I presently have five Buddleja's in my garden: two 'Flower Power' near the vegetable patch, two 'Royal Purple' on the other side of the garden and a 'Wisteria Lane' near the house.

The 'Wisteria Lane' was planted this Spring, is doing fine and is not a problem (for now).
The 'Flower Power' are two the oldest Buddlejas. This year the flower spires on both are much smaller than in past years and to make things worse, one of the two always has droopy leaves the instant temperatures go over 80°F. I pruned both plants hard this past Winter and I fear this may be the cause for the flowering issues. This however doesn't explain the droopy foliage as the two are planted 4' apart (with a Spanish broom in the middle) and get exactly the same light, wind, rain etc. I have taken to providing extra water to both despite being established plants but this is not having any effect: one plant has droopy foliage, the other doesn't.
The 'Royal Purple' are exactly the same thing: one gets droopy the instant temperatures get over 80°F, the other doesn't. Here things are even weirder because the one doing better (doing great in fact: its flower spires this year are enormous) is in an awful position and I have tried watering it far less often (still not fully established) as an experiment. I havent hard pruned either plant yet.

Buddleja's here do great: you see them growing wild in empty lots and the like and there's even a truly gigantic one growing next to an abandoned factory where it hasn't been watered nor cared for in many years. All mine did great until last year as well.
I honestly have no clue what is happening: eelworms cause aborted flowers and deformed shoots, not droopy foliage, and they aren't a problem here anyway. I haven't found anything in the literature that can help so I though somebody here may have run into the same issue.

Thanks.

How long were the Flower Power and Royal Purple in the ground?

LorettaNJ said:How long were the Flower Power and Royal Purple in the ground?

The former are 5 year plants and the latter 4 year plants. The former I bought bareroot and the latter potted.
The only problems in the past have been with Oleander aphids in the Late Summer and the occasional defoliating caterpillar.

Have you checked for spidermites at the stems? Mine tend to get that here. Could be leafhoppers too.
Do you get oleander aphids on your buddleias? My buddleias is surrounded by milkweed infected with oleander aphids and so far, they stay off other plants.
That is quite a while in the ground already so you would expect them to be drought tolerant already, right? The first thing I can suggest is to water a larger circle around the plants. The reason is I have transplanted a couple of buddleias over the years and they have can shallow roots that run along the ground beyond the drip line. Maybe yours is the same.
I have had mixed luck with buddleia. I've bought several over the years, but some never become much. They don't make the first winter or I have removed most of them due to small flowers and awkwardness. However, I have a couple, including Wysteria Lane, that do well. Wysteria Lane has been in a frost free pot above ground since I got it. That is one that I cut way back when any danger of frost is over to get the weeping form but notice it isn't a favorite for pollinators. How about you? Right now, I bought one that is droopy every afternoon so far - Grand Cascade. Yet Blue Pugster does not droop. It is also came in a larger pot.

Thank you so much for your kind reply.

I have a few oleanders (planted by the previous owner; I absolutely detest them) and they are always covered in aphids this time of the year. They are very easy to spot as they are bright orange and the Buddlejas are the only other plants to get them.
No problems with spider mites here luckily, unlike my old place.

Wisteria Lane went into the ground this Spring and seems to be doing great. I haven't watered it in over a week (it rained on Sunday) and has some straw mulching and is absolutely fine. It does attract butterflies but no bumblebees. I don't know if it because a very young plant but it doesn't look anywhere like the pictures on the Internet.

I'll give some consideration to pulling out the worst affected plants and replacing them next Spring: have you got any experience with Black Knight and Camberwell Beauty?

Thanks again.

Do you have issues with Root Knot Nematodes in your area? They really like Buddleja.

I assumed eelworms were another name for nematodes?
I did try Black Knight but mine was lanky and the flowers were small. I pulled that one out but I have seen beautiful examples of it. It always looks good at the nursery. I would try it again someday. Yesterday, I came across Evil Ways. The flowers are close to the same color as Black Knight with a touch of red, but the foliage is chartreuse. I might have to go back for it if I want to pull out some roses. Which I might.
What has happened to some of my plants is they look nice when I buy them but the stems aren't hardy the first winter or really what happens they start growing and we have a late freeze. It is like starting all over again. You would think cutting them way back should bush them up but that didn't really work for me besides Wysteria lane. Maybe I wasn't ruthless enough.
Before you do as I did and pull them out, I would hope for some more members to post their experience. They may have a way.

ElP, are you able to determine your zone from this map?
https://www.plantmaps.com/inte...

No problems with nematodes here luckily. Peach leaf curl yes, aphids yes, slugs and snails yes, Powdery mildew yes, thrips yes, Fire blight yes... but not nematodes!

I have taken to reducing watering to all Buddlejas and see what happens: while soil drainage here is excellent this really looks like a rootball issue to me and it's better to dry the soil a bit. Rain is already expected starting on Sunday though.