Ideas to warm the soil for high altitude? (Thought I saw post about using a tarp)

I live at 8000’ and we get snow into May. Nobody plants anything until mid to late May.  Everything grows VERY slowly until July. Only starting in July do my annuals start to take off. Therefore my growing season is very short. (I am trying to find my perennials for my food forest. Comfrey is establishing well but we also don’t get much water.)

I could have sworn I read somewhere here that someone used black tarp to specifically warm the soil and not for purposes of killing weeds.  EDIT: I'm now remembering I think it had to do with warming the soil with maybe a clear tarp to get things to sprout early and then let them die when you remove the tarp?

Of course hoop houses would be ideal, but I’ve yet to build one. I’m still looking for a suitable location. It needs to be sturdy to hold up to 60+ mph winds we sometimes get.

Has anyone seen the thread about warming soil with a tarp?  Does anyone have other ideas?  Thanks

Edit:  I should address raised beds because that obviously a solution.  I would like to add raised beds and am still looking for a suitable location.  I have been thinking about starting a new post regarding this because I'm curious if the materials used could be used to help warm the soil.  For instance, something like rock on the South side but a material more insulating on the north side (like wood logs, aircrete inside frames, or timber construction perhaps with additional insulation).

I wish I knew the answer to you question.

I saw this in the zero replies so I thought I would offer some thoughts.

To me the tarp idea would just hold in the cold.

What about glass?  I have heard folks using cold frames made of wood and glass?

Maybe rocks on top of your garden might help warm the soil.

Lots of bottles of hot water.

I think I may have heard about using mirrors.

If you find out the answer please share with the forum.

Growing short season crops that have been bred for a short season will be important for you so select for quickness to maturity.

If you have drier soil this will warm up more quickly then wet soil; Dark soil more quickly than pale soil. If you have warm days and cool nights then ways of protecting at night (removable covers) or retaining the day's heat with thermal mass (stones/water) will help. You can do a lot with windbreaks, stone berms and earth banks to create microclimates.

I love my polytunnel (hoop house). It is approx 8ft tall 14ft wide and we get 80-90mph winds most winters. Therefore don't write them off as a possible season extender. (I love my indoor gardening!) Stronger frames and crossbars will make them stiffer. The covers don't last forever and I've been disappointed with the latest one which i'm going to have to recover this year, so the 'sustainable' aspect of them is dubious. I'm thinking about a smaller dug-out greenhouse instead for the future...

Thank you Anne and Nancy!  I have never done this before, so could be wrong and appreciate any feedback regarding these idea.

I've been thinking about this since I posted.  I think a greenhouse of some sort is definitely in order, maybe more square than rectangle to cover a larger area for warming the soil.  And then possibly clear poly on the ground a few weeks before planting as well.  I don't think that would kill the earth under it, and after planting I may replace it with black landscape fabric.  I hate using these materials but think it's the best shot I got to really get things going, and I can always reuse them.  

For the greenhouse I'm trying to consider a few things.  Reading more about raised beds has me worried about them drying out too quickly.  We get very little rain, I am on a well, and with droughts I want to be respectful of the aquifer.  I do have many IBC totes collecting whatever rain does fall on my roof.

I'm thinking of using clear panel roofing instead of poly for the tunnel/greenhouse.  I may double up on the North side.  Unfortunately my yard slopes steeply to the north otherwise a Walipini would be perfect.  But since I'd love to grow on my north facing terraces, I may consider extending the back of my greenhouse down onto the next terrace.  My hope is the lower side can act as a cold sink to help further warm the south & higher side.  I can then plant squash or something low that could get established early (as opposed to not being in a greenhouse) because ultimately I'll need to remove some panels at the very least towards the end of June.  That will free up plenty of space for whatever I plant there.  I still might need shade cloth along with ventilation for june, it can be pretty unbearable at the height of the day killing any seedlings even though the soil will mostly be in the 40's at night.

I wish I could build an expensive larger greenhouse with a climate battery.  I've visited Jerome's Phoenix greenhouse at CRMPI and that's the way to do it right out here.  I also like the "greenhouse in the snow" concept Ross Finch did in Nebraska -- the different approach being instead of storing the heat collected in the greenhouse using drain pipe directly under it, you have tons of underground drain pipe outside the greenhouse deep enough to act like geothermal.  I just can't risk the cost without more info.  I wish I knew of success using evacuated tubes in some way to heat a greenhouse.  But I could also use compost piles.  I just have to make sure it won't attract bears.  

Black tarps do indeed warm the soil, so will clear. Though how much either will of course depends on how much sun you get at the right time.  I use black plastic to successfully grow warm climate veg like winter squash or melons without it they don't reach maturity, that plastic stays on all through the season.

You could look at getting frost netting as well, it brings early potatoes up to maturity 4 weeks early, a couple of weeks after last frost. I'm sure it could be used on other crops. Raised beds don't need to be high, just hilling the soil up a couple of inches used to give me a week earlier planting. Yes glass cloches are the traditional way to do it, and if you are rich and have a lot of time on your hands they will work well, you put them in place at least a week before planting.

Nancy mentioned microclimates of which I know nothing due to my climate being warm.

Here is a book that might offer you and others wanting to learn about microclimates:

https://permies.com/t/138107/Permaculture-Ideal-Microclimate-Aleksandar-Stevanovic

And these threads offer some interesting ways to create microclimates:

https://permies.com/t/15060/Maintaining-microclimate-stays

https://permies.com/t/33904/Gallons-Microclimate

https://permies.com/t/103202/Brush-pile-tree-hastened-blooming

I'm higher and drier than you, but I'm not sure who's colder. My garden gets last frost in early May, and first frost in late Sept or early Oct, with a cool summer.

As my soil improves year by year as I add manure and mulch, the plants grow faster and produce more each year. The first year I had bean plants that were 4 inches tall. They still produced beans!! Like, two each, and they were dragging in the dirt and looked sickly. Three years later the garden was producing much, much better, after adding cow manure to each bed once, mulching with anything I could find all summer every summer, and burying a layer of wood shavings under some beds.

I have been trying black plastic mulch, as advised by the local govt Agricultural Department. Last year I put the black plastic mulch on 4 beds and not on all the rest. I had tomatoes, squash, and melons both with and without the plastic mulch. And honestly I didn't see any discernible difference. Most of the beds without plastic mulch were mulched with broken tiles and then natural mulch as and when I acquired it.

For me, the biggest difference seems to come from starting the plants indoors ahead of time. It is often said you should only direct seed cucurbits because they don't transplant well, but I've been starting them in 1-liter tetrapaks in early April and then transplanting them out carefully in early to mid May, with 100% success. I guess transplanting is not feasible for large acreage, but for my home garden it works great. Last summer I got like 5 to 8 times the weight of winter squash off the transplanted plants as compared to the direct seeded ones. The huge producers had natural mulch, not plastic mulch, though the previous year I'd transplanted winter squash into black plastic mulch and got huge production, too.

If the weather seems dicey after I put them out, I go out and cover them in the evening with glass baking pans, clear buckets, glass jars, and even just any random container.

I'm not sure if the microclimate links talk about these, but I thought I would through out a cold frame and a hot frame as possibilities.

A cold frame (aka mini greenhouse) can be as simple as some bales of straw with an old window or door on top. Or it can be as complicated as insulated sides with a glass top at a specific angle and auto openers with soil heaters.

A low tech way people used to get warmer soil sooner was by using a hot frame. You can look it up, because I may have some of my measurements off, but the general idea was to take a cold frame and dig out about a foot of soil. On the bottom add about 9 inches of fresh manure. Cover it with 4-5 inches of soil. As the manure breaks down it produces heat and people were able to get heat loving seedlings started much sooner with this method. It means you need a source of fresh manure and would probably take some experimenting to get it right. It would be easier to build something small like that than it would be to build a full sized greenhouse. At the same time, you seem to be leaning towards a greenhouse and that would be a great solution as well.

I have not tried plastic, but I have read that the clear plastic works better than black plastic because black plastic heats the plastic and then the soil, whereas the clear plastic heats the soil and the clear plastic just helps to keep the heat trapped. No personal experience so take it with a grain of salt. I imagine either one would help.

Anne Miller wrote:Nancy mentioned microclimates of which I know nothing due to my climate being warm.

I'll just point out that microclimates can be cooler as well as warmer than normal for your area: The herb spiral is the classic example. A single large rock will give you a sunny side and a shady side. It will condense and retain moisture underneath and absorb heat through the day to increase the night time temperature. We usually talk about making our climate warmer, but cool and damp suits some plants better too.

I am with Nancy on the high tunnel/hoop house approach.   Raised beds inside the structure with ample compost on the bottom should help.  Be careful not to burn the plants. Also consider heat sinks such as containers holding water.   If you do go with this approach, be sure to closely monitor the moisture in the soil.

Nancy said, "A single large rock will give you a sunny side and a shady side. It will condense and retain moisture underneath and absorb heat through the day to increase the night time temperature.

Thanks, Nancy

That helps me understand how microclimates work.  I am really just learning as it seems to be a new word to me from last year.

I fully understand about using rocks and have recommended them to people for moisture and shade.

I hope more people will start talking about microclimates as I would happily learn more.

I remember there was a desire for a lemon tree at the Wheaton Lab or Base Camp. I didn't remember that they were talking about using microclimates though, in reality, they were.

I've seen a system in Colorado at 8600 feet where they dug up the soil under an existing hoop greenhouse and buried tubing maybe a foot underground. The tubing connected to an exterior solar collection panel.
So essentially a solar water heater convection loop that delivered the heat to the ground to extend their growing season. Not sure if this used a pump or not.

Matt Todd wrote:I've seen a system in Colorado at 8600 feet where they dug up the soil under an existing hoop greenhouse and buried tubing maybe a foot underground. The tubing connected to an exterior solar collection panel.
So essentially a solar water heater convection loop that delivered the heat to the ground to extend their growing season. Not sure if this used a pump or not.

That sounds like a neat heat system. I think that it most likely to have required a pump. It is possible that it just thermosyphoned around, but that would have required quite a steep south facing slope with the solar panel being below the ground level of the tunnel. Most likely they had a solar powered pump that would operate when the panel got sunshine.

Hi everyone.  So many great replies!   In the past I thought about using something like Glass Cloches but I think I realized the temp swings can be so dramatic that although they would help protect from  a 40 degree night, the sun here in Colorado is so intense I imagine I could easily roast my plants the next day if I didn't realize it would be a clear and warm day.  So, yes, the sun here definitely has potential to warm the soil.  I think the clear tarps make the most sense because the sun will hit the soil.  

Matt Todd wrote:I've seen a system in Colorado at 8600 feet where they dug up the soil under an existing hoop greenhouse and buried tubing maybe a foot underground. The tubing connected to an exterior solar collection panel.
So essentially a solar water heater convection loop that delivered the heat to the ground to extend their growing season. Not sure if this used a pump or not.

I was worried the danger of freezing would be too great.  I'd want to use water instead of something that may stay liquid in colder temperatures.  I love the idea of using evacuated tubes because they seem so good as producing hot water.  I could potentially put a 55-gallon barrel inside and heat that with the tubes so hopefully keep it from freezing.  Or I can use the barrel to be the main reservoir to push the water through pex underground.  But I also don't want to over-engineer this.

I garden in Loveland along the front range, so I'm only at 5,000 ft. But I'm planning on designing a cold frame for winter after hearing a podcast of a guy in Austria / Germany. Winter Vegetable Gardening with Wolfgang Palme on the Food Garden Life podcast. I also have Niki Jabbour's Year-Round Vegetable Gardener book. Basically I came to the conclusion that if they can push the boundaries for spring and fall gardening so far to include winter where they live, then I certainly can do it here. A few thousand feet might make it harder, but I think you could at least extend your season to be the same as the front range if nothing else.

The one thing we have going here in Colorado which is both good and difficult is the thin atmosphere and bright light. Sometimes the extra UV burns plants that are not adapted, which is why regional bred varieties or those that are tested for our climate are critical. No standard big box store seeds for me I'm afraid. Our dry moisture wicking winds (mostly in the winter) are also fairly detrimental to many trees and shrubs. I've heard white latex paint can help for trees.

For the cold frame i personally think it is critical to maximize efficiency for solar collection. That means getting the correct angle of the clear top. For here in Colorado that is about a 30 degree angle from the ground and makes for a pretty steep angled cold frame. I've honesty never seen one online that steep, but I'm planning on designing one and building one soon. Mine will be able to be placed on top of a raised bed i think. I am also planning on using one of those automatic vent devices. You are right, our temp swings are extreme and a cold frame would heat up rapidly and will need to be vented. Wolfgang in his podcast interview says that the most critical thing to winter growing is preventing moisture and having good air circulation. Apparently more crops can handle the bitter cold than you would think, but not excess moisture when it freezes.

I'm planning on breeding a new variety of cold frame pea. I have many really nice edible peas that are quite tasty and I hope to breed one with Lynx an extra cold hardy winter pea, and tom thumb and extra dwarf pea for really short stature.

Hi, Andrew.  Thanks for sharing.  Please post pics of your build and what you learned.  I think I've decided on a more simple hoop house to start but I really want to build something in the future.

Clear tarps at day to gather heat, blankets over them at night to hold the heat, Water bottle, wall of water or other tricks to add mass to hold the heat under the tarp.  Fruit walls is another possible.  On up to high tunnels. and up again to green houses.  A well built greenhouse can be completely self heating.

I'm only at 3000 ft and in the tropics at that, but lately, I've become obsessed with walipinis the Andean sunken greenhouses, they are not necessarily sunken greenhouses the way northerners think of them, but man-made microclimates for extreme places. Some have no roof, they are just sunken about 50-100 CMs with about an equal raised wall so that plants are protected from wind and frost.  They also control the amount of sunlight received each day, as sunlight at higher elevations is more intense. Some have permanent roofs and some have temporary roofs for when frost is suspected. The walls and/or roof can also help keep humidity in extremely dry conditions.  Its kind of like Paul's passive greenhouse--but you adapt it to where you live.  For example, I'm never in danger of more than a few degrees below freezing, but I do have cool mornings year-round, and dry windy conditions for a chunk of the year, so I'm planning a walipini--probably with no roof, where I can grow pineapple as it just needs to be a bit warmer and protected from drying out.