Tedi - KEY QUESTION: When does this experiment start and when will it be completed? That will be important to the way you go about it. So let us know so we can give you the right advice! Also, you said growing plants FROM SEEDS, right? Liriope is commonly known as monkey grass. It's the kind with the stems of purple flowers. Just go to any store with a plant section and ask for it. However, I don't know of too many places you can buy the seeds. Your neighbors might have them if their monkey grass has dropped seeds.
Mr. Hall is a great guy and he gives good advice, but he is also a high-level (rocket - yes, REALLY) scientist and he gets a little technical sometimes. LOVE YA DAVE!
So let me offer some less complicated advice so you have some options. According to my high school science teacher sister, using 5 to 10 plants for each method should do just fine at your 7th grade level. There are several plants that grow well from seeds and we can recommend different types but we first need to know how much time you have before the science fair. Radishes grow very quickly from seed, and so do pinto beans, for instance...
This advice will work no matter what you grow: Try to use a potting soil that doesn't have any fertilizer in it to start with. Read the back label of the bags in the store to see. Most potting soils have a fertilizer of some kind in them. If that's hard to do, you can just buy a potting soil with a chemical fertilizer in it like Miracle-gro and then follow the instructions using the Miracle-Gro fertilizer for your chemically grown plants. For an organic potting soil you can use a combination of things like compost, cornmeal, lava sand and green sand, or there are two or three brands available in organic stores around Denton. Schultz makes one that you can buy at Lowe's.
Put the plants in individual containers so that you can tell later how each of them did during the experiment. Measuring how tall or broad they grew, how much their roots grew, how many of the original plants are still alive at the end of the experiment and how much money you spent on each set, organic and chemical, are good things to measure. Also make sure they get the same amount of water and sun or light exposure as that makes a difference in most plants. Water them daily for the first week or so and then regularly but not too often. Few plants like to be wet all the time.
When you plant the ones on which you will use organic fertilizer, you might use liquid seaweed as a root activator and fertilizer. Generally you will want to soak the seeds in seaweed overnight before you plant them. You can buy a bottle of liquid seaweed for about $6.00. One of the fun things about organic fertilizers is that there are many kinds, and they have interesting smells and natural colors! Seaweed smells like dirt or rock. Medina Soil Activator smells like Sprite! When you spray molasses on your lawn, it smells like a sugar cookie...and stuff like that. There aren't any organic fertilizers that are blue or bright green or yellow and none of them smells like plastic.
Yes, I will be happy to give you an interview or help you find another person like Mr. Beck or Mr. Garrett (if he's not too busy), or someone else. I know many people who work in organics and will help you find the ones you want to talk with. I know a lady who raises herbs organically, and organic farmers and ranchers, so you tell me who you want to interview and I'll help you get in touch with them.
There are lots and lots of websites you can look at. Try these:
www.malcolmbeck.com - Lots of good articles but maybe a little advanced.
www.kidsregen.org - Which also has some good links to other information. It's geared toward younger kids but it's useful and helpful to a beginner.
www.organicgardening.com - Take a few minutes to look around this one.
I know it's hard to learn about this. That's why all these forums and websites exist. Mr. Garrett's books on gardening are really helpful. I'd suggest you have your dad get one for you or check at the library for them. Rodale company makes some good ones too. Do a search on some search engines for "organic gardening" - AOL gave me over 46,000 of them!
Let us know how we can help more. That should get you started.
Kathe