|Dahlias and zinias, something is already injoying the leaves. seeing partially eaten leaves and small holes.. what to use|
|Slugs and snails enjoy the petals of both. Look for slimy trails. Or, caterpillars can munch on them. On occasion, earwigs can do the same, especially in dahlia flowers. Without knowing for sure what the pest is, it's difficult to make a recommendation for control because not all pesticides will control all pests. Go out at night with a flashlight - if you see slugs or snails, use an iron based product such as Sluggo. Turn over the leaves and look for caterpillars. You'll usually find frass (bug poop) on the ground or on leaves just below the feeding. If you find evidence of caterpillars, Dipel or Thuricide will control them.
Best wishes with your garden.