This is very good. Methodical and thorough. You deserve a lot more attention.

This was fascinating! Based on everything learned, I would call this fail a success. On the subject of utilizing the heat generated by decomposition, I saw a food show once where they were cooking food inside a compost bin. Anyhoo, thanks for sharing.

I admire your hard work and all of the detailed observation and problem solving. I am sorry the project didn’t quite work, but you and everyone watching learned so much. Thank you for what you do!

Hi, yes, compost gases damage the roots / leaves and the plant may die. In the initial stage of decomposition, microorganisms begin to settle. Part of the carbon (C) from compost is converted into microbial biomass, part of it is released into the atmosphere as CO2 in the process of respiration. This releases nutrients, especially nitrogen (N), phosphorus (P) and sulfur (S). N and S seem to be the main reason for this problem, because the symptoms are very similar when we overdose plants with fertilizer. Next time, use a barrier on top of the compost, a polyethylene plate / foil, this will transfer heat and retain gases to reach the plants. I hope this helps you. Greetings.

I love how you experiment and show your results rather than just repeating endless gardening tropes like many youtube channels. Thanks for sharing this Bruce, I had been thinking of using this method myself, but now realise I'll have to make some adjustments.

Very interesting. Thank you.

Gosh, who would have thought? Would you not have smelt the ammonia if it was in high enough concentration to damage the leaves? Glad the plants got back on track. So pleased when you post these more scientific videos. It adds another view for those of us 'amateur' growers. Happy sowing, growing and harvesting

I like the plastic sheet idea.

Thanks! I love it that you have the courage to publish some negative results, including all your thoughts about what went wrong. Everyone can learn from this. More KZfaqrs need to follow your example.

Great to hear that the plants not only survived but are thriving now, at the beginning I was sure they are write-off. I am also relying on thermal mass of black bought-in compost in my polytunnel together with fleece and its working surprisingly well when some frosts come. Surprisingly the only damage I got in polytunnel are kohlrabi where only one variety out of six is going into the flowering stage. Supposedly longer periods around 8-10 C are what can cause this, not the frost :)

Interesting discovery. I came to the same conclusion with the ammonia, when I started a new no dig garden with fresh horse manure last spring. It killed off all the leaves on my neighbor's ivy which she has growing on the property line. I also had a hard time growing anything there for at least 6 months. Since most of the ivy does not root on my side of the garden I also came to the conclusion that ammonia gas must have caused the damage. I would not have expected this effect with grass clippings though. But it makes sense. In the end horse manure is basically grass. How other growers can grow tender seedlings on top of a pile of horse manure inside a green house is beyond me. If it kills ivy in open air outside. I'm sure it would kill anything else inside the green house too. Great video, once more.

you can also use the heat of the earth. I don't know the english name but in french it's 'puits canadien' (canadien well ?? maybe you know ... it's from your country ^^). I make mine by putting a long tube (pvc gutter) in the soil (around 75cm deep) for almost all the length of my green house with a small fan a one end (from an old PC, run with a battery and a solar panel). the air coming out is around 10°c in winter

Way back in the 1950s Dad used a similar method for his cold frame. He dug a deep large hole outside with old pipes in the hole rising and running around the walls of the frame, there was an open water tub in the frame which kept the water in the pipes topped up and could be added to at any time, sometimes even with a kettle of boiling water. Then he filled the hole with the manure, grass and other stuff to be composted covered the lot with wood slats and an old carpet. Heat naturally rised from the hole into the frame. As winter went on he would add more stuff into the top of the hole. We had fresh greens and early tomatoes and cucumbers at a time they weren't available in the local shops. So I think your shower gave the idea, now to think how you can use the natural law of rising heat to save pumping etc. (taties were always grown in the compost in that hole after its use for the frame was over, and in autumn spread on the garden. To leave the hole ready for refilling)

if the problem was compost offgassing, you could try layering finished compost on top of the active pile. ammonia gas is very soluble in water so it should be captured by moist compost and then turned into nitrate by bacteria eventually. I think when hotbeds are discussed, people usually advise to top them with compost or soil, maybe this is why?

Thank You, this is very challenging, great presentation!!

Thanks for the thorough video. I'm glad you averted disaster. I heat a small ( just under 400 cubic feet) green house with about a cubic yard of compost. Ive been doing this for the last 5 years, but the last 2 years have been very difficult to find horse manure and coffee grounds in my local area, and finding alternate materials in the winter months in my local area within Vancouver BC has proven a challenge. I had no problems withstanding temperatures of down to -8c overnight, though once it dropped to below -10 I did sufferer some light frost damage. During the coldest nights I also used a thin single layer of lightweight remay. The last 2 winters I struggled though to produce enough heat during the coldest months simply because I couldn't find appropriate compostable materials in my local area. Though once things outside warmed up by late March I was able to use greens etc. So the quest now is to stock pile enough material ( compost seems to produce enough heat for about 5-6 weeks then needs to be refurbished etc.) to get me through an entire winter from November through April. I'll have to keep the noxious gas issue in mind moving forward as I've never experienced it.

Another amazing vlog!

A very interesting and honest video . Thanks Bruce. Like others who have commented, I don’t think that this was a failure as you learned so much from this. It would be interesting to see if a piped water system from the decomposing material could run underground soil warming for the plants. Thanks again.

Thank you for the video

Sorry for the fail. Lots of meticulous hard work and science you put into this effort. Thanks for thinking of the viewer's. Many, including myself work from fails and successful methods.

I know I left a comment before about using compost heat for warming plants. I think this definitely was a success. Only a failure if you didn't learn anything. I was surprised that the potato plants give off heat. I will have to keep that in mind. That makes grow bags portable space heaters. I too was thinking about the sheet over the pile to divert the gasses. A metal pan may also work, and conduct more heat. From my Computer days, I recall that the transfer of heat requires, contact, surface area, flow, and turbulence. That's why Computer heat sinks have metal fins, to increase surface area and turbulence. I don't know of anything that would be a bunch of metal spikes, but the wire rack could be conductive if placed in the decomposition. or just put potato grow backs on the bottom of two shelves and let a little heat rise. Or increase ventilation. Anyways, I thank you for sharing, we all have to keep learning. PS, now I'm imagining tomatoes growing on your shower compost pile. Because it had a cow panel outside, and the gasses would rise up out the middle.

It's great to have someone trying out things before you, thank you for the information. You've got a new subscriber!

A great experiment! The point of the exercise. Thanks for sharing the details.

Great content, just found it. You're style and quality of info etc is right up my alley.

Woow. A very important lesson learned. Thanks.

This has to be my favorite gardening channel and I couldn't to wonder why it has more subs than it does. Personally I like that things are shown with actual data to back them up. Quite often, a lot of the proposed methods are claimed to be the best way to plant or grow but usually fail to provide any evidence for it.

I suggest you take a look at passive solar greenhouses. In Holland, my far from perfect interpretation resulted in a frost free GH.

Can't wait for the tomato variety recap this summer!

Maybe have an active heat pump system from a compost pile? Have a closed-loop water cable go through the compost and then to an area where your plants are under fleece? That would take care of the outgassing problem from the compost while still receiving its heat. Either way I love your scientific approach. It was very interesting to see the temperature graphs. I have also had some fails this year with contaminants in my seed-starting setup but through the problems I now have better procedures to keep things clean. Keep up the great work!

Another great video, I really like your ideas and follow through and analysis of results. I think you identified the most correct cause(s) of issues with using free compost heat. By laying out the idea and issues so clearly you have enabled others to think about ways around those issues. I wonder if methane could also be building up in your tunnels, if so it could present a serious fire/explosion hazard. Hopefully someone can run the numbers on the BTU potential of a hot compost bed and determine if the potential would make it worth using some sort of liquid or air heat exchange system. Thanks for your hard work doing and reporting your projects.

amazing video and interesting findings. would be interesting to get additional data to assess hot beds further

I'd go with what you already know how to do, and that is the pile used to make hot shower water. However instead of water put air through the plastic pipe. And if you build it carefully, the heated air would move through the pipe on its own sucking cold air in from a bottom inlet at one end in the tunnel and leaving the pipe at a higher point on the opposite side giving you a flow of air through your tunnel. Solves both the heat issue and the poisonous gasses issue. A passive system requiring no electricity. Might even be possible with your cold frame setup!

Surprisingly Bruce, the plants look really good. How about completely wrapping the compost pile in polyethene and using it as a kind of hot container which is enclosed? Of course, it may give off too much heat then. That was a great experiment. I would never have thought of ammonia like that, and doing that kind of damage, what a shock it must have been. The plants are certainly a lot bigger than mine though 🙂. It does show how tomato plants can, however, be quite forgiving.

Top YT channel. Highly recommend!

Great problem solving! Nice to see every possible variable being considered. Excellent description of the situation, thanks for sharing.

Thank you for sharing your experiences like this. I feel inspired to try to also teach by exemplary learning.

I've found starting my tomato plants 4 weeks before last frost is plenty of time and I get tomatoes by July. I start them in small pots in a window and transplant them to.bigger pots after 2 weeks and move them to a cold frame about April 15th. Then may 15 I plant them out and bury them deep and they really take off. I have had to cover them with fleece for very cold weather but it's better then in the past when I've damaged my plants by starting them too early. I am planning on using compost heat in my greenhouse for fall crops this year. Rocks can also be used to hold heat at night. Gardening is always a learning experience that's for sure.

I always love your videos.

Excellent video, as always.

We've had this issue before with our hot beds. There was so much amonia i the air that you couldn't breathe. Everything in the tunnel died, apart from the toms. We still use hotbeds but we put 50-70mm of finished compost over the heaps and this seems to trap the gasses inside the piles. Still works great. TBH we're moving away from hot boxes as they're so much work and not consistent enough for our needs.

thank you for sharing your experience, very interesting & much to glean from your efforts! Bless you & your work, and I am very sorry for your loss!

subscribed!! this was so informative. thank you so much for the thorough explanation!!

I’m so glad your tomatoes recovered! They look amazing!👍🏼

I think you may already have the solution between your cable heated bench and your shower. could you run the out feed of the shower compost bin around a bench (similar to underfloor heating in a home) and then return to the bottom of your shower compost bin in a loop. the convection current should make the water flow provided the bench is higher than the bin. That way you get the heat but not the off-gases. it's a really interesting experiment - thank you for sharing

Thank you, that is really good information and helpful to know. We have a massive tunnel house to plant out in spring this year and I was considering a compost heater to get them started. So this video was very timely

Thank you, fascinating stuff.

how do you fund all these projects and what do you do with the produce. im in dunedin new zealand and i think we have the same kind of weather. i like your videos they are very helpful

Hi RED Garden just wanted to mention its ethylene that typically is the concerning gas and you have to separate the heat from the gases you can put the compost pile outside the greenhouse and have it heat the nursery through the wall

Reminds me of the time i was using a hot bed made with straw bales and windows to get a jump start. All was going well until a fungus and or mold hit the transplants. Ventilation was the solution, however i needed it automated since my schedule was so variable. Mabey you could turn me on to ways this could be done inexpensively.

Good info.

A very useful video. I did something similar on a smaller scale with heavy duty rubble bags stuffed with grass cuttings and hay + a sprinkle of 'activator' under an area of slatted polytunnel staging with a twin wall polycarbonate lidded box sitting on top that had a wall of water filled 2L PET around the internal perimeter, and it kept my most tender plants safe. I chose bags so I could adjust the amount of warmth, swop them as they cooled down, and see more easily if vermin were getting in, plus I had a nagging suspicion that harmful gases might be emitted. Good to see visual confirmation that my tunnel was benefitting from all the bags of early potatoes and water containers I had in there when there were very cold temperatures. Will you do it again, but encapsulate the decaying materal with polythene sheet?

Having a warm water heater powered by compost would be very cool!

Consider leaving gaps along the sides of the fleece cover with the compost as you used it here. I would also recommend using compost heated hot water to provide your bottom heat, as that would remove the source of gasses from the enclosed area with the plants. Another option might be to line one wall of the tunnel with black barrels filled with water. A Large thermal storage mass that would help keep the entire tunnel warmer. Sensitive plants could go right alongside the barrels, with fleece over on the coldest nights.

I started growing vegetables and fruits on an 11m x 7m plot this year. I had trouble with tomatoes as well but not for the same reasons. I’m lucky I don’t have to deal with frosts in 9b but the summer heat starting this month will be the big challenge.

I had seedlings exhibit the same damage on a horse manure hotbed. Is sealed the bed surface with plastic and that resolved it. Two thoughts; traditional management advocates leaving the hotbed to settle for 10days yet mine was still smelling of ammonia. A soil capping may adsorb gases. Good luck

The Victorian greenhouses had loops of pipe that went from the manure bins outside, to the inside, and were designed to move the heat around in the circulation by thermal expansion. I've seen some that had a second loop with a hand pump, and another large fancy one that had a boiler room. (It has a tiny room next to the boiler, that I was told was for a boy to sleep so that he could keep the boiler fuelled through the night.)

It might be worth it to consider using old polytunnel plastic to create a smaller greenhouse that is heated from the compost. Edible Acres has a lot of good videos on the subject.

Very interesting...

I have a concrete manure bay, made out of gravel boards and it must suck the heat generated by .y compost as it doesn't get over 50 degrees celsius. It's difficult getting enough cardboard to insulate it yet that's what I need to do.

did the same with grass clippings in the greenhouse a few weeks ago. burned leaves and flowers. they'll survive I hope.

An interesting issue you had, although happy you still had enough young shoots to keep them going. Would it be worth having the fleece raised at one end towards an exhaust vent/stovepipe design to try get a current of moving warm air towards the vent and carrying any harmful decomposition gases on its exit route? I find the simplest solutions are often the most satisfying when they sometimes work.

If you have time, check out Idaho Family Farm and Homemaking formerly Dirtpatchhaven. She does a lot of hot bed stuff and has for years. She is in the cold desert so the environment is different but she may have some tidbits that will be of use to you. I don't know that she has had the problem you are experiencing but she is a pro at this. I didn't provide a link because I don't know if that would be cool with you. Though I can and will if you would like. BTW, I'm always so happy to see a new post from you. I appreciate the knowledge and seeing your beautiful gardens.

Hi Bruce! If I could give you a tip- when transplanting make sure the tomatoes have at least 7 leaves intact! Any less and they will have trouble photosynthesising enough to keep growing efficiently!

What gauge hardware cloth did you use for the round compost piles that you showed here? Like the one for the shower. I think that would be an excellent solution for my setup here in an urban environment, it would have plenty of air access and contained to a spot really well.

Hi Bruce Wondering if you’ve had any experiments with hydroponics? I’ve tried it in Ireland and found it really accelerates the growth of heat loving plants that can be hard to grow in Ireland. I’ve grown the “Carolina Reaper” pepper for example in Ireland using hydroponics. I’ve also found that you can get bountiful basil plants from it.

Mad Scientist.

Interesting.

I would try just leaves. Like you said, grass is nitrogen heavy so it releases NH3. A leaf heavy compost with a small amount of nitrogen would burn slower and release less I think.

Interesting! As someone who hasn't yet invested in any fleeces but would like to have some on hand for some additional frost protection, do you have any tips given the benefit of hindsight? I was thinking just a 2m wide roll of 30g weight.

Why not combine the shower concept with the hotbed? Have the pipes from your shower setup run underneath the tomato plants. The only issue would be moving the water, but I suspect that using a small pump with a small solar panel and a simple power bank would suffice.

What software do you use to track your yields? A spreadsheet?

I'd consider a layer of several inches of dirt on top of the compost pile (any compost pile actually, but particularly important here). Clay adsorbs ammonia, so should help with the poisoning (not to mention capturing vital nitrogen that's been disappearing into the air)

I'm trying this atm if you want some ideas to consider? Are you having another go at it?

Have you ever grown tomatillos?

Why is it only HORSE manure you get in these beds? There's almost no horses round here but plenty of cattle bedded on straw. Would cattle dung not accomplish the same effect?

Biochar will absorb ammonia, so it's worth testing out. Might enable a fix if people only have the compost you just used available.

if I couldn't start my tomatoes indoors I don't think I'd be able to grow them at all. I just use the standard fluorescent tubes in double fixtures for my starters, seems to do the trick.

Perhaps a sheet of plastic between the compost and tomatoes could prevent gases from the compost affecting the plants

Could it have been ethylene?

To co mówisz jest interesujące

👍🏾

As part of your conclusions, your initial worry not to create too much heat probably was the first step in the wrong direction and cause of your problems. As you seem to have concluded later, it's far better to create an excess of what you need than to not have enough. And, as you might know, if you had created a real hot compost pile, the pile would have generated temperatures up to boiling water which could be repeated up to 12x until your compost pile's reactions stopped which would be roughly over a course of about 9 weeks. If frost is predicted sometime over a 9 week period, then I don't think there should be any problem timing your compost pile to provide more than enough heat to supply the poly tube of your plants. The other major problem is of course your design which was to do your hot compost directly under your plants and only about a foot tall. A proper hot compost pile is exactly 1 cubic yard (3'x3'x3') and as I described should generate much more heat than you need over those 9 weeks or so (out of a total of 12 weeks). A hot compost pile that is turned will take about a week to get started and 2 weeks to cool down at the end which is how I calculated the 9 weeks as a heat source. Because your hot compost pile needs to be turned to maintain high biological activity, ironically to generate that amount of heat you need the large pile in cube form (not spread out like what you did) to create the insulation to cause the high biological activity. So, you probably should locate the pile on one end of your poly tunnel, not under your plants. The other major design problem is as you described, contaminating the air your plants need to breathe. Take a look at the design of a common furnace to understand what you should design, which is to isolate the firebox and use a heat exchanger to transfer heat to the desired environment. In the same way your hot compost pile must operate in its own environment separate from your plants and use a heat exchanger to transfer warmth to your plants. Or, perhaps increase the air circulation so much that both your plants and the compost pile are supercharged with fresh air. So, for example don't try to heat your plants continuously but blow air and heat from the compost pile though your poly tunnel for about 15 minutes in the early evening and again once just before the earliest hours before dawn when the temperature is coldest just enough to relieve the plants when temperatures are coldest and let them have regular air the rest of the day and night. Which reminds me... Depending on the plants you're growing, I do know that farmers often turn on the sprinklers during frost so that ice forms on the plants if the temperature drops below freezing. The idea is that ice forms a protective barrier because once formed, ice cannot drop below freezing temperature and so protects the plant from any lower temperatures.

Excellent?

With the loss of the lower leaves/branches, why didn't you lay the plants on their side at planting, as not to plant to deep, the plants will stand up by themselves. I buried 5gallon buckets in my compost heat bed, as the water warmed it let off moisture, and maybe trapped the glasses, my Gramma did that in her hoop house, recall her saying she did that in the Canadian prairies to keep water from freezing for watering her chickens, she did it in the horse manure pile outside the barn, and then in the early spring put a table over it after taking some off and spreading on the snow covered straw pile base, where her potatoes would be planted. She shared these stories as we sat in the garden under a apple tree shelling peas. The homesteaders learned and did as of not they didn't eat. They immigrated to the prairies in 2905 as Grampa saw WW2 coming and clear some land and farmed, the mounds, and shape of the earthen straw cover roof house Dad was raised in is still visible, my Cousin still gardens on the very see spot, every fall some straw/hay bales are put there, covered with horse/cow compost pile manure, and in the spring it starts all over again, imagine a garden in the same spot almost a 120 years later, and still a garden neighbor talk about. Hopefully her kids do the same.

Dowding uses horsemanure, but I don't think he covers it. Though, I also think he does it with more cold tolerant plants. Do you have a video on timing your tomatoes in the polytunnel? I'm surprised how well developed they are so early! I didn't get my polytunnel up until May so I wouldn't have been able to follow your method, but I would love to have tomatoes on the way in early June next year!

I know you do a lot of Grow Bag gardening. Have you looked into "Straw Bale Gardening"? This utilizes the decomposition of the bale, and means no need to dig. I recommend reading "Straw Bale Gardens" by Joel Karsten. I used this method the first year i moved into my new house, before I got the ground cultivated. It may prove useful to you, in some cases

Battery, solar panel, heater

Need some horse or cow poop n if uve got any old newspaper not glossy magazines... layered with ur vegetable scraps

Interesting video 👍 You might find this method of warming (or cooling) interesting: kzfaq.info/get/bejne/kKqPZsKY2M3Xnp8.html. There are also various approaches involving a porous thermal mass such as glass chippings, which are typically placed in a large dug out area under a tunnel or greenhouse, although I suppose it could be adjacent, and air circulated through them. During the day, warm air (ideally drawn from the top of the tunnel or greenhouse) is pumped through the mass to warm it. At night the colder air is pumped through to warm the tunnel/greenhouse. I've never tried it but there is lots of information out there on this sort of thing - and it only needs power for the fans. I imagine you could do something similar with pipes running through a pile of fermenting compost (which would not have to be in the tunnel).

Very interesting as per usual Bruce, I built a hot bed beginning of this year with horse manure and straw, it would have been better had it been really fresh but it worked well, I will expand this idea if possible in February. Video of how we did it using pallet collars, it was quite straight forward, I covered the whole thing with a frame to drape fleece over the top at night. kzfaq.info/get/bejne/r5lgebKavbqqh4U.htmlsi=_hbaysJRbWXjVL27

First

A video from No-Till Growers details a method used by Wild Hope Farm to heat their tunnels. There's a few good parallels between the methods you came up with and their own. kzfaq.info/get/bejne/mLGYjbd1292mdqc.html

Interesting.