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]

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?

[dfollett]

That'd be a great name for a movie!

I'll start with the ugly: I jumped to conclusions way too soon! What happens when the temperature drops from 35 on a sunny day to 10 at night is different from when the temperature drops from 35 & cloudy to 25 at night. In the latter case, the temperature gain is as little as 2.5-3 degrees. Raybo was right.

[QUOTE=rnewste;327229] The fish tank heaters proved of limited success here in California (the heating of the sidewalls from the Sun proved equally effective). /QUOTE]

Apparently the soil does not radiate heat to the top consistently enough under different conditions.

Now, the Bad: One of the fishtank heaters has already stopped working and it can't be changed. Oh well, they were cheap ones (maybe that's why it quit working).

Finally, the Good: I've learned you can't get heat from the water to the top of the 'Tainer consistently enough to help at night - even with 100 watts going full-out. (Folks who have greenhouses or experience with cold-frames probably already know this stuff I'm just learning). That means I'll have to introduce heat directly into the top.

I'm playing with several ways of doing that, some of which look like they'll work. I think I only need 15-35 watts of heat into the top of the 'Tainer with the lid on. It appears (I'm not going to jump to conclusions too soon this time) I get about 1/2 a degree per watt. I've tried 16 watts and 22 watts. The first few days have been relatively consistent. I'm trying 32 watts tonight.

I have a couple of objectives:

• Pick a ripe tomato, grown outside in one of the Earthtainers, by my normal frost-free date - 1st week of June.
• Set up something that works automatically except for adding water, putting on the lid at night and taking it off in the morning. No wheeling them inside or covering them with blankets, etc. Nothing that takes too much effort (other than the initial setup).

If this works like I hope it will, I'm going to plant a couple before the end of March. I'm thinking of planting one with 1 Sophie's Choice (I've seen a lot of good comments) and 1 Siberian (It claims the shortest maturity) and a second with Sophie's Choice (to compare with and without the water heater) and 1 Sasha Altai. I haven't grown the Sophie's choice or Sasha Altai before. I want something that won't outgrow the top or the 'Tainer, as I will need to put the lid on for at least 2 months.

If anyone has suggestions for better varieties to plant, I'm open. The varieties I have to work with that are small and determinate are Sophie's Choice, Silvery Fir Tree, Beaverlodge Slicer, Bushsteak Hybrid, New Yorker, Siberian and New Big Dwarf.

Will post again when I know more.

[rnewste]

One of the devices I looked at to keep the above ground environment at a warmer temperature in the spring, were reptile heaters. I didn't follow through on trying them, but you may want to research them.

Raybo

[dfollett]

Thanks for the suggestions. The 16 watt heater I've bee testing is a seedling heat mat attached to a piece of Masonite and zip tied to the inside side of the cage. It seems to work well, but I think I will need a little more wattage. The reptile heat mats are similar, but with more variations on size and wattage. My 30 watt trial right now is the seedling heater and a 14 watt candle warmer in the same cage. We'll see what that does.

[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.