Back in the 60's I did a project showing different fertilizers on tomato plants, got a 1st place in county wide science fair. I used a commercial fertilizer, no fertilizer and ammonium nitrate from the Farmer's Co-op. You should be able to get the last one in small amounts if you tell them what you want it for or they may suggest something else if you tell them what you are doing. I used poster board to mark their height every day, photos every week and write it all down. The key is to document every thing you do and in as many different ways as you can.
1. Which grows better soil/water?
2. Which grows better light/dark?
3. Which grows better music or no music?
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Marigolds are very easy flowers to take care of. They don't need much work except to dead head the dried flowers. Just pick off the dead flower heads when they dry out and your plants will spread like crazy. The dead flower heads are the seeds. They will grow in almost any soil, in the shade or in full sun, and just need watering once a week unless it's very dry. My husband and I have grown our own Marigolds for years with seeds that we keep when we dead head the flowers every year. If you want to keep growing them, just put the dead flowers in a brown lunch bag and let them sit all winter. Then plant them after the last frost and you'll have flowers all summer long and into the fall!
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