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Sunday, June 5, 2011

More Temperature Stats

Lettuce, green onions, basil, green beans, cilantro, tomatoes, and radishes are growing nicely in pots my Juwel 1000 cold frame. It is just sitting on the pavement in front of my house. Here are the latest statistics from my thermochons.

Temperature in degrees Fahrenheit 

At this point I've had to move the lettuce out to the greenhouse because it was getting to tall. I would still be ok, if the top of the pots was the same level as the bottom of the cold frame. I installed an automated opener  since I shared the last set of numbers.

What next. I would like to build a small box that this can sit on top of so that the top of the containers will be at the bottom of the cold frame or just below it. This would also allow me to hold in more thermal mass to help stabilize the temperatures. Once that gets setup I'll consider adding a grow light and an warming light as a heat source to get things started earlier next spring. Until then I'll be enjoying my fresh tender lettuce and green onions.

Sunday, April 24, 2011

Juwel 1000 Cold Frame: Temperature Testing Research Part 2

After looking at the previous results (see part 1) of my temperature experiment with my Juwel 1000 I decided to add a row of bottles of water around the perimeter of the inside of the cold frame to see what effect that would have.

Click to enlarge
Here are the statistics from the data for the graph above.
Maximum temperatures: 85.1F (inside), 63.5F (outside), and 23.4F (difference)
Minimum temperatures: 37.4F (inside), 27.5F( outside), and 3.6F (difference)

The thermal capacity of the water bottles was enough to keep the temperature inside of the cold frame above freezing when the weather is clear during the day and the temperature drops below freezing at night.

Greenhouse Temperature Comparison Results

After experimenting with my cold frame recently (see Juwel 1000 Cold Frame: Temperature Testing Research Part 1) I decided to do a little research about the temperatures in a greenhouse. Here are the results. All three days were clear skies and calm. The maximum inside temperature was 98.6F and the maximum difference in temperature between the inside and outside was 37.8F while the minimum temperature difference was 6.3F
Click to open interactive graph
The greenhouse is a south facing lean to style with a concrete floor. Currently there is a lot of miscellaneous stuff in the greenhouse, but nothing with very much thermal mass.

The design and size of the greenhouse seem to be able to absorb a lot of thermal energy but there is not enough mass to retain it over the night.

Tuesday, May 11, 2010

Thrifty Hydroponics

After analyzing last years results of my AeroGarden and the fact that the air pump went out on it shortly after the first year. I've quickly realized that yes the herbs are fresh, fun, and good to eat but not economical. While pondering different hydroponic options that I could experiment with for this next year I stumbled upon the fact that the AeroGarden seed holders will fit perfectly inside the mouth of a Welch's® grape juice container. A hole saw can also be used to make 2" and 3" netpots work as well.

Here is a list of materials for my next experiment.

  • Welch's® Grape Juice bottle or similar container.
  • Aquarium air pump.
  • 3' feet of air hose.
  • Silicon
  • Seed holder
    • Net pot 1.5" or 2" with clay 
    • Used AeroGarden® containers w/rockwool)
  • Seeds
  • Paint (I used black spray paint)

Aluminum foil - to prevent light from reaching the nutrient solution.

Drill a hole the size of the air hose in the top near the mouth of the container and near the bottom preferably on a flat side.

Cut a length of hose just longer than the container is tall. This piece will extend from the bottom of the container up to the top to serve as a water level indicator and a way to drain it when the water needs changed.

Use a hole saw to create a larger opening in the top of the container. I found that the easiest way to do this was to place the cap on the container and use it to help keep the hole saw centered. Be careful to go slow so that the container doesn't tear or melt. When the holesaw starts to bind put drill in reverse.

Wednesday, March 24, 2010

Juwel 1000 Cold Frame: Temperature Testing Research Part 1

A while back I was given a Juwel 1000 and this spring I finally got around to testing it out. The current temperatures over the last couple of days have ranged from about 20F to 55F.

To start with I've placed the Juwel 1000 on my back porch. It is a wood deck type porch that is currently surrounded by snow and has ventilation through the floor. With this setup the cold frame is not sealed on the bottom. Over the last couple of days I placed one of my Thermachron sensors inside and one outside and created the temperature graph above. The maximum temperature difference was 21.6F and the minimum was 0F. The maximum temperature inside was 83.3 and the maximum outside was 63.5. Minimum inside and outside temperatures were 23 and 21.2 respectively.

I have plans to put it on top of a simple plywood box that will house some containers or hydroponic systems, some water containers as a heat sink/stabilizer, and a light bulb or a small heater hooked up to a thermostat. I'll post the info when I get it set up.

Wednesday, April 15, 2009

AeroGarden Update #2

Wow I guess it has been a while since I've posted anything here. We'll things have still been growing. We have harvested over 400 grams of herb's from our AeroGarden. We also added some chive seeds to the chive seed holder since they didn't sprout. I think they must have gotten knocked out or something.

We ran out of the AeroGarden nutrients after we had collected about 300 grams. I think we probably would have gotten a lot more except for the fact that this has been grown in Alaska in the winter. If this would have been grown in the window during the Alaskan summer I'm sure it would be a hole different story.

I went down to the local hydroponics store and picked up some hydroponics nutrients and a ph/ec/tds/temp meter to help see if we could extend the season. The dill has gotten to tall for the planter and has fallen all over and is starting to go to seed but everything else is growing very nicely.

Since we have started adding the liquid nutrient I've noticed that the mint leaves are significantly larger. I don't know if this is due to the nutrient or the change in ph though. Since we got the meter we've been able to pay more attention to these levels.

Below are the results of what we have harvested and other interesting pieces of information.

Conclusions thus far:
  • With the provided tablets the savings from using an AeroGarden are questionable. By supplementing with nutrients from your local hydroponics store the economics becomes quite reasonable.
  • Maintenance has been very easy. The biggest problem I have is that the unit is in my classroom at school and not at my house. Because we are measuring everything that we harvest from it, I've missed a few good opportunities to enhance the flavor of my sandwiches. Also some of the herbs that have been taken home have gone bad because I didn't use them up quickly enough. If I had the AeroGarden at home I don't believe that I would have had this problem, that this is a personal problem not a problem with the AeroGarden itself.

Tuesday, December 16, 2008

Aero Garden Update #1

The Aerogarden has been doing well so far. Here are the current totals of what we have harvested.
  • 7.99 g Basil
  • 0.91 g Mint
  • 0.81 g Thyme
  • 0.44 g Oregano
  • 3.80 g Dill
Totaling 13.95 g

We've used over 10.21 KWH of electricity. This is measured using a KillaWatt meter purchased from

The basil really grew fast and we've actually had to prune it back three times now in order to let everything else catch up to it. At this point the basil and dill seem to be doing the best. The mint has really started to take grow now. Looking under the hood it has a pretty significant root system. The oregano is probably the slowest growing of the bunch. Maybe everything will start growing better now that it has all been pruned back a little bit.

One improvement that I would really like to make to the system is to put a little fan somewhere to help them grow stronger. I think that this would also help some of the lower vegetation to get some more light and promote stronger healthier plants.