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Propagating Dahlias - Fall 2008

Posted by sturgeonguy 5a ON (My Page) on
Thu, Oct 9, 08 at 13:34

So, here's my second post in my Fall experiments theme. In this thred I'm going to post pictures of my frame construction effort.

Dahlia Frames 1

As you can see, these are simple 2x4 spruce frames sized precisely to hold 2 large garden trays from Lee Valley. Each tray holds 24 4" pots perfectly, so 72 pots in a frame. The frame is 36" tall on the outside, allowing for ~30" of growth height.

Each frame will be enclosed on all sides, including the top, with light reflecting material. My first experiment will be using tile board, 1/4" water-proof board used in shower enclosures. A single 2 bulb T5 fixture is going to be mounted in each unit. As soon as we have this one enclosed (later today) I will be doing some light meter tests to see, for example, how much difference it makes to move the light up and down or have a top piece of tile board.

I am also going to try light tests with nothing on the front. If the light is sufficient, I could then have these units in my sunroom housing existing Dahlias over the winter. I will also be testing using standard T12 shop lights.

Each unit will have locating posts (small pins) in the top, and corresponding holes in the bottom, so they can be stacked on top of each other. In my dinning room my plan is to have 2 stacks of 3 units.

I plan on sealing each unit in such a way that any bugs in one can't travel to another (easily.) Also want to keep in humidity, but I'll have to see whether I'm holding too much.

The front side will be completely removable so I can get at the plants.

The entire unit can be disassembled easily (wing nuts) so it can be dismantled and stored during the summer. I could put it on wheels, but so far I haven't decided if that's a benefit for me or not.

Cost-wise, each unit is running ~C$300 including the T5 lights and trays. The T5 lights are the most expensive component (~C$120) and the trays next (~C$80).

Comments and/or suggestions welcome.

Cheers,
Russ


Follow-Up Postings:

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RE: Propagating Dahlias - Fall 2008

Oops, I said they hold 2 trays, but they hold 3.

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

looks great to me.KEEP ON KEEPING ON. STEVE IN BALTIMORE COUNTY


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RE: Propagating Dahlias - Fall 2008

Really great Russ. I had the advantage to have a cage I had build years ago for my wifes Iguana. When he died I had to decide wheather to take it down or use it for something else. I added some shop lights under the two shelfs Gkar used. We had all these spot lights for Gkar. Everything worked out last year. This year will be better. I also have a 500 galon fish tank. I have a shop light over that , plus spot lights on the edge. Your idea is wonderful and will work well.


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RE: Propagating Dahlias - Fall 2008

Russ, I love that you nonchalantly explain that you will winter two stacks of three units of dahlias in your dining room. I think it's great. and your house is great for it with all the windows, I couldn't begin to do that in my house, not enough space...but even if I could, I am pretty sure my husband would start tearing down engines and carburetors in the living room just to make a point...

Nice work, and congratulations on the Mayor's excitement about your blooms!


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RE: Propagating Dahlias - Fall 2008

Sorry if that came across as a brag...I was just trying to explain the setup...;-]

So we did light tests today. Results are discouraging, but they are what they are.

The absolutely ideal goal would be 4000 foot candles. I could offer some conversions (to lux or lumens) if people want, but for now we'll stick with f.c. 4000-6000 f.c. is direct sunlight.

Interestingly enough, I can get this amount of sunlight inside at various times, but only for short periods of time and only in certain spots. Generally speaking, the room is ~150 f.c. on a very sunny day. Clearly not enough.

So I tried a single 4' T5 dual bulb fixture. To get 4000 f.c., I need to have the lights ~2" away from the top of the tray. I get ~1500 f.c. at 4". The spread on the light is ~2" from the bulb before you start to lose f.c.

I am getting 270 f.c. in the middle of the tray when the light is 14.5" above the trays. I get 200 f.c. at the outer edge of the trays.

For comparison, I put a 4' dual bulb T12 fixture in. At most, I could only get ~1000 f.c. At 14.5" I got 140 f.c. in the center and 120 f.c. at the edge. Guess the larger bulbs spread better.

All this testing was done with white tile board on the sides. I had one side off, and nothing on top. Adding a top piece made no difference, and my readings where there was a board on the side versus the side that didn't have one were the same. IOWs, the white tile board adds nothing.

I then added tin foil on top of the tile board (just the area below the lights.) Tin foil, somewhat wrinkled, added a lot. I got 400 f.c. in the center, and 400 f.c. at the edge. So clearly having sides, with some sort of reflective material, makes a big difference.

This was essentially the same as doubling the light fixtures. With 2 x 4' double bulb T5's I got 350 f.c.

So, now its back to the drawing board a little...

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

Russ,

In the spirit of experimentation, I'm offering to be your humpback assistant. I don't know what the ceiling of your sunroom looks like but unless you have natural sunlight coming through the ceiling I think it's pretty hard to replicate the light you'd get in a green house . I kind of expected you would get those light readings. If you want to stick with use of T5's, it's still possible to get the 4000 fc you are looking for, with a few adjustments, however. You probably already know this but the type of reflector does make quite a bit of difference. The thing with tin foil is, the more FLAT you can get it, the more effectively it will serves its purpose. Another option is to get reflective mylar at a hydroponics store. There's also debate on whether a white reflector or aluminum reflector works better. Also, any reflector is better than no reflector.

Have you tried out one of those T5 fixtures with the german aluminum reflectors? You can get 4000fc with one of these fixtures. A 4 feet 8 tube New Wave T5 fixture with the aluminum reflector will give you 3600fc at 11 inches under the tubes. This was a light reading done with a reliable light meter by a member at an orchid forum elsewhere.

If you want to cover a bigger area with less fixtures you'd have to go with a high pressure sodium fixture or metal halide. These will give off a lot more heat compared to fluorescent tubes though. However, they can be placed much higher above the plants.

I hope you're successful with this experiment and I'm cheering for you!


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RE: Propagating Dahlias - Fall 2008

All right linht thanks for jumping in. I will be lining my greenhouse (GKar's) cage with aluminum foil.


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RE: Propagating Dahlias - Fall 2008

Linht,

Thanks!! According to an online hydroponics site, the growing area for a 4 4-tube New Wave T5 HO fixture is 4 x 2.5. Thats almost exactly my growing space in each cabinet. The growing area for the 8-tube unit is 4 x 4, more than I need. I would like to assume that I should be able to achieve 3600fc at 11" with the 4-tube unit in my space.

I compared the price of single unit fixtures ($49) with reflectors ($30) to multiple tube units (4-tube=$395), and funny enough, theres a considerable difference. I can save ~$80 per cabinet and all I have to do is cut a couple of 2"x4" to attach the 4 fixtures and hangers to.

I am going to get 4 German aluminum reflectors as an experiment. I will see if theres a difference with them, and if so, how much. I am now planning on making a canopy with the fixtures attached. The canopy will be a piece of board covered with 2mm reflective Mylar film. My thinking is that this should be almost as effective as aluminum reflectors, and considerably cheaper. Ill use 2mm Mylar reflective film (~$1.06/foot) on all sides as well. That should make the entire cabinet reflective under the lights.

As I already have 6 double T5 HO fixtures, this will do for 3 cabinets. For the other 3 cabinets Ill get single T5 HO fixtures so I can more evenly space them across the space.

The additional lights certainly add to the cost per cabinet, but not having to use board on all sides has reduced the cost at the same time. With 4 T5 single-tube fixtures, without reflectors, the cost before tax is now ~$335/cabinet. With reflectors the cost is ~$455. Using my current price for electricity ($0.114/kwh) each cabinet will cost ~$0.35/day to run.

So now I have to get the materials to make the next set of light tests.

Viking, FWIW, the Mylar is more expensive than tin foil but it does have distinct advantages. Firstly, it doesnt ripple the way tin foil does, and is less likely to tear. This should mean it will yield a more even surface to reflect light, and be easier to work with. Also, you can get it in 4 wide rolls. It claims it has 98% reflectivity, which is higher than even panda plastic.

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

Russ,

I've never heard of panda plastic but it sounds scary to me.

Unfortunately the 4 tube 4ft fixture will not give you anywhere near the 3600 fc at 11 inches under the tubes because it's only 4 tubes, thus, less light. I have a light meter that's given nicely accurate measurements. You know all those James Bond gadgets you have?? Well this is one of mine, hehe. I forked out a lot of dough for this meter because, yes, I am that crazy when it comes to my orchids.

So.....I did some measurements for you. You said you want to use the 4 ft 4 tube fixtures, right? I have a New Wave 4ft 4 tube fixture and this is the reading I got. These have the angled german aluminum reflectors built in. My grow area under the lights is NOT encased so I am not using any reflective material on the sides. For brand spankin' new tubes (not one that've been in use for 6 months), 3600 fc is what I got about 4 inches under the tubes on that fixture. Of course, if it didn't have the reflector, it would be considerably less. The only way to get 3600 fc 11 inches under the tubes is to use a 4 ft 8 tube fixture. Hope this helps!


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RE: Propagating Dahlias - Fall 2008

Linht,

Thanks very much. I've no problems keeping the tops of the plants within 4" of the bulbs, or closer even. We'll just have to see how the already blooming Dahlias do. Right now I'm actually more worried about what will happen when I take the plants out of the ground and move them inside, cutting roots and possibly tubers in the process. Hopefully they won't go into too much shock.

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

Hey Folks, if you want to laugh your a** off watch a movie called 'Saving Grace'. It is British and hilarious. It has an indoor growing theme.

Here is a link that might be useful: Saving Grace movie trailer.


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RE: Propagating Dahlias - Fall 2008

Well, more updates.

I have the 6 cabinets built and positioned in their place, here's a picture:

New Cabinets

Each cabinet also has a door (actually, just another side panel that slides into a couple of rails.)

I'm pretty much done with the light experiments.

4 x 4' T5's with reflectors inside the mylar lined cabinet:
700fc @ 14"
1000fc @ 10"
1500fc @ 4"

4 x 4' T5's with mylar laid flat above the lights inside the mylar lined cabinet:
500fc @ 14"

4 x 4' T5's with mylar laid in a "W" pattern to simulate reflectors inside the mylar lined cabinet:
800fc @ 14"

So I'm going with the "W" patterned mylar, given the reflectors are $30 each ($120/cabinet.)

Here's the light rig with reflectors.

Lighting Experiment

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

Boy Russ you have done a really nice job. I see you are a fellow woodworker. I am doing paneles this week for my flower boxes.

John


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RE: Propagating Dahlias - Fall 2008

You know,, people don't understand how dedicated we are. I get in trouble by telling [people I can't go away for a weekend because I am watching the dahlias! They think I am nuts. Well they are gone now. Good work. Wish I had your room.


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RE: Propagating Dahlias - Fall 2008

Here's a composite picture of my light fixtures.

New Lights

Top Left: This is the top of the fixture. If you look closely, you'll see the slats on edge that run left to right to force the mylar to enclose the light fixture.

Bottom Left: This is a fixture using double-bulb fixtures. I had 3 8' fixture that were made up of 2 of these double-bulb units. They aren't going to give as even light as the single fixture units, but I wasn't going to buy a bunch more just for that.

Right: Here you can see how the mylar makes the "W" shape around the single fixtures. If I was going to make more, I'd make them like this. As I mentioned, I get slight better foot candle output from these than from the ones with the "german" reflectors that were $30 each.

Tomorrow, I hope, everything is finally done.

Cheers,
Russ


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RE: Propagating Dahlias - Fall 2008

Really nice work Russ. I started assembly on my new flower box today. I am working very slowly. I am hoping to make about 6 new boxes for next year.


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RE: Propagating Dahlias - Fall 2008

So I found a neat new toy from a company called UPM, its the EM100 Energy Meter. You plug it into a wall outlet and then plug in anything you want to meter into it.

In my case I have all of my lights for my Dahlias plugged into it to see how much power they're consuming.

24 x 54 watt T5 bulbs for 14 hours = 15.5kwhr = $1.77/day (in our area.)

If you ever wondered just how much something was costing you in electricity charges...its a great way to find out.

Cheers,
Russ


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