I don't have JPW but I have valerian that, both online and everyone at the plant swap I received it from, should be planted in full sun. Mine seems to wilt in the afternoon sun it receives. I often think it'd be better in the garden bed opposite to its existing location, which receives morning sun and afternoon shade. This might be the same. It sounds like you have more than one, and, as ken_adrian has often advised (and I've often followed and had success), move some, leave the others and see what happens. If the ones in a shadier location make it you know the answer :)

They do not like intense afternoon sun. They like morning to early afternoon sun. I would move them and keep them well mulched and watered until established.

My Joe Pye in zone 4 is planted in full sun and does very well. It outgrew wilting once it was well established.

I had them in z7 in full sun mulched with old stalks and other perennial clippings. They did quite well. On a hot day their leaves would droop but bounce back in the evening. I got the ipmression that with established plants the wilting/ drooping is a way to save water.

They need at least 3 years to establish a deep root system, so yours still needs some help

They grow wild down at the lake and in a very wet area. Maybe they need a lot of moisture?

I had Joe Pye weed in full sun for a while. I grew it from seed in the spot where it was located, so I didn't have to deal with transplanting issues. Mine was entirely too happy there, and I ended up ripping it out before it smothered its neighbors. Joe Pye is a native wetland plant, so it does best with consistent moisture in full sun. My spot had a fine-textured soil with lots of organic matter and mulch, so it didn't dry out. You could move it or give it shade in the hottest part of the afternoon until it has adjusted a bit or just keep the soil there well-mulched and very damp by watering deeply and slowly. You can't kill this plant with overwatering.

I have mine in full sun, average soil. They do droop mid-day on hot days sometimes but perk up later in the day.

Thanks everyone!!

I really want to grow it in this spot, because of all the butterflies that are on it later in the season, and I can see it up close and personal from this window.
I think I'll live it there and work on making the soil better, and mulching, and maybe giving it some kind of shade in the afternoon, until it's established.
Thanks so much!

Mine droop almost every sunny or hot afternoon....I've had them in morning sun, part shade & full sun...all of them drooped in the heat of the pm. Only on very cool days do they not droop. And, I would say mine are pretty happy, because they have seeded themselves EVERYWHERE.
I just potted up some big ones to use on the patio for something big, cheap and easy...they are keeping me busy with the watering! I try to give them a great big watering each morning, or the night before if I'm going to be busy in the morning.
As long as I keep them watered, they perk back up in the cooler temps of the evening.
They a bit too much work for me, but I'm going to put up with it this year. If I had a moist spot, they would be much happier, but I can't imagine the seeding I'd have THEN.

it figures... in the other JPW post.. i said i never saw one in my z5.. and here are you folks blathering on about how you have grown it for decades .. care free ... crikey.. lol

ken

My wintersown plants did well in full sun zone 5b- 6a at my old place. They LOVE consistent moisture and that is the key!! I mulched mine with straw and grass clippings (left to dry first). Can't wait to get more started for the new gardens :O

BTW Valerian (Valeriana officinalis) and Joy Pye Weed (Eupatorium spp.) are from different genus/species/families and one has nothing to do with the other :)

Vera

Mine only emerged maybe 10 days ago, but once up are growing like crazy. I've never seen mine wilt and they're in full sun.

Kevin