Growing things C&C please

[firelight]

Hi all, I have never gotten gotten seriously into digital photography until now. In the past I shot with film slr's a lot, but I purchased my first dslr about a week ago, and it showed up a few days ago. It's a been a while since I've tried taking nice photos, and these are the results from the first day or two. I figured the best way to get better is to open up for some criticism, so please share any thoughts.

Nikon d80
18-55mm ed lens
manual mode
ISO equiv 200

45mm f5.3 1/1600sec

31mm f4.5 1/2000sec

55mm f5.6 1/2000sec

55mm f5.6 1/1250sec

Thanks!