Tip: season-end plant sales
If your garden needs more plants -- and whose doesn't -- you really need to take advantage of plant sales. There are typically two times of the year when the nurseries near me start reducing prices: mid-summer, and mid-fall.
Mid-summer plant shopping is not fun, as the oppressive heat and humidity makes browsing plants an uncomfortable experience, but fall sales are another thing entirely. I've been visiting local nurseries in the cool/cold weather lately looking for bargains, and I've found a few recently.