Growlights: Building the Perfect Grow-Box

As some of you will know I have a Metal Halide grow lamp. I use it for over wintering taller / denser-canopy plants, and then in the spring to bring-on young plants / seedlings. MH lamp is a good 24" away from the plants

I know that many of you have lighting rigs (tubes or CFLs) which you use primarily for seeds and cuttings (lights will be within a couple of inches of the plants)

There are other threads that debate the merits of the various types of lamps ... my aim in this thread was to discuss the "ideal design" for a grow-box using Tubes or CFLs within inches of young seedlings, as I have a number of questions (being a detailed, OCD, sort of a person ... )

For anyone looking for general discussion on grow-lamps in general these threads may help:

Grow lights, heaters etc, on a budget
Grow Light germination ?
Other undercover growing?
Grow Lights
PeterS's Light Box (members gallery)

So: your thoughts on any of the following please, specifically related to a grow-box lit by tubes for growing seedlings / cuttings only.

Various sizes of light rig available:

29cm x 35cm - 4 x 1'?? tubes, square
29cm x 60cm - 4 x 2' 24W tubes
54cm x 60cm - 8 x 2' 24W tubes
38cm x 119cm - 4 x 4' 54W tubes
64cm x 119cm - 8 x 4' 54W tubes

Obviously size is relative to the space you want to grow.

Is it useful to have several, separate, light rigs so that they can be turned on individually according to number of plants at any given time?

Is the sideways light-spill from a narrower light rig enough for peripheral plants? e.g. use a 4-tube light rig (30cm) in a growing space, say, 45cm wide?

With a wider (8-tube) light rig would you consider turning off half the lights? (some are switched to allow just the middle 4-tubes to be run). Obviously this works if you only have 50% plants in the grow-box.

But are there circumstances where you would run alternate lights only (for lower light levels)

Single tier or double tier?

It strikes me that with double-tier it would be easier to construct a space that has one low roof and one high roof, so that plants can be moved to the higher roof space when they become too tall

Lamp timer:

How many hours per day do/would you use?

Would you consider doing lighting "batches"? and if so how do you physically do that? Move the lights, or the plants? Perhaps the light rig could be on a frame with castors so that it can easily to rolled to front/back half of the growing cabinet. The other half can have the overspill lighting presumably? (There has been separate discussion about the benefits of having a dark-period for part of the 24 hour period)

Any special requirements for the timer?

Adjusting lamp height:

Have the lamp on chains / easi-rolls to allow it to be moved up & down, or move the plants nearer the lights? My experience is that plants are variable height, so I have to raise some up anyway. Might, therefore, be easier to have the lights fixed and give thought to making it easy to adjust the height of the plant pots / trays. e.g. have all the plants in small-ish gravel trays of some sort, and use "chocks" tor raise the trays.

Insulation / heating / ventilation

Assuming this is indoors, rather than in a greenhouse, what are the issues here? Will tubes create too much heat such that the box needs ventilation?

Soil warming:

Is it sufficient to use a reptile warming mat with a thermostat? Presumably a thermostat actually in the soil [of a pot] is best?

Again multiple mats so that only areas in use are heated? What happens when plants need different heights to the lamps? Perhaps another reason for having multiple, smaller, lighting rigs rather than one larger one?

Anything else you maybe wish you had done, or would advise doing, differently?

I did have a look at some Propagation Tent kits - they look a bit flimsy to me, and I think it would be cheaper just to nail some bits of wood together:


40cm x 120cm £45 http://www.3ch.co.uk/accessories/clone-tents/clone-cube-tent-a/prod_1267.html



80cm x 120cm - 2 tiers (100cm high) £150 http://www.3ch.co.uk/accessories/clone-tents/clone-cube-tent-f/prod_1278.html

 

My project is coming along nicely. I now have the heat mat, which I is 23x11 inch vivarium heater one, and the first of my LED panels (I have purposely arranged my design to accommodate more if they prove to be any good).

I have an old cupboard and have installed power (a four way socket), and sorted out shelves that can be easily adjusted and repositioned.

But then it occurred to me that there is one thing I hadn't thought about. Fungi. Ventilation is obviously essential, but I don't think it will be enough just to allow air to move within a confined space. I think it may be necessary to routinely use fungicide when cleaning the cabinet and watering the seedlings. Or, I have a small UV lamp that I might add, which might help to control fungal spores.

 

I like the idea of reusing an old cupboard

Don't think I've and any trouble with fungi using my Grow Lamp (but it wasn't confined to a box, although I do use it in an enclosed "blow-away" in the conservatory in the spring); I think the warmth inside will be sufficient to prevent fungi - but maybe that means that it will be too dry? and I will need more humidity for the box to do well - and that could lead to fungi problems?

Bugs have been my problem. Warm, Light, Perfect conditions for critters :(

But easy enough to put a computer-case fan into the box. Some of those grow-tents that the hydroponics boys sell have all the ventilation taken care. Here's the back of the 2-tier one above - with ducting for extractor fans

 

Re: batches - I made my box so 2 large gravel trays (Garland sold at Dobbies, but I got mine cheap from a bargain store) would fit (under 2 matching size T5 lights), so I could have numerous trays full of square pots and easily slide them in/out for quick swop overs.

 

Where do you put the plants that are in the dark though? If that space is "available" then I think I prefer just rolling the light rig over the other-batch - nothing to drop whilst trying to manhandle the tray etc.

But that doesn't answer the "period of darkness" which physically moving the tray would solve.

 

I don't have enough room for a box big enough to have 3 times (or even twice) as much area as my two T5 lights so the lights could be moved rather than the plants/seedlings, especially as I intend to move it indoors from the greenhouse over winter. When only using a double shift the trays go on top of the grow box, and when there's more light and I used 3 shifts I also used somewhere else.

An adaptation before next year will be a removable panel between the areas illuminated by each light so they can operate independently. A further adaptation will be wallpapering my daughter's bedroom with Mylar when she goes to Uni. I'm reluctant to use our roofspace for a big grow box because of stories like this: http://www.dailymail.co.uk/news/art...ry-discover-home-guinea-pigs-Simon-Kenny.html

A few more thoughts... I lined the base of the grow box with white polythene to reflect light from unused areas and prevent water leakage. I've searched without success for white gravel trays or even white cat litter trays. My T5 tube lights don't cause any heat build up.

 

There was a case in the news a while ago where a bloke had all his tomato plants confiscated on suspicion that they were cannabis plants, after a neighbour reported an unusual smell coming from his greenhouse

The man even said to the coppers, can you not see that they are tomato plants?

 

Brilliant idea! Although I think she ought to re-paper it herself before she leaves

"When only using a double shift the trays go on top of the grow box"

Of course <SlapsForehead>. Good idea.

"removable panel between the areas illuminated by each light so they can operate independently
My T5 tube lights don't cause any heat build up."



"I lined the base of the grow box with white polythene to reflect light from unused areas and prevent water leakage"

I was planning on using Polystyrene - it is surprisingly (well, to me at least!) highly reflective (not falling far short of Mylar), and will insulate too of course.

But I ought to give some thought to the base being waterproof, for use indoors.

 

Hiya

Have you got photos of your grow box?

Amy

 

The Halide will burn out timers. You'll need an adapter to run it called a "contact relay".

Light on/off period depends on the type of plant. If a poppy is under 20 on, 4 off, it will flower. Where as 8 on, 16 off will keep it dormant.

Clueless mentioned airflow which is needed but any plants spacial needs must be tailed. So whatever the plants natural environment for living is, is the environment you need to mimic. Know your plant is the best guide to success.

Also, even NASSA are cool with LED's. Plant Photonics make good led lights. Cheap to run and without killer heat issues.

 

I haven't built mine, as yet (see update below). In previous winters I've just "dangled" my lamp above the plants (and put some sort of make-shift reflector around the perimeter - e.g. a white cardboard box, or one with kitchen foil attached (although I have since learnt that kitchen foil is not a good reflector of light). This year I need something for bringing on seedlings, and thus want to try a grow box.

Here's how my plants looked under a hanging light. These are some Cannas under Metal Halide, 8 weeks after germination:


Here is PeterS's lightbox from circa 2007:


Thread: http://gardenerscorner.co.uk/forum/threads/light-box.27919/

 

Thanks. I have a contactor for the timer on my MH lamps. For the grow box [this is for germination and brining on young plants, rather than growing on / over Wintering taller plants which need canopy penetration light] I'm planning to use Fluorescents and my question was related to that. My understanding is that you can just plug them into a timer without burning it out?

 

Update:

I've bought a 2' square lighting rig ["T5 light 8 Tube Short. 54 cm x 60cm"] with the skinny fluorescent tubes (from Amy's company 3CH).



Waiting on arrival of a light meter to compare output with MH (purely for interest) and to check how the light power falls off with distance, and the strength of the light that is projected sideways.

I'm then planning on having the lighting rig able to move front-to-back to allow for two batches, the width of the bit in the middle will be calculated once I find out how "wide" the useful light throw is.

Also looking into whether it is easy to change the lighting rig to switch half the lights off - so that when I only have a few plants I can halve the light - and the running cost.

I took the opportunity to also order some Canna Terra Vega liquid fertilizer (which I have found excellent for early feeding in the past), some Clonex (not tried that before, only ever used powered rooting hormone), a box of Scalpels (find them much better for getting clean cuts on cuttings than a knife) and some "Easy Rolls Light Hangers" - I have those already on my Metal Halide lamps, and I figured they would be easiest for the grow box, although it may turn out that fixing the lighting rig to the "roof" and moving the plants up/down to get perfect distance may be the solution - as they will, obviously, grow at different rates.

I also bought a new Metal Halide bulb so I can compare output from old & new. Old one has done 2 Winter seasons

 

Excellent thread Kristen.

Grow lights are fantastic fun because you can be actively gardening and growing things inside over the winter. I have had great pleasure from mine.

If I may add - there seem to be different uses for grow lights, which give rise to three different set ups.

1) Active growing of large plants. This is what Kristen has been describing. This needs high power Metal Halide lamps, which produce a lot of heat and so need to be some distance from the tops of the plants so as to not scorch them. But as they are high power they will deliver a lot of light to the base of big plants, which is just what you want for active growing.

2) Seedlings and cuttings. These will be much smaller consequently you can use fluorescent tubes, which will be lower power and create less heat. But you can get the same high light levels by placing the tubes within 2 or 3 inches of the tops of the plants. Overall this will be cheaper to run but is only suitable for small items.

3) Overwintering plants. In this you simply suspend a fluorecent tube over some quite large plants inside the house . The light level will be low, and if this is combined with a moderately low temperature, ie 10C to 15 C, say in an unused bedroom or in a hall (in the picture below), it will allow tender plants to tick over in a semi dormant state over the winter. They will still grow - but very slowly.

 

Conversation on grow lights always wanders around the various types

You're right that I have MH and use it to overwinter plants with lots of foliage ... time is now for me to build a grow box for smaller things, seed I want to start early and for bringing on more seedlings in the spring

So in this thread I am keen to specifically discuss a Grow Box for seedlings / small plants / cuttings (so fluorescents rather than Metal Halide).

Are there things you would change / do differently if you were starting-over with your Grow Box?