How to Build a Cardboard Greenhouse for $2 or Less

Click on Diagram to EnlargeThis little Greenhouse is meant to be carried outside in the sunlight of nice weather and later in the evening to be brought inside for the night. If it is kept in a cool garage, basement, be sure the temperature never gets close to freezing. I have seen tomato seedlings withstand temperatures as low as 33 degrees Fahrenheit but they definitely weren't happy! This is where the hot water bottles come in. Also you should keep the box snuggled under a cover of closely wrapped blankets on very cold nights. There will be days when the sunlight is poor. Keep them under wraps inside. A few days without sun once in a while will not effect them to much. On very cold days, but bright sunlight, you will need the hot water bottles to supplement the solar heat from the sun. Also, on good days with bright sun, no wind and near freezing air temperatures outside

I have seen little plants actually burn up in the solar heat. This is where the venting comes in and everything should be carefully monitored throughout the length of the sunlight. As soon as the box falls into the shadows and out of the warming sun, bring it inside for the night. The box temperatures will fall very quickly although the water bottles will have collected some of the heat and will slow the process a bit. You will learn a lot about going solar and greenhouse growing

with this Cardboard Greenhouse. You will also have a lot of fun showing it working to your amazed fellow gardeners. A little labor intensive. True. But it comes at a very low price.

Have Fun!

Bob

GrandBob

You may contact me at: mailto:RobertLee97@Cox.net

Tomato Seedlings 2: Will Alcohol Slow Tomato Growth?

The tomato seedlings have been steadily growing in the Mini-Greenhouse for 10 days now. Half of the 150 beginning plants have been watered with a solution of 95 parts water and 5 parts Alcohol ( 90 proof Gin). I heard that rubbing alcohol (denatured alcohol) might work but since it will make people and pets deathly ill, I thought better of it. I picked half the plants at random to be fed the alcohol solution and half to be given tap water. Tomorrow will be the 7th day since I started this test to see if Alcohol could slow down the growth of baby tomatoes. If you've read the first article "Tomato Seedlings", you might remember that I had about 250 "Pink" tomato seeds that I was in the process of saving, sprout in the fermentation water. I had forgotten them! Should I throw them out? Could I throw them out? They were 2 months to early for This Zone. Or, I could use them to test out my experimental Mini-Greenhouse that is in its second winter of testing. I needed seedlings to do that and this couldn't have happened at a more opportune time.

And I can kill several stones at one time. Test the Greenhouse. Test the growth slowing properties of alcohol on tomato seedlings, and if they survive; perhaps have a bunch of tomato plants to plunk in my garden come springtime! And you can watch me succeed with this little experiment, or watch me fall on my kyster. [What language is that word anyway??]

Mainly, with this "growing machine", I can start seedlings - outside - in a semi-protected environment. A garage, non-heated shed, or barn. At little cost. Later the plants can be trans-
fered to a cold-bed in early spring when they start outgrowing the Mini-Greenhouse. At the present time, I am using 4 regular 60 watt bulbs for growing lights, and 4 - 60 watt bulbs for heat. I could replace this with a small electric heater but we shall see. Or increase the bulb wattage. Or, if the electricity goes out and I can still heat water, the heat chamber is made to accommodate several milk jugs, 2 liter bottles etc. containing hot water.

[Last winter I tested this out in an non-heated garage, in a cardboard box with baby tomatoes inside. The box was given extra insulation with a couple bath towels draped over. The sloped front has a simple clear plastic covering to allow sunlight to enter when it's set outside. The box retained enough heat (40 degrees) from the hot water bottles to keep the small plants alive for at least 1o hours or over night. Then a new set of 6 water bottles replaced the cooled ones. I carried the box out to the picnic table on sunny days so the baby tomatoes could catch some rays. Sometimes it was less than 30 degrees outside. That's part of that story. The rest may come later if there is enough interest. "A Cardboard Greenhouse" - anyone can build -for nothing.]

Back to the Mini-Greenhouse Experiment. At this point the heat lights are on a timer but I am working on a thermostat control. I hope to write about the results as the winter wears on here in zone 7. [see new /Arbor Day Hardiness Map upgraded for your zone]. The present temperature is 36 degrees at 10:22PM. with a predicted low of 21 degrees - Wind chill 11 degrees -Fahrenheit.
Below is a picture of the little tomatoes as of today:

The tomato plants on the right half of the picture were watered with plain tap water 7 days ago.

The tomato plants on the left half of the picture were watered with 5% alcohol mix. These also have Red toothpicks inserted to identify them. The regular watered plants have blue toothpicks.

Can you see the difference? In about a week, if they grow and prosper, I will make a statistical analyses of the average height on the left as opposed to the average height on the right. I love experimenting with plants. If you do too, you might suggest some experiments we could try together and prepare notes.

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GRANDBOB

E-Mail me at: RobertLee97@GMail.Com