Re: Can plants be grown in jello or a gelatin?

Date: Sat Feb 21 15:30:47 1998
Posted By: Eric Biddinger, Grad Student, Horticulture, Penn State University
Area of science: Botany
ID: 885435283.Bt

Message:

MadSci Network: Botany

Joey,

Wow! Great question!!!!

What we are talking about here is replacing soil with Jello. To answer this question, we need to think about what the soil provides to the plant and question if the gelatin can do the same. Plants get water, physical support, nutrients, and air from the soil. How does the gelatin affect these factors?

The gelatin appears to have plenty of water that the plant can use. Compare the box of powder to the amount of gelatin it makes. The entire difference is water. So we have enough water for plant growth.

Physical support is important in soils. How else can that huge oak tree stand up strait? But I don't think you will be growing a huge oak in gelatin (That would take a lot of Jello!!) You will probably use a small pot. Physical support is no problem because you could put a stick or rod beside the plant and tie them together to hold the plant upright. Problem solved!

Nutrients can be a bit tricky. There are 13 elements which plants need to take up from their roots. (Three other elements, oxygen, nitrogen, and carbon, come from the air, making a total of 16 essential elements.) We would have to add a mixture of fertilizer to the gelatin as we mix it up to be sure that everything the plant needs is there. Plants take up some nutrients in forms that are poisonous to you and me. So you can't eat the same Jello as the plants!!! After a while, the plant will soon use up all of the nutrients in the gelatin. So if you are growing a plant for a long time, you might need to change the gelatin once in a while.

Next, the roots need air. This is the point where I have some questions. I am not sure how much air is in Jello or the ability of the air to move into our new growing media. Are you using broken up gelatin or freshly molded? (Imagine sticking your finger in a new bowl of gelatin. See the hole and the air you have let into the Jello? Now stir up the whole bowl. See all of those air pockets in the gelatin? That is what I mean by broken up.) As you can imagine, the broken up Jello will allow more air around the roots. Let's assume we are using broken up gelatin. That should work.

Well, gelatin has met all of the requirements to grow a plant. But why doesn't anyone use it?

It turns out there are a couple of problems. First, what happens when gelatin gets hot? That's right, it melts! And considering most plants like warmer temperatures, we might have some trouble keeping the gelatin solid. Also, what happens when gelatin sits around for a while?

The gelatin has lots of sugar and water in it. This means that the conditions are favorable for more than just plant growth. Molds and fungi also like these conditions. If you leave the gelatin out in the open you will get lots of nasty stuff growing!!! This problem can be taken care of by sterilizing the gelatin and the plant before placing them in a clean, sealed container. This really limits the size of the plant we are growing and causes all types of new problems.

We sometimes use another substance which has properties similar to gelatin. Agar is made up of starch instead of pectin and does not melt at higher temperatures. This makes it an ideal media to use for tissue culture. (See the link below for more information on tissue culture.) Agar also has the same trouble with molds and fungi as the gelatin does. We have to use sterile techniques to keep these organisms away from the media and the plants.

I have a couple of links for you. The first is more information about tissue culture from Te xas A&M University. The second is a hydroponics sight. Why hydroponics you ask? Well, that is what we call growing plants without soil. While gelatin is not a common replacement for soil, all of the same ideas and concepts would apply.

Well, that about does it. If you have any more questions about this, please e-mail me! Keep asking those great questions!
Eric J. Biddinger
Grad Student - Department of Horticulture
Penn State University
ejb190@psu.edu

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