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ideas for keeping seedlings warm?  RSS feed

 
Kelda Miller
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As I'm thinking about seed orders and what I'd like spring to look like in the garden, I realize that my starts have always kind of *sucked* because I don't have bottom heat. I poke around at my farmer-friend's place, and they've all got heating pads under their starts.

Whatever, but after enough years of this, I just want some robust seedlings in springtime! Too much to ask?

Here are some ideas:
*manure composting below the trays
*sand
*sand + water bottle (heat up the sand, then put the tray on that)
*hot water underneath, like dirty dish water? or would that kind of heat make them more vulnerable to frost by not being cautious?

I have some hoophouses that get sun, but aren't sealed super tight. So they're really only hot when everything else is warm. I'm looking for a method that will keep things warm when everything else is cold.

Has anyone had any luck with non-electric seedling heat?

 
Leah Sattler
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I have always used 'warm spots'. my water heater is under my kitchen cabinet and thatspot of counter directly over it is a favorite place. on top of the microwave (that gets used some) works too to get them to germinate.

I like the idea of using a compost/manure pile somehow. watching the steam rise off a large manure pile in the winter is all the evidence I would need that it would work. when I was a kid I would go dig a shallow hole in the manure pile to sit in and warm up in the middle  of winter. (this was horse manure so it doesn't stink so bad even when still fresh)
 
Susan Monroe
Posts: 1093
Location: Western WA
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I have thought about that for about 15 years and still haven't come up with anything stable that won't kill the seedlings.

Manure:  the English build what they call 'hot beds' with manure.  I just looked it up and the instructions say to dig a 2 ft deep hole (deeper if you have to add gravel in the bottom because you have poor natural drainage), then add an 18" layer of horse manure mixed with straw, then add 6" of good soil.  The drawing looks like it has wooden sides all the way down to the bottom (probably to help contain the heat), and a glass cover tilted toward the south.  They say you might want  to cover with some kind of insulation at night

Compost:  I read some years back (Organic Gardening Mag, I think) where a guy wanted to heat his greenhouse with compost.  The ammonia gas it gave off killed all his plants.  He was going to try it again and use something like PVC or chimney stove pipe to vent the confined gasses, but I don't know how that turned out.

Some people get metal 55-gallon drums and fill them with water and paint them flat black, and use them in a greenhouse.  They absorb heat from the sun during the day and release it at night.  It seems you would need some decent insulation or a lot of barrels for a plastic greenhouse.  It might also be possible to join this with a solar hot water heater, with the barrels as storage.

Some people have used discarded waterbed heaters as heat mats indoors, but you still need enough decent light after the seeds sprout.

Due to certain recent posts, what would you think about a rocket stove as a greenhouse heater?

My house is too cold and too dark to use anything but a heat mat (too small, really) and a shop light.  Added to that, I have to cover the entire front of the cubbyhole in the laundry room where I start my plants with chicken wire  because one of my cats jumps up there and bites the tops of the seedlings off, and pulls up the rest.

If anyone finds perfection, PLEASE POST!

Sue
 
Leah Sattler
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Susan Monroe wrote:


If anyone finds perfection, PLEASE POST!

Sue


ditto. honestly I buy most of my seedlings. I have started roma tomatoes and cabbage successfully (as well as some squash but I think they did better just planting the seeds out) I have the cat problem too, that is why the top of the fridge is often where mine end up. I hang a grow light from the ceiling on chains to keep the light within an inch or so of the plants. last year I started a few dozen tomatoes, they were 4-5 inches high when I decided to start setting them outside a bit to acclimate them to full sun. I forgot them out one night and they all froze   I was so mad at myself,
 
Susan Monroe
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Location: Western WA
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Any cold-weather crop like cabbages, spinach, peas, etc, can be started outside NOW.  Well, if it isn't snowing.  I've got some stuff already started and sitting out on an old door supported by two sawhorses.  Just keep them watered if we go too long without rain.

Winter Sowing REALLY works.  Except for the warmth-loving plants like the tomato family (peppers, eggplant), beans and the squashes, etc.  Those are the ones that get the mat/light space these days.

Sue
 
Brenda Groth
pollinator
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Location: North Central Michigan
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the top of a refrigerator or freezer really works well, as there is always some heat , although the space is small, and if you want it to even work better pop a flourescent light over them up there and they'll be nice and short and stocky, rather than gagly

This year I have a nearly enclosed in glass and plexi front porch that faces south..just little..8x12..but I'm hopeing to start seedlings out there when temps stabilize above zero for a while..it stays about 10 degrees warmer than outside temps and gets sun if there is sun...but the bottom heat thing would be a problem out there..too..guess i'll have to think that through as well
 
Kelda Miller
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cool, so now my ideas are:

*would goat/chicken poo be too hot? i wonder if i can adjust the thickness of the pile to adjust the heat? (how much heat can 1 inch of chicken poo really give out in a day?)

*okay okay, a waterbed heater would be freakin' awesome. yes, it uses electricity and all, but i just want to have a successful year at growing strong starts, just so i don't get all depressed about it. but i'm not going to buy a handful of heat pads for $30 a pop.

I have a friend who used the waterbed heater in the waterbed frame, in the greenhouse, which leads to the obvious question: why not the water too?? there's your thermal mass.

*also, thanks for the funky ideas and also the feedback that starts are sometimes just hard. my friends who buy starts have 1/20th the work I do in the spring, and I don't really want to buy, but it would actually be so worth it with all the failures i've made.

*I'll start those winter crops as mentioned above. I knew that peas could sprout in weather like this, but for some reason I hadn't thought that brassicas could.

*I'll keep you posted, and you guys do the same
 
Leah Sattler
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you will need quite a bit bigger pile than an inch or so. I would go with a real pile, several feet high so you can dig a trough and set them in it to protect the tops. I don't think you have to worry about getting them too hot that way. they would have to be buried to get too hot. the top of a big pile of manure ( 10' ) is just pleasantly warm on top, its in the middle that it gets screaming hot, thats why turning it makes it compost so much faster.

although I know you can techinically plant out cabbages and such right now in reality it doesn't work well, for me at least.
peas and cabbages are best planted in the middle of march here, otherwise they don't grow fast and vigourous enough to be hardy. its seems they need to be able to really get after it or they are always stunted and disease ridden. the peas are ready in 60 days and are usually mostly finished by the time hot weather rolls around. cabbage though takes jsut a bit too long and it gets too hot in june for them so they need to be started a bit first in my experience in this area. they just don't get going fast enough to be ready before they are unhappy cause its 90 something degrees.
 
Susan Monroe
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Location: Western WA
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Leah, your cold to hot weather must be a real pain.  That's one thing we don't have here in WA!  We waited all summer for some hot weather last year, and then fall came!

Sue
 
Leah Sattler
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it is a pain. there is an oft repeated saying around here.."if you don't like the weather just wait a minute"

the record high for this date is 86* the record low is 0*
 
Susan Monroe
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Location: Western WA
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And they were three days apart, right?

I keep thinking that flat black-painted 55-gallon metal drums could somehow keep plants warm.  But what to put around them that isn't a whole greenhouse?

Sue
 
Leah Sattler
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I wonder if you could just dig a hole and put glass on top? sort of like a mini psp green house. that would take advantage of the natural sun which is oh so much better than artificial and if you surrounded the area with black plastic you could use the mass of the surrounding earth to retain the heat from the day.
 
Susan Monroe
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Location: Western WA
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Taking your idea a step further, how about a hole in the ground, with a black-painted, water-filled drum on the north side of the hole (or a bunch of large black-painted rocks), and the plants on the south side of the hole, with glass over it?  Of course, you would probably have to raise the glass every day to prevent the seedlings from overheating...

Sue
 
Dave Boehnlein
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Location: Orcas Island, WA
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We had some limited success with a manure bottom heat set up a couple years ago. We made a ring of haybales and filled it in with stable litter (horse poo + sawdust). On top of the poo we put a few inches of sand and on top of that we set seedling trays. Over the whole operation we put an old window that could be removed on sunny days.

The temperature control worked fine. However, the cuttings we put in failed due to human error. We forgot to remove the window on a really hot day.

Before you actually put any plants in you would want to check temps with a soil thermometer & an air thermometer (a recording thermometer would be even better). When you're sure you've got enough sand over the manure you could put seeded trays in and go for it. Make sure you manage the window, though!

The picture below shows a couple of our interns making cuttings to put into the 'hot bed' (which they're sitting on). The window can be seen on the right.

Dave
manure_bottom_heat.jpg
[Thumbnail for manure_bottom_heat.jpg]
 
Susan Monroe
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Location: Western WA
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"I have a friend who used the waterbed heater in the waterbed frame, in the greenhouse, which leads to the obvious question: why not the water too?? there's your thermal mass."

I believe I read of someone who did, or was going to try, putting a waterbed mattress in the greenhouse w/o the heater.  He was adding black dye to the water, to absorb heat.

I also read of someone using those older fat Christmas lights to keep plants from freezing, although I don't know if it would keep them WARM.

And there is also using animal body heat.  Have chickens or rabbits confined to the floor of the greenhouse (insulated with straw) and have shelves above them for the plants.  Chickens produce something like 11 Btus per chicken per hour (or something like that), and heat rises.  Size of the greenhouse and the number of chickens would be crucial, of course.

Sue
 
Arrow Durfee
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I use heating pads, not the ones from green house supply, but ones for humans from a drug store or or walmart or somewhere and are much less expensive. They get much hotter. I fix that by putting a few layers of towels over then under the trays.

Look for old heating pads at garage sales and used used stores. Another option Ive considered is an electric blanket.
 
Jordan Lowery
pollinator
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Location: zone 7
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I moved farms but at my last place I had a good setup.

Inside the greenhouse was a long bench, this bench had a lip on all sides that went up an additional 2". The bench top had 1/2" tubing zig zaging through the top. In one end and eventually out the other. and then the tubing was buried with Sand. As it came out the other side it was purposely left exposed and not insulated.

Now here's the interesting part I heated it with two methods it was hooked up to a solar collector( black box with tubing on inside with glass over top, again in one end out the other. The end going out went onto the sand bed the tube coming out of the sand bed went into the bottom of the collector. This way the whole process acted on a thermosiphon. So there was no pumps involved. It heated up the mass in the day and released it at night. Now if it was going to be cold like really cold I'd make a mini hoop tunnel over the bench to keep that heat in one area.

Now I first learned oh guess what it's not always sunny, so I made the option of hooking it up to a compost hot water system. Like the one In pauls video. When done with a good size pile and the right compost ratio you also get that. Awesome thermosiphon effect for the pumpless system.

It worked excellent and I was germinating peppers and tomatoes in January with outside temps in the high teens/low twenties. The germination bench with mini hoop tunnel was around 65 at night and about 80 during the day.

I plan to rebuild the system this fall for next year, been too busy doing earthworks to make building it this year worth it.

-
 
John Polk
steward
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Years ago, I was tight on money, and wanted to start some seeds.
At the big box garden shop, they had those heating pads, but I couldn't justify $40 for something I would only use a couple of weeks. On the way home, I stopped @ a yard sale, and this lady had an old crock pot. I think I paid $1 or $2 for it. Filled it with potting soil, and put it on the "Stay Warm" setting. Worked great!

 
Brenda Groth
pollinator
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Location: North Central Michigan
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i also use the top of my frig and freezer for seedlings, until they get tall enough to require sunshine
 
allen lumley
pollinator
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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If someone else noticed and spoke about a few minor errors that snuck in when Susan was trying to be brief, Then here they are again ! The manure pit,works well
surrounded by 'square' hay bails and covered with storm windows, getting the temperature just right requires the type of Large Round Thermometers that can be
read from a distance and watched carefully. Taking the storm windows ompletely oof may be neccesary !There was a comment about putting gravel in the bottom of
the pit if the soil does not drain well. This would work if you were able to dig down through or past the poor draining soil into better draining soil, A small amount of our
heavy soil can make a low wall to promote drainage away from the Manure pit ! See Daves picture of a manure/compost pit above.

I have never heard of a compost pit or another compost heating project killing off Seedlings due to high ammonia release shoveling the compost into a compost pit
should give you a nose full of the potential for that problem ! Has any body else been personally exposed to this problem ?

For the Good, Future Good of our Crafts ! Be safe, keep warm ! As always, your comments and questions are welcome and Solicited ! PYRO-LOGICALLY Big AL !
 
Kelly King
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Location: North West Vermont - near Saxon Hill
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Haven't done it yet, but I have been thinking through a system for heating plant-starting benches overnight with the water from the dishwasher. It kills me to think of all that heat we've paid to make, ending up in our septic system. We have a closed in back porch which works as a solar collector on sunny days in the winter, but even in the spring doesn't stay above freezing at night. My idea is to have a diverter that runs the water from the dishwasher into some kind of tanks (old hotwater heaters on their sides??) that will slowly release the heat into the plants above and the room in general. Then, when the water is cooled (or just before then next dishwasher run) the water is let out into the greywater system in the yard. We can adjust when we run the dishwasher to have the heat focused in the evenings when we need it. I'm not sure it will actually work for starting plants out there... it still gets to be 10 below here in late February . But it would definitely extend the "shoulder season" when stuff can be on the porch in early spring or late fall. I might try to think of some other way to use the heat from the dishwasher water inside under planting benches. Maybe just have a diverter so I can fill a few 5 gallon buckets and put them under the tables I start plants on ....


If I get to it this year I'll report back... with pictures.

-Kelly
 
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