Earthtainer Greenhouse????

[dfollett]

Earthtainer Users,

I'm new here, but want to thank you folks for your efforts and for sharing. It's been fascinating reading through these threads.

I just finished building 18 earthtainers (and 4 Inntainers) and am eager to get started. I purchased a roll of the stretch wrap (the stuff that they use to wrap pallets) and intend to wrap the cage of the earthtainer then cap it to see how much of a jump on the summer I can get.

It is still too early here to set anything alive outside, but I am going to set out some empty containers soon and monitor the temperature difference between the interior of the wrapped cage and outside temps (and the soil temps). I'll do that for the next month or so to determine when I dare set the plants out. I will try both with and without aquarium heaters in the bottom.

Has anyone had any experience attempting this? if so, is there a thread discussing it? I will pass along whatever I learn (if I learn anything). I'm using dark colored containers so the soil will warm more quickly - not worried about cooking roots, as our nights are seldom much above the mid 60s. I'd rather build on what someone else has learned if it has been tried.

Anyway, it should be interesting.

[Rockporter]

Wow, I know someone used some heated cables inside an earthtainer but I don't know about fish tank heaters. I would be concerned about the water level going to low and the heaters exploding because they got to hot.

Welcome to TV, I will be watching your planned experiments.

[JamesL]

Welcome and congratulations on a massive build!
I recall reading about the use of aquarium heaters somewhere, but I can't pinpoint it at the moment. Use of the pallet wrap - I like the concept and it should work, presuming of course you can regulate the temps.
Good luck, and I am also looking forward to reading about your results!

[Doug9345]

The only thought I'd add is that I'd make sure that I took temperatures just before the sun came up and started warming them. That will be the most critical time.

[Cole_Robbie]

Unless it's nighttime and frost is falling, you want the top of the shrink wrap to be open. Otherwise it will get too hot and the condensation inside won't dry out.

And if you heat the water in the Earthtainer, whether with the sun or an aquarium heater, I think it will rot your roots and grow pythium. Or at least that will happen very quickly as your weather warms up in the spring.

Good luck. As long as you monitor everything closely it will be fine.

[dfollett]

Thanks for the input. What temperatures are best for roots? I am going to monitor the soil temps in the containers. I don't know that I'll have much control over them. That's one thing I want to learn. I'll monitor the soil temps as I expose the container to more sun, or shade it from the sun. It should be interesting.

[dfollett]

I intend to build a removable cover that I take off during the day and put on for those nights where the forecast is for frost. I figure the soil will be a heat sink that (hopefully) will radiate enough heat into the top to hold out the extra low temps. A few degrees on those extra cold nights will buy me a month on the front of the season - no help at the end.

[Cole_Robbie]

What temperatures are best for roots?

In an Earthtainer specifically, that is a very good question. It would be fun to experiment to find out.

I do know that hot root zone temps are a death blow for hydroponics setups. The temp at which water stops being able to hold the greatest level of dissolved oxygen is quite low; I've read 57 degrees. That's coincidentally supposed to be roughly the constant temperature of sealed underground bunkers. With every degree above that, you begin an exponential curve. Over 90 degrees, water can hardly hold oxygen at all. At the same time, there is also an exponential curve upward of bad bacteria like pythium that rot roots as your temperature increases.

I'm not saying your earthtainer needs to be exactly 57 degrees, but the general idea is that roots prefer to be cool. Even on a hot day, it's nice and cool at the soil level of a big plant's deepest roots.

[dfollett]

That's good to know. I've also read, and observed here with plants doing nothing until late June, that tomatoes don't do much until the soil warms up (although 57 may be warm for soil). I started investigating tomatoes in containers after last year's experience. We always end the year with a few red and lots of green tomatoes (90 days frost-free). I planted several tomatoes in black plastic planters (the kind that trees come in) and one earthbox. They ripened significantly earlier than those in the ground. I attributed it to warmer soil in the containers.

After a lot of reading, I became sold on the earthtainer concept. I appreciate your input. I'll try and learn more about root temps. In the meantime, I first need to see how much temperatures inside the wrapped caging remain above ambient temperatures during the early morning hours. Hopefully, I won't need to cook the roots to keep the plant from freezing.

[rnewste]

For the first year, I would start your experiment wrapping just 2 EarthTainers in the wrap (after all how many tomatoes can one eat) being sure to ventilate them at the top, as another poster mentioned.

The fish tank heaters proved of limited success here in California (the heating of the sidewalls from the Sun proved equally effective). Make sure you buy ones which won't crack if they are out of water!

Raybo

[dfollett]

Thanks. I'm thinking they'll be beneficial here. Our average lows are 40 in May, 46 in June 53 in July and 51 in August according to The Weather Channel (seems a little too low to me). Much more cooling time than heating time. Our median last frost date is June 3 and median first frost is September 12 (average 97 day frost-free). I can't do anything to help on the back end, so I'm hoping to get the gains in May.

I have done some research and learned that the ideal root temperature for tomatoes is between 68 and 86 degrees (that may not apply in hydroponics as per the post above). I have also learned that an aquarium heater in an 'Inntainer' in a room that is a steady 59-63 degrees maintains a nearly constant 'soil' temperature of about 71-72 degrees. It will be interesting to see how they work with the wide fluctuations that occur outside in April and May.

[dfollett]

How do you know if they will or will not crack if they are out of water? Do you have any source for those that won't?

[amideutch]

Getting into this a little late but like the idea of the 'Stretch Wrap'. Don't have to worry about securing it as it does that automatically and is easy to remove when the temps stabilize. Solution heating is not new and has wide spread use in hydroponics, especially in NFT where they heat the nutrient solution. It has shown to greatly enhance plant growth especially in cooler weather and allowed greenhouse growers to lower their thermostats.

But with the earthtainer I would only use heating under two conditions. You use an auto top off valve as Ray does on his so as to keep the water level constant in the reservoir and use a sterile growing medium void of bacteria/fungi. Reason being you don't know what type of bacteria/fungi you have in the normal aggregate and heating it can cause the bad guys to proliferate as well as the good which can cause disease problems.

Ami

[dfollett]

Thanks. It's always that thing that you didn't think about that bites you, and I'm sure there are a hundred other things I haven't thought about (That's why I made the post). I'm sure the potting mixes aren't sterile, so that generates numerous questions: How to sterilize the soil? - How does sterile soil change fertilization requirements? - etc. etc.

However, don't you have the same potential issue with bacteria/fungi as the soil naturally heats to those same temperatures during the course of the year? Other than being warmer longer (which it is already in those areas with longer growing seasons), how is what I'm proposing adding to that risk? (as long as I don't heat the soil to levels beyond what it naturally reaches)?

[amideutch]

However, don't you have the same potential issue with bacteria/fungi as the soil naturally heats to those same temperatures during the course of the year?

If you cover soil with black plastic mulch you can have the same problem. Otherwise if you stick your finger in the soil on a hot day you don't have to go down far where the soil temperature starts to cool. In a SWC you are in a closed environment like a fish tank and any changes in that environment are magnified due to the lack of buffering do to the size of the container. Same difference if you fill up a bucket with water and set it out in the sun or dig a hole in the ground, put the bucket in the hole and fill with water.

If you use a soiless mix for your aggregate I don't think you will have any problems. And yes there are sterile growing mediums. Coir, Rockwool, and Perlite to name a few. If you inoculate your seedlings on plantout with Mycorrhiza and beneficial bacteria they will help to fight off disease and make nutrients more available to the plant. MycoGrow soluble is one such product I use and have had good results with.

Ami