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Thread: Mist System

  1. #1
    Join Date
    Feb 2002
    Posts
    598

    Mist System

    Mist propagation

    I had heard for years about the use of mist on softwood, ripe new wood or evergreen cuttings to make them easier, and in some cases possible to propagate. As I began to read and visit folks who use mist for propagation purposes, I found that there were many different approaches, and always something objectionable would come up about the particular setup I was visiting or reading about. So, after all my investigation, I determined to solve as many objections as possible, and still keep the thing simple.

    Theory:
    The goal of a mist system is to keep the cutting from drying out and dying until it can generate itís own root system. The way it does this is to keep the leaves damp so they do not draw all the moisture from the stem though normal transpiration. Transpiration water loss is also reduced by keeping the cuttings out of any direct sun light, or keeping the humidity very high.
    Generally mist heads will generate a cloud of spray that will cover about 4í in diameter, and are placed around 4í above the cuttings. So, in my system there are only three mist heads (mist generators).


    The actual construction consists of a very simple box, built primarily with 2"X4" treated lumber. The box is 4í wide and 10í long. It stands 5í high, and there is a floor frame, that stands just 1í from the bottom. The 4 legs are 5í tall. Each side built first with a 10í 2X4 at the top, and one, 1í from the bottom. Then these are joined by 4í 2X4ís on the end. We use 3" treated screws to hold everything together. Once the 4 legs are joined by the side and end pieces, we used 2X4 angle braces in each corner to keep it stable. So far, everything is really simple.

    Next comes the mist controller, or timers that some folks use. There is no rule of thumb for misting timers. The timings all depend on a set of variables, and changing factors. Some of which are the normal relative humidity, wind, sunshine (or) rain, and the temperature. Iíve read about timers that will automatically come on for 10 seconds every 10 minutes. In my environment, that would be far too much water. However, in some of the dryer parts of the world, that would not be enough. That is why I selected the "Mist-A-Matic" controller. A fine mesh screen, that captures moisture, in much the same way as a leaf, turns the mist off when filled, and on when itís empty. With that single device, there is no need for 24 hour timers, nor integral timers. The amount of mist (duration and frequency) depends on the weight of the water on the screen, and your setting of a counter balance on the other end. The whole thing is pretty much weather proof, but we do like to keep things separate to some degree. Inside the garage I have a transformer that converts 120V house current to 24V, and a lead (standard low voltage lighting 2 wire from Home Depot) that runs out to the controller, then from the controller to a 24V ĺ" solenoid valve. Just ahead of the solenoid is a micro screen water filter that will hopefully catch anything that would stop up the little mist jets. By the way, the valves, and filters are also available at our local big box stores.

    But one of the many problems reported was the difficulty in keeping the mist from drifting away from the plants, even in the slightest breeze. To keep the mist from drifting, we draped a white fiberglass sun filter, or screen over the top, and down the sides to below the floor. The ends are sealed with clear plastic. The screen does not prevent all sunlight from entering, it is quite bright inside, and the white screen helps reflect some of the light. The actual "floor" is nothing but the sides of a steel wire frame that I happened to have laying around. No drainage problem there.

    Media
    Another problem with mist propagation is the collection of too much moisture in the rooting media. Regular potting soil would remain water logged and ultimately kill any roots that did develop. To compensate for this, many people use 100% perlite as the media. I prefer to mix a bit of vermiculite and sometimes half fine pine bark chips. Even course sand will do, but it is really heavy. The trick is to get the bulk of the water to drain out so the roots do not suffocate.

    Containers
    The containers that I stick the cuttings in are mostly 2"X2" cells, that are about 2.5" deep. By the time roots develop, the combination perlite/vermiculite will hold together long enough to transfer the entire contents over to a larger pot when itís ready to move. I chose this method because some plants resist transplantion in their early stages.

    Source

    The mist controller, mist heads, and attachments all came from Mortons. All of the other ĺ" plumbing supplies came from Home Depot or Lowes. You could build a much more elaborate system with insulation and bottom heat and lightsÖ. But this works for me and does exactly what I intended it to do.
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    Tom W
    Aching Back Farm

  2. #2
    Join Date
    Jan 2002
    Posts
    443

    so what is yor real question

    you spoke of so much , i dont know what you really what to know.
    i use coarse sand
    i have a 24 timer over a 10 minute timer

    i start out with the ten min timer every 5 mins
    after a few weeks i switch it to once every 10 mins.
    it aint rocket science but you have to watch the cuttings!!!
    if you dont get all of your cuttings done in a day or 2 you will need more beds and more tmers and solenoids valves.
    thats why the generic propagator has to get busy in a few short days and adjust his timers when things start to root so plants dont decay because or of too much moisture, et al fungus etc....

  3. #3
    Join Date
    Feb 2002
    Posts
    598
    Thanks Shepp,

    There really is no question in my post. I am just sending an example of appoach to the 'mist' function.
    But your point is well made about altering the mist frequency once the plants get established. With the Mist-A-Matic that is handled by spinning a counter ballance forward on the back side of the switch ballance.

    The conditions around the cuttings change often. This system keeps the moisture level pretty much the same, day and night, in high or low humidity environments.
    Tom W
    Aching Back Farm

  4. #4
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934
    Thanks, Shepp!

    I am hoping your schedule will permit you to show us your misting system soon, and you can tell us more about what you have learned from using it...

    Tom!

    I have tons and tons of questions, especially when it comes to your mist-a-matic, and the misting 'house' that you built....

    Certainly, any misting system here will need protection from the wind. We get lots of it here, especially in the afternoon. We also gets lots of heavy rain, almost every day in the afternoon when the thunderstorms from the Gulf start brewing (I hear thunder now), so I don't want an outdoor misting system running when it doesn't need to run nor is it good to have the wind blowing the mist away from cuttings.

    I am also looking for a way to grow my seedlings without them being drowned by the heavy rains, only to suffer from lack of rain for several days.

    Any thoughts on that?

    Thanks, in advance!
    Ann B.
    Zone 9a
    Gulf Coast


  5. #5
    Join Date
    Feb 2002
    Location
    Surrey, BC, Canada
    Posts
    221

    Mist setup

    It sure is a learning experience, and always ongoing.

    I started out misting in the open in full sun. Some stuff rooted fine, many things had problems with the bright sun.

    Without cover, straight sand is safest, coz it will drain quickly even with a long rain event...no problem for the cutting.

    I have found peat/perlite 50/50 the best for the clematis I'm doing, but that is just one plant with my covered (70% overwintering poly) area with bottom heat cable set at 20C. I think it's good to try many options if you're doing a lot of one plant. This year I actually added a good % of vermicompost, straight from the bag...cuttings have done well and esp. grow on better once they are rooted.

    Pure perlite didn't work well for me, nor did plug trays. The rooted cuttings did not pop out in a nice, undisturbed plug for me, something like peat was needed to make a nice root mass that would hold together...with this one plant and it's type of roots. Also, if you're not right on top of watering, the cells of plug trays can get dry in some spots, and maybe tend to dry out faster overall.

    I'm real happy with deep undivided flats, and filling a whole bench with media like some of the big rhodo propagators do is tempting also. More even water control, and lots of room for roots to ramble if I'm not potting them up right away (like right now, lazy me, got quite a few that would do better potted up...)

    Ann your rainy summer weather always fascinates me, having grown up in an area that rains almost daily from midOct to some time in Feb or March, and no appreciable rain thru most summers. I can see the problem trying to leave seedling flats outdoors when it can pour torrentially on them, or bake them other times. Need more control at that size, and in such shallow containers that won't tend to drain like older plants in deeper containers. I have seedling plug trays right outside, but with no rain since I can remember, it's like total control...any water these little guys get is from my hose!

    How can you cover your little guys without cooking them...and it would be nice to take advantage of some of the natural rain, I still think stuff grows better in rain water than my tap water

    Glen in BC

  6. #6
    Join Date
    Aug 2001
    Location
    Zone 9a - Gulf Coast
    Posts
    9,934
    Glen,

    I grew up here, and even though part of my younger life was spent in Palacios, TX, this is indeed what I consider to be home.

    I am not sure what makes us different, and why we are normally the second highest in rain most years, but it is something I guess that I have just learned as 'the way it is'....

    As I ventured into my life with Landspro, I began to learn more and more from the many friends I have made about the differences in climates, and thus, the difference in propagating techniques...

    Not only that, but I realize the differences in natural resources, like Shepp's coarse sand. To me that is coase gravel, to him, it is coarse sand...

    We can be so close with the internet, but I am reminded every moment of the day how different our worlds are when it comes to gardening.

    I can tell you that where my Mom lives, where I grew up, is so very different from where I am now and it is only 15 miiles away!

    Go figure! But still, we can learn so very much from each others' experiences!

    And I have learned more from all of you than you will ever know!

    I thank you all for that!
    Ann B.
    Zone 9a
    Gulf Coast


  7. #7
    Join Date
    Dec 2002
    Location
    northeast Tennessee
    Posts
    1,703
    Glen, We float our plug trays in kiddie pools or a special lined bed we made in the greenhouse. This keeps them from drying out. So far it has worked well for us. This is how most tobacco plants are started now here in this part of the south.A friend of mine at the farmers market grows a lot of annuals ,bedding plants and a few herbs this way. He just brings the float trays and pulls the plugs that people want and sells them for $2./dozen. He makes a lot of money this way.
    tennessee sue

  8. #8
    Join Date
    Feb 2002
    Posts
    598
    Ann,

    Iím not sure what % sun screen I have, it was free so I took it.

    Iíve already considered a couple of alterations to make. One being a rain proof top of some sort. Maybe just some translucent plastic to break the fall of the rain. With the shade cloth on the sides, there is not much problem with the rain blowing in. While it does allow air exchange, it cuts down on the wind and drift enough to solve that problem.

    As I said above, the mist controller I am using, only comes on when itís needed to wet the leaves. The humidity level here today was in the area of 80-90%, so the mist system rarely came on. I was out there for about an hour and it never came on. If you will take another look at the plumbing, you can see an alternate manual valve to bypass the solenoid valve in case of power failure. I will not be using the mist system during the winter or early spring so it will be a simple matter of unplugging the power, and using the manual valve to gently wet seed flats. But with your fall seeds, I don't know if they would get too much water or not??

    Glen,
    I am using cells for my cuttings because of the limited space I have, and the fact that these Viburnum really resist being transplanted until they are a year old. With a mix of vermiculite/perlite/peat, I get good drainage, and just enough body to slip the cell out and directly into a very wet 6" pot that can stay outside for the rest of the year. Hopefully they will never know they have been moved. Of course some of the other plants could be done in undivided flats, but I never plan to leave them in long enough for the spreading roots to be a big problem. With the 2" cells I can see the developing roots coming out the bottom. Iím trying to get them rooted, potted, and acclimated to the elements as soon as possible so they can spend the winter outside.
    Tom W
    Aching Back Farm

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