Lack of blooms is most often from too little sun or a plant stressed from lack of water but in your case I cannot tell any difference in sun exposure and I assume they get the same water. The next most common cause of poor bloom would be root damage most likely from underground rodents feeding on roots. Do you have moles or voles? The good news is the plants should regrow roots and the problem may take care of itself with full bloom next year. Keep growing, Marianne Binetti