Answer: Based on your descriptions I am not sure what happened. Both of these plants are usually problem free with the exception that Japanese beetles will crunch on potentilla, so I am a bit surprised. To hazard a guess, however, I would wonder about your soil preparation and watering. The lady's mantle will turn crispy in a sunny location if it does not have enough water. Potentilla is more tolerant of a dry location but will also dry out and die back if water stressed. Newly planted plants are most susceptible to this type of stress. The plants should come back next year unless they were killed outright. You can always remove truly dead plant parts; if there is still life in the branches you might leave them until the normal tidying up time next spring. You might want to be sure you are adding plenty of organic matter to the soil when you prepare the planting beds, keep the plants well mulched, and then water often enough to keep the soil moist yet not soggy. Good luck with your plants!
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