Since water is unlikely to be the issue, check out the sun vs. how long the plants have been in the ground. They may not have gotten a lot of new root growth into the soil around the plants yet, and if they are in full sun, that will be stressful for most big-leaf hydrangea/H. macrophylla which prefer shelter from the hottest sun, but even more stressful for young plants. I try to plant these where they will have morning sun and afternoon shade. How much sun are these getting? What is your soil like? With number 3 with the limp stems, there is a water issue, either too much water causing root rot which interferes with water uptake or too little water. Does it perk up in the evening or by early morning when it isn't in full sun? I would stick my finger down into the rootball right next to the plant and also into the soil farther out to see if it feels soggy, moist or dry.

You can also trim off the old stems that haven't sprouted leaves by now.

You guys had a late frost somewhat recently in May so I suspect the leaf color change is due to a leaf injury from the frost. Not much to do now but see if the plant will keep or drop any/some of the affected leaves.

NHBabsI think you're right - they may be getting too much sun especially because they're "young". In April I moved them to their current location, which is east facing so it does get morning sun but even in the afternoon it's quite bright. #4 is the only one that gets some shade because it's underneath a maple tree and that one is doing the best. I really don't want to move them, but should I? The only place I can move them gets afternoon sun (morning shade). I'm not sure why the 3rd one would have a water issue - I water them pretty equally and it's the same type of soil , they're only a couple of feet away from one another. How often should I be watering them? Should I be using fertilizer? As for leaf injury from frost - possible but I only noticed the purple the last few days especially with the drastic changes in temperatures...it was kind of chilly last Monday and today it was around 30c. I'm hoping the temperatures are the reason and I can just wait it out until we get more stable temps. I appreciate the advice, thank you.

Try watering when the soil feels dry if you insert a finger to a depth of 4", about 10cm. You can do this test daily for 2-3 in the early morning hours and make notes when you have to water. Each time you water, give the shrub about the same amt of water (about 1 gallon or 3.8 litres in Spring and slightly more in the Summer). Look at the notes after 2-3 weeks and see -on average- how often you were watering (every 2/3/4/etc days). After 2-3 weeks, review the notes and set your sprinkler to deliver 1 gallon on the same frequency (every 2/3/etc days). Then if temperatures change a lot and stay there, use the finger method again for 2-3 weeks to see if you need to tweak things. You can also use a soil moisture meter. Increase the amt of water per watering in the Summer but reduce it in the Fall when temps come down. No ferts just because of this.

Cooler soil helps as well. If you can utilize any companion plants (e.g. hostas) that don't interfere with hydrangea growth, their leaves will keep the soil cooler, which is better for overall growth and keeping the soil moist.

Don't fear purple leaves though. A leaf that is not droopy or crumbling, otherwise intact is a healthy leaf.

Q

Thank you everyone - I actually notice purple (and now brown) leaves on a few other plants include my mint. I added some compost around the hydrangeas (and mums because they're looking pretty pathetic too). However, I think I know the cause - I have not been watering them enough! And we've had really hot days the last few days. The 3rd hydrangea is pretty much at its wit's end...I'm hoping I can revive it. I'll be watering all my plants every night now - I'm thinking 15mins with the sprinkler should be enough with really hot weather and every other day with a bit cooler temps? I'm completely new to gardening so I guess I'm learning trial by error lol.

I noticed as I was leaving for work this morning the 3rd hydrangea that was all wilted has perked right back up!! I thought for sure I killed it. Glad to know purple leaves are normal. I'm hoping the mums I planted will also survive - they are in much worse shape.

I planted several perennials over the last several weeks but I did not water them sufficiently - I was actually worried about over watering them as I've killed a number of plants that way but I have come to learn that I need to water new plants often especially in this heat. Thanks everyone

I realize this may be a hard question to answer but anyone know what variety of hydrangeas these are and when they bloom?

The hydrangea that was near death (with the purple leaves) is the only one that's starting to have some budding flowers (white and pink) - the other 3 have no buds. Anyone know why that would be the case?

Assuming the blooms on the others are simply not late, that's very common when late frosts zap your flower buds in the garden and sometimes leave the next plant unaffected. For some reason, plant A's flower buds get zapped and the next plant(s) beside it is fine.

At worst, I would allow 1-2 weeks of waiting since these are new plants with small root systems. If there are no blooms by then, they probably got zapped by late frosts.

Also, moving them to a new location this year may have interrupted the blooming process and the plants decided not to develop buds. Happens when the roots are disturbed.

Thank you - so if they did get zapped does that mean they will never bloom or they just won't bloom this year?

You said you moved them in April? If the blooms that got zapped belonged to the ones developed for Spring and these shrubs rebloom, you may get another flush in the Summer. If the shrubs do not rebloom then you may have to wait until Spring 2018.

One can only hope and be positive! I have an unnamed lacecap that bloomed very early this year (March) and is reblooming now; it is in the broccoli phase! It has never rebloomed before and it is about 12+ years old. Nice, schocking surprise.