Personally, I wouldn’t. I’m okay with posting the same bird at different times because, well, it’s an animal. More is likely to have changed since I last photographed it. But plants… I wouldn’t post the same individual plant multiple times unless a lot had changed. Multiple observations of the same species are fine, although you should exercise good judgement - e.g. don’t just photograph every single dandelion in your yard and post them as separate observations. But others may disagree with me.
You may want to check out this topic for more opinions.