Start with a membership…
We became members of the Missouri Botanical Gardens because we visit several times a year and love the place! We paid $115 for a friends and family membership which allows us to bring two other people with us when we visit– for free! It was worth the price right there– BUT MoBot participates in reciprocal agreements with over 300 gardens and we thoroughly enjoy that. See the list here: https://www.ahsgardening.org/gardening-programs/rap/find/statebystate
Closer to home, you can join Minnetrista in Muncie. Or Newfields in Indy and get reciprocal discounts or free entry to art museums AND botanical gardens!
Many gardens waive their entrance fee while others give discounts. A few have blackout areas (say, 90 miles). Check out the details before joining your favorite garden — and then take full advantage of this amazing feature on your botaniquests.