The only reason I can't give the wildflower center a 5 star rating is the $7 admission charge. It just seems a little steep to me. Of course I go every year in the spring, so it must be worth it.
Easy access from downtown the wildflower center is just off Mopac. There isn't much parking at the wildflower center (Especially during Wildflower Days), but plenty of free parking along LaCrosse. Even when there are cars lining both sides of LaCrosse, the gardens don't seem too crowded - they seem to absorb the people well.
The wildflower center has beautifully planted formal gardens as well as natural fields of wildflowers. Well marked easy trails wind around the property. There's a tower for viewing (though not much to see - the climb is more fun), a better than average gift shop, kids crafting area, cafe and a few well marked Kodak picture spots.
I generally spend about 2 hours when the wildflowers are in their peak - generally late March to mid April.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.