Answer: I think your lilac is responding to the stress of the hot weather and of being recently transplanted. The shrub spike shouldn't make any difference at this point. Daily watering is a bit excessive, though. While lilac's like to be watered regularly, they prefer a deep soaking once or twice a week (if the weather is really hot). The roots need oxygen as well as moisture. Watering daily can drive the oxygen out of the soil and suffocate the roots of your plant. So, water deeply and then place a 1-2" layer of mulch over the top of the soil to help slow evaporation. Wait 4-5 days and water deeply again. This will encourage the roots to go deep which will help keep them from drought stress when the weather is hot.
By next spring your lilac should leaf out and flower right on schedule.
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