With regard to strategies to protect a seedling from cold, you just need to invert a bucket/bottle over the plant at night. Most of the protection is from trapped warm air from the ground. Heat that has accumulated in the daytime, and also heat from organic decomposition in the soil. Any bucket will do that. But some of the protection is from the insulating capability of the bucket. For a given thickness, plastic, wood, and paper are roughly similar in insulation capability. Glass is worse per unit thickness, but any glass cover is going to be a lot thicker. Metal is a factor of 10-100 worse. You won't find any thick paper or wooden buckets, and most any glass cover will be small (trapping less heat from the ground) so I'd do plastic. If you're trying to protect a whole bed, then a plastic tarp weighted down at the periphery is the way to go. I just did that en masse in our recent horrific Texas freeze. I find it amusing when people try to protect small fruit trees from a freeze by wrapping them in a tarp. That doesn't work at all. When you put a blanket around yourself, it keeps you warm because you generate heat, and the blanket keeps it in. Trees and plants don't generate any heat.

if i can subtract properly.. you planted in during the last weeks of august ... was your OH as bad as my MI them.. near hundred degrees.. and 70s at night??? severe stress ... even damaged leaves can process light into energy.. so dont go cutting them off ... they will fall off in a month or so anyway ... just insure you are watering deeply into the root mass planted... deep into fall ... and next time.. hold the potted plant until.. well.. about now.. as falling night temps are a relief period from whatever the day may hold ... just because you get your grubby mitts on a plant.. doesnt mean its planting time .... its good its deciduous.. so all the uglies will fall off in a few weeks ... and if properly planted and watered.. it should leaf out just fine next spring ... i like the primer below ... if you have that bad OH clay ... and are concerned about how you planted ti.. we could discuss it if you wish .. ken https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub ps: its kind of a big plant.. to be that close to the house ... if you have the cultivar name.. you could narrow this down a bit... scroll down and look at future potential .. https://duckduckgo.com/?t=ffab&q=ninebark&iax=images&ia=images

Overall it looks Ok. It appears to have a mild case of SADS

@tapla (mid-Michigan, USDA z5b-6a) Hi Al, I've potted up my citrus plant. The old soil is very hard, but I'm hoping that the new situation will be okay until next March/April when I will transplant the plant into gritty mix. Since repotting, the soil seems to be staying damp for a longer time (I previously went about 6-7 days between watering). The plant seems fine so far and its lemons are still visibly getting bigger. As a thank you for your advice, I wanted to share a picture of my citrus plant: Inside the larger pot, the plant is in a plastic pot that rests on a generous bed of stones. The plant sits on a long windowsill in front of a high (1.5-story) bank of SE-facing windows with a wide, unobstructed view of the sky. In the picture (though it might be hard to see), there are about 6 medium- to large-sized lemons visible (and not visible, about 8 marble- to medium-sized lemons on the other side). When I bought the plant at the end of March, it had two lemons on it and I've had two flushes of flowers since then. Truthfully, the shape of the plant needs work, but I can't really prune it without cutting off some lemons right now (although maybe that wouldn't be a bad thing to help the plant focus its energy). In any case, I have the impression that the plant is healthy and happy, which gives me a lot of satisfaction. If you have a moment, I would still appreciate hearing your thoughts on how water hardness bears on the necessity of using a fertilizer with calcium and magnesium. Will plants take up the calcium and magnesium from hard water such that fertilizer with calcium and magnesium is optional? Thanks again and have a good day!