Hi fluffyunicorn,
Questions are great - I'm happy to help.
Unless your teacher tells you otherwise, I don't think you need to have all 18 data tables on your board. But, they should be in your lab notebook, and your lab notebook should be at your display. The purpose of your display board is to summarize your project in an easy-to-understand format. So, I find that graphs are much more helpful on display board than data tables are. For your display board I would definitely combine all of your data into one summary table.
But, ask your teacher to see what he or she wants. If your teacher says you need to have all of your data tables on your display board, then you should do that. Your teacher sets the criteria for your project, not me or you
Here's how I suggest making a summary table. By the end of three trials, you should have data on a total of 24 seeds from the upright sandwich, 24 seeds from the horizontal sandwich, and 24 seeds from the rotated sandwich. (There are four seeds per sandwich, and you had two upright, two horizontal, and two rotated sandwiches. This means each trial gives you data on eight different seeds that grew under the same conditions. Then, you repeated the experiment three times. 8 times 3 = 24, so you have data on 24 seeds upright, 24 seeds horizontal, and 24 seeds rotated). For each day, I suggest averaging the data from all 24 seeds that grew under the same conditions. The board isn't letting me attach another file to this post, so I put an example here:
https://sites.google.com/site/seedsandw ... mple-table.
As far as graphs go, I would make two sets of graphs: one for your display board and one for your lab notebook. For your display board, I would graph the averaged data from your summary data table. That is, I would average the data (for each day) for all 24 seeds that grew under the same conditions, and then plot those averages on the Y axis and time on the X axis. For your lab notebook, I would make one graph for each of the 18 data tables in your lab notebook.
Let me know if I can help with anything else!