more electricity.

What this ignores is that a stronger light penetrates the canopy better, so more of the plant's leaves receive the light they can process so more leaves are generating fuel for the plant, but it's an approximation. There's also a light saturation point for very strong lights, which means the plant can't use all the light fast enough when it's very bright, but in the case of chillies and fluorescent lights this isn't a concern. The light saturation point is about 50,000 lux for chillies (and some other light loving plants). A metal halide or HPS light could exceed the light saturation point, so you're not gaining all the benefit from the brighter light, but the lower leaves will see less shade. Sunlight gives about 110,000 Lux on a clear summer's day, for comparison.

So I guess the answer to how many hours you should run your lights for depends on how bright they are, in a nutshell. If a plant has received it's daily 'quota' of light in a short time, with a bright light, there's little to be gained from running the lights longer, as the plant needs a dark period to refresh itself, and use up the sugars and nourishment it created from the light, before it can utilise some more light. However, if your lights are relatively dim, then the more hours the better, but give them a break of 6 hours+ at night, and you might have to use less hours for photopoeriod sensitive plants depending on what you want them to do.

Some seedlings grow best with 24 hours of light when they're young, and mature plants need a rest at night in my understanding of it, but that's another issue.

[JusPotterinTim]

Just to add I use an app called Light Meter on my Android phone to measure light levels, it seems pretty accurate surprisingly.

[Sappidis]

Just to add I use an app called Light Meter on my Android phone to measure light levels, it seems pretty accurate surprisingly.

That actually seems like a good idea, I never even thought of doing that. Just got a single tube T5 so I'm not expecting the world but it would be interesting to see what it puts out

[JusPotterinTim]

That actually seems like a good idea, I never even thought of doing that. Just got a single tube T5 so I'm not expecting the world but it would be interesting to see what it puts out

Yes it's quite interesting I find seeing what light level the plants are getting. It helped me to figure out that with T5s you really want the light very close to the plants to get the most light to them, as it drops off quickly as you drop down a small amount. I try to get the tops around 2cm below the bulbs, this won't burn the mature plants, and allows a bit of room for the leaves to grow up without touching the bulbs, and the inevitable scorching when that happens. You really want 20,000 Lux to the top part of the plant, 30,000+ is ideal but probably a bit more than a T5 bulb will deliver. Below 20,000 I think you might struggle with lanky growing plants.

Obviously the more light they get the faster they will grow, which means they might grow too fast too soon before they can go outside.

I started with a single T5 bulb, and have ended up with three now, running for 16 hours a day, the three bulbs pretty much cover the whole of my mature plants with light.

Here's my setup:

[Sappidis]

Yes it's quite interesting I find seeing what light level the plants are getting. It helped me to figure out that with T5s you really want the light very close to the plants to get the most light to them, as it drops off quickly as you drop down a small amount. I try to get the tops around 2cm below the bulbs, this won't burn the mature plants, and allows a bit of room for the leaves to grow up without touching the bulbs, and the inevitable scorching when that happens. You really want 20,000 Lux to the top part of the plant, 30,000+ is ideal but probably a bit more than a T5 bulb will deliver. Below 20,000 I think you might struggle with lanky growing plants.

Obviously the more light they get the faster they will grow, which means they might grow too fast too soon before they can go outside.

I started with a single T5 bulb, and have ended up with three now, running for 16 hours a day, the three bulbs pretty much cover the whole of my mature plants with light.

Here's my setup:

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That looks great, are those the pots that are meant to be good to introduce air?

I'll have to measure the lumens I'm getting, I've backed them off because I've burnt the spinach but I'm going to be replacing it soon as they haven't done very well so should be able to move it closer.

[JusPotterinTim]

That looks great, are those the pots that are meant to be good to introduce air?

I'll have to measure the lumens I'm getting, I've backed them off because I've burnt the spinach but I'm going to be replacing it soon as they haven't done very well so should be able to move it closer.

Thanks Sappidis! Yes it brightens up the living room a lot in winter.

Yes they're actually called air pots. The idea behind the air is that it does a thing called air pruning of the roots. Basically I think the principle is that the roots that reach the side of the pot get funneled into the cones, which kind of catch the tips and force them towards the hole, and when they reach the end of the cone they hit the air, which stops them growing. This stops them from circling around the side of the pot like they would in a pot with flat solid walls. The holes don't seem to help much if the plants are overwatered, they still suffer - if potted up too soon into the airpots and watered heavily, it still takes a long time to dry out, and they can drop leaves etc.

So the purpose of the cones is mainly to stop circling roots, I think some nursery tree growers use them so their stock can not have circling roots that would restrict the growth once they're planted out. I've taken a year old chilli out of air air pot before, and the root system was very fine and fibrous, and filled the pot, with no circling roots, so the pots seemed to do their job. I think they're quite popular with the (ahem) herbal medicine growers too.

I think of the air pots as allowing a bigger/more productive plant plant in a smaller pot, as the roots are more efficient, so for my larger 6 litre pots I might need a 10 litre traditional pot to achieve the same size plants, if I let them grow unchecked. I do prune them though so they're not as big as they could be in those pots currently, but I do think they have more potential growth in them with those pots when they're outside in full sun, compared to normal pots.

I hope your plants come along well under the T5 bulb too!

[Deano's "Diggin It"]

Tell ya what! Although expensive!

Loving this "Concept"

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[Baldy]

Tell ya what! Although expensive!

Loving this "Concept"

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Looks good - won't even begin to try persuading Mrs Balders

[Baldy]

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