You dont want to avoid fundraising even if you think you can finance the whole project out of your checking account. Asking participants to give or raise money for a project is a time-honored way of cementing interest and loyalty and of uncovering hidden resources. These resources can be monetary, but they might also involve expertise, talent, and a shared passion for the project.
You may cringe when you hear the phrase were not fundraising were friend-raising, but its true. For an individual, a person becomes emotionally committed to whatever they support with effort or money. For a community, getting gifts from charitable organizations or businesses greatly enhances your chance of having the school garden project noticed and nurtured in the long run.