Answer: There are many reasons why Hydrangeas may fail to bloom. If the plant is in too much shade, it won't bloom. Sun all morning or very bright dappled light all day should be sufficient.
And, hydrangeas take a year or two after planting to settle in and become fully rooted and established. Until then they will not bloom their best.
This has been a difficult growing season, especially for relatively new plants that are still trying to become rooted and established. Spring was cold and damp, summer was dry. So lack of bloom may be partly attributed to newness, and partly to weather and partly to overall conditions/care.
Correct watering is critical in establishing and getting good performance from hydrangeas. The soil should be organic and humusy so it holds moisture but is also well drained. It should be damp like a wrung out sponge, not sopping wet and never dried out. To know if you need to water, dig into the soil with your finger. If it is still damp, do not water yet. When you do water, apply it slowly and thoroughly to the roots so it soaks down to the deepest roots. After watering, wait a few hours and then dig down to see how far the water went; sometimes it is surprising. You need to check the soil moisture any time the ground is not frozen -- if fall is dry then you may still need to water.
Using an organic mulch several inches thick in a flat layer over the root area helps keep the soil cool and moist. It also helps feed the soil gradually as it breaks down over time. These should be mulched year round.
You may want to run some basic soil tests to check the fertility levels and fertilize based on the test results. But as a general guide, you could topdress with a good quality compost and also apply a granular or slow release fertilizer such as 10-10-10 each spring. Read and follow the label directions.
In order to have maximum bloom, hydrangeas must have enough sunlight along with evenly moist, rich soil. If the plant is not growing vigorously due to lack of light, moisture or nutrients, then it will not have the strength to form flower buds and bloom heavily.
If winter damaged the stems from the previous year (and/or you pruned them off) then that would delay blooming on the Endless Summer and prevent it on the Pink Elf.
The Pink Elf hydrangea blooms only on old wood that grew the year before. If winter killed back the stems or you pruned them off in fall or spring, then that would limit flowering. Also, spring frosts can damage the flower buds if they have begun to swell already.
The Endless Summer hydrangea is special in that it is able to bloom on both old and new wood. This means it blooms early on from wood that grew the year before, then blooms into the fall on the current year's growth. Again, pruning would limit flowering.
With these plants your only pruning should be to remove truly dead stems in late spring (due to winter damage) and after several years you may need to thin out a few of the oldest branches to allow air and light to penetrate into the plant.
I hope this helps you trouble shoot.
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