Heat Propagator - Germination Station

Maquiaveli(8b)December 12, 2012

Hi, I'm totally new to growing plants and trees from seed and purchased a heat mat germination station (actually, it's one of these cheap hydrofarm products you can buy on Amazon) to get some seeds going indoors. I have a few questions I thought you learned folks could help me out with:

1. I'm finding that my germination medium (peat moss/perlite) is drying out even though the propagator has a 2" plastic cover over it to retain moisture. I understand that seeds generally need moisture (but not wetness) to germinate. What's the best way to keep this kind of mixture appropriately moist throughout? I spray water over the mixture every other day, but the peat on top absorbs the water and it's hard to get the mixture consistently moist all the way through. Too much water and it becomes dripping wet. I'm wondering if a different germination material is better when using a propagator--something that is easier to keep sufficiently moist throughout. Any thoughts?

2. I tried laying plastic over the seed pods to keep the moisture in. But I'm reading elsewhere that this would likely increase mold and other undesirable effects. I'm not sure if this is a good idea or not. Anyone have any experience with this?

3. How warm is too warm for seeds? With the 2" plastic cover, the temperature under the dome is about 28C. With plastic directly covering the seed pods, the temperature reaches about 34C. I suspect the air temperature is warmer than the soil temperature, but is 34C too warm?

If it helps, 'm trying to germinate a number of different seeds (ensete ventricosum, musa cheesmanii, musa ornata, various palms, among other tropical plants/trees).

Sorry for the long-winded questions. I'd greatly appreciate any advice anyone has to offer.

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Hi Maquiaveli and welcome to GardenWeb!

Regarding the problem of your germination medium drying out so fast, it's important that the medium be properly moistened before you ever add it to the seed trays (or whatever you're using). Using some kind of clean container, the medium and water should be thoroughly mixed until evenly moist (but not dripping wet) throughout - then added to the seed trays. If you didn't do that and instead are trying to moisten the medium by spraying the top, that's probably your problem.

I've never tried to germinate the seeds of tropical plants so I'm not familiar with the proper germinating temperatures. However, 28C does sound a little warm to me (much less 34C). Those warmer temperatures are no doubt contributing to the drying of the medium. Another possibility is that the medium has too much perlite mixed with it.

Regarding the plastic over the seeds, I've never done that but it does not sound like a good idea to me ... too wet, too hot, mold etc.


This post was edited by art33 on Wed, Dec 19, 12 at 22:08

    Bookmark   December 13, 2012 at 12:19PM
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Hi, art33:

Thanks for your response. I moistened the medium as you describe, i.e., prior to putting in in the seed trays, etc. There's actually not much perlite in the mix, either. I can only guess that the heat mat is just too warm.

Based on your advice, however, I have decided to scrap the plastic sheet idea.


    Bookmark   December 14, 2012 at 7:59AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Did you also buy the thermostat control for the heat pad? It is difficult to control without the separate thermostat.

Otherwise it can help to create a small space between the mat and the bottom of the trays. EX: assuming the seed trays are the standard 1020 trays small wood shims or scrap 1/2" plastic strips work well as spacers placed on the mat. Think outside the box to try to create a 1/2-3/4" space.

If the growing medium was well wetted before filling the trays then a fine-hole sprinkling can of some sort works well to maintain the moisture level - misting really isn't enough.

Hope this helps.


    Bookmark   December 14, 2012 at 11:53AM
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Hi, Dave:

Thanks for responding. I don't have a thermostat, but I've read elsewhere that it's a really good idea to utilise one for controlling the temperature, as you say. I am looking into it.

As far as I can tell, the seed tray is not actually touching the bottom of outer tray (and so there is some small space between the heat mat the trays). I like your idea of raising the trays. I will do that. I will also obtain a small sprinkling can to water the medium. It will be a lot easier than using the mister. Seems obvious, but being new to all of this, I just never thought of it.

On a related note, I'm happy to report that one of my moso bamboo seeds sprouted and is now removed from the tray and growing on its own. Hopefully, this is an indication that conditions weren't too bad in there.



    Bookmark   December 17, 2012 at 2:33AM
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