I'd check pH before I spent time blowing leaves off a plot. Where I've got heavy oak leaf litter, and plenty of branches that have fallen, my clover grows very well. By early summer, there's no evidence of leaves. They're still there, but they're breaking down and everything has pushed up through them. I wish I could spread an inch of bur oak leaves on every inch of plot i've got. Seven years ago, I spread a hot dose of lime under those oaks, and haven't had to reapply since.