Good idea or bad idea?
 

I just started my first tomato seeds in the 20 row seed starting trays.

Now, I've seen that they are supposedly unsuitable for use on heating mats, because the small amount of mix in the rows would dry out too quickly. So here is my idea:

Again, I'm sticking them on the good 'ol Directv box. I've set the seed starting trays inside a solid tray, and covered it with plastic wrap. The seed starting trays are shallow, so there is a big gap between the bottom of the seed starting tray and the base of the solid tray.

What I thought seemed a good idea was to put some water in the bottom of the tray (not actually touching the seed starting tray). My theory is that the water will get warm and give off some heat. Plus, the water in the bottom should hopefully condense on the plastic, and generally make a warm moist environment so that the mix won't dry out.

Any reason this is a bad idea?

(yes, I know, don't give the directv box a bath)

Instead of water, maybe just more seed starting mix? I worry about water in proximity to electronics.

Could I suppose.

I know what you mean about the water, but I just can't see a way that 1/4-1/2" of water could escape from that solid tray. I don't have children or anything who would mess with it.

Another vote for bad idea...do you have any small strips of wood that you could use to put a small bit of distance between the solid tray and the seedling tray, or between the solid tray and the tv box?

There's already a bunch of space between the solid tray and the seedling tray. That's why I thought the water would be fine down there, as there would be a layer of water, then a layer of air, then the seedling tray. So the water wouldn't touch anything (tv box or seedling tray). It'd just get warm, and hopefully keep stuff moist.

If there's already a space so the non-heat-resistant tray is protected, I'm not sure why you feel the need to fill the space. If the soil is moist enough when you put the plastic over it, that should keep things moist enough without adding more water to the set-up, no? Less water around anything electrical, the better.

Because in one of these threads discussing the seed starting row trays, the reason that they are not suitable for heat pads is because the mix dries out too fast, not because the plastic won't tolerate it. The drying out too fast is the problem I am trying to solve.

I know water/electric is heebie-jeebie, but I just can't think of a way the two would get together.

Oops...need to work on my reading comprehension...don't know how I got that idea.:oops:

I've never used those trays but I've seen them and understand how they'd dry out quickly if uncovered; I don't see how once you've covered moist soil with plastic wrap that they're going to get dry so quickly. The water evaporates, recondenses on the plastic and then falls back onto the soil surface, right? I use domes sometimes and plastic other times and never have to water until I remove those for good. Since you plan to use a really gentle heat source, I'd be surprised if there's a problem. But since I've never used them, what do I know?:?

You need advice from the more experienced.:yes:

I don't know how they would dry out either - but I would have thought when saying "not suitable for heat mats" that the manufacturer would have presumed they'd be covered, and dry out anyway. I dunno.

Actually, now that I think about it, my pepper seeds in this media did require extra water while germinating, even with the plastic on them. How, I don't know - but the did get a little drier from time to time.

There really isn't a lot of mix in these little rows, and I am using a soil-less mix.

I have done similar things to that. I prefer the clear dome lids. Sometimes with bottom heat the small cells dry from the bottom up, which can be a bit misleading. It works best if the cell tray sits flat on the undertray, but if the water is to disperse the heat you should be fine with it being suspended. [I]

-From someone who has used a 400 watt block heater as a heat source for 4 seed trays and not burnt down the house. [/I]

I no longer use that method.

Anyway, heat mats have hot spots, so it can be a pain with (200 cell?) trays. Big growers use them on [COLOR=Red][B]heated floors[/B][COLOR=Black] (think: a few acres worth).[/COLOR][/COLOR][COLOR=Red][COLOR=Black] They do it with 500 cell trays, too. That's some tiny cells.[/COLOR][/COLOR][COLOR=Red][COLOR=Black] I think the cable box is a pretty clever second choice.

[URL]http://ohioline.osu.edu/aex-fact/0801.html[/URL]

[URL]http://asae.frymulti.com/abstract.asp?aid=19909&t=2[/URL]
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If you have a gas oven, I would suggest putting them in there with only the pilot light supplying heat (which is what I do). Otherwise I'd place them on top of a furnace/ or your hot water heater/ or even the refrigerator. All supply heat without having to worry about water and electricity.
Just a small leak could cause big headaches.
I also mist mine daily to keep from drying out. I just planted a tray late yesterday evening and they're resting nicely in the oven. Enjoy!
Camo

Unfortunately, I don't have a gas oven. And the top of the fridge isn't really warm - I would have thought so, but it isn't.
I did think of the heating duct, but it isn't warm all the time, but seemed like it might be too hot when the heat is running.
So far I haven't killed the 'ol DirecTV box, but this is a good reminder that I need to go check on those seeds.

Edit: Well I guess they liked it - good thing I just checked, a bunch of them are up in only 3 days. Cool.

Pilot light...I was thinking about this, we have gas ovens, but the last one I saw with a pilot light had to have been an old one in a house we were in in the 80s. Most newer gas ovens around now will have an electronic ignition for the oven and the stovetop burners. So many don't have that option even with a gas oven. I went ahead and got a heat mat and a thermostat, seems to be working well.

Can something be placed between the heating pad and the tray to reduce the heat? Like a towel or something similar?

The heat mats made for the purpose are limited in power. [URL="http://www.amazon.com/gp/product/B0001WV010"]The one for 1 flat, that I got is 17 watts[/URL] It's supposed to raise temp 10-20 degrees. Using it with [URL="http://www.amazon.com/gp/product/B000NZZG3S"]a thermostat[/URL], you put the probe in the mix, or you could put it under the seedling tray, in the solid tray, if you are worried about the solid tray overheating or something. The thermostat can be set to whatever temperature you want.
If that amount of heat dries out the mix too fast, then you need to change something else.