Zone 5b Maine October 2024

Hi! I purchased a bunch of shrubs and perennials at a large local garden center over the last 2 weeks. I am newish to gardening (I have grown perennials and annuals, but this was my first time buying shrubs). I have did a lot of research and decided on a few varieties of smooth hydrangea, Hydrangea arborescens. I also got inkberry and Ninebark and one limelight panicle hydrangea. Those seem healthy so far.

When I was shopping, the hydrangeas had some browning and holes in the leaves. I didn’t expect anything deciduous to look great right now- it’s fall in New England, I am in Zone 5b, our temps are dipping into the 30s at night. I asked an employee if they had any concern about the holes and browning on the hydrangeas. They said no; that the leaves were not happy because at the store they water by overhead sprinkler. They said these would come back fine next year and would be happier once in the ground. So I got them. I watered daily for a week in the pots, however when I got a day off and went to plant them, I noticed orange dust all over the underside of the leaves, and some more crispness and dying of leaves. So I stalled and have not planted them yet.

Google tells me this is hydrangea rust. From what I can find, it may only affect smooth hydrangeas and hemlocks? However I am finding minimal information online about how fatal/ bad this is, or how much effort is going to be involved in caring for these plants moving forward. I’m wondering if anyone has experience with this and can help me out. My questions are:

Am I harming my garden by bringing these plants into it? These would be the only smooth hydrangeas on the property, but we are surrounded by natural growing hemlocks (many are sick already due to wooly algeid, but I have one healthy that I was hoping might last awhile longer). Will the rust affect other plant varieties, or is it truly only the smooth hydrangea and hemlock that are susceptible?

If I remove all the live foliage and leaf debris from the plants before planting, and proactively treat them (neem oil?) will that be enough to prevent the disease from coming back next year? Or, if they have it now, am I doomed to battle this forever?

Essentially I am trying to decide if it’s worth planting these or if I should cut my losses. Or maybe just plant them in a less visible spot. I was planning to put these in a new front garden where they would be fairly visible/on display. We don’t get a lot of visitors but ideally I’d have something hardy and reliable there so I don’t have to be looking at sad sick plants.

Here are the varieties that have the rust:
Hydrangea arb. 'Bar Harbor' Smooth Hydrangea

Hydrangea arb. 'FlowerFull' Smooth Hydrangea

Hydrangea arb. “Haas Halo” smooth hydrangea

Also, I got these plants during a fall sale, so everything is marked final sale (50-70% off) and does not come with a guarantee. I maybe should’ve seen this as a red flag, but this was a very reputable and large garden center in my area, so I felt comfortable). In general is this a red flag or typical for plants bought at a garden center? I did reach out to the center for advice and am waiting to hear back. I’m going to call them again but wanted to see if others could offer any advice on this.

Thank you very much!