In my experience, Astilbe do not only tolerate shade, they ARE shade plants. While many "shade" plants will do okay in the sun if given enough water, Astilbe just don't like too much direct sun. A sign of too much sun is definite crisping around the leaf margin, not a change in color.

The Astilbe that have always done best for me got about an hour or two of early morning sun, nothing more. Terrific bloomer, beautiful foliage all season long.
In too much sun, the plant will crisp, yellow and go dormant by mid summer unless you are prepared to keep it watered. A lot.

I don't believe direct vs indirect light has much impact on the plants' chlorophyll. Lots of deep green plants grow in complete shade. Tell Science Guy that your plants likely look anemic because they spent a LOT of energy and soil nutrients while blooming, which your other ones did not.

Astilbe are heavy feeders but mine just get lots of compost and some soybean meal after they've bloomed. Of course, potted ones would need more care.

Since your husband is a science guy, I think he would appreciate this experiment: move one pot to sunnier spot, one to a very shady spot, and leave the last one where it is. In two weeks or so see which one looks better. I'd pick spots where you are thinking about moving them to if possible.

My experience is that astilbe appreciate more shade rather than less. I have mine (also new from bluestone this spring) on the east side of my deck which is on the north side of my house. The one in the most shade is the largest and happiest looking one. The one on the end away from the house gets more sun and is the smallest.

You must be doing something right if you got blooms already. Mine are a different variety and didn't bloom this year.

I agree. I had two Astilbe in the same shaded bed. One that never gets direct sun and one on the other side that got a couple hours of afternoon sun. The one with no direct sun is still there and doing great after several years. The other was always smaller and continued to get smaller until it just gave up. Same soil, same amount of water.

Astilbes like their soil deep, rich, and ACID. They want lots of humus and they want the moisture to be abundant at all times. Mine do best with morning sun to dappled afternoon sun.

I don't think they particularly like being in pots, personally. They're probably root bound, and that means they'll dry out faster than they would if they were in the ground. PLANT THEM! I'd avoid any location that features the blasing hot, westerly sun. It's asking for trouble. Your husband doesn't know what he's talking about (sorry).

I have only one variety that will tolerate a lot of sun and it's Astilbe taquetii. It's "hairier" than the arendsii varieties, the foliage is paler/more mottled but it's TOUGH. It reseeds happily and while I don't love the color of the flowers (that strident fushchia) I "deal" with it because everything else about the plant is so terrific. Mine gets blasting hot, mid day sun from June-late July and it never shrugs... BUT, the bed is deeply dug, the soil is very rich, and I feed and topdress the planting in the fall and in the spring!

Are you in Maine, too?

"I'd pick spots where you are thinking about moving them to if possible."

I've been stressing out about what can handle being planted on the the north side of the house, which gets some morning and afternoon sun. I could have just put some of my 50 or so pots over there! I can't believe I didn't think of that. Do you think its too late in the season to try that?

My plants from Bluestone have done great. I haven't lost anything yet. Most are in 2 gallon pots, with the shrubs in maybe 4 gallon pots. A few got a little fried when it was crazy hot a few weeks ago, but they have new growth. The astilbe (and everything else) were repotted when I got them, maybe May 15? They've all taken off. The astilbe and hosta pots on the ground are actually anchored to the ground by roots. But most of the 50 pots are elevated on a piece of plywood resting on saw horses.

Yes, I'm in Maine, pretty much right over the border from Portsmouth. Our native soil is really horrid. Sticky clay with little bits of smashed up ledge. Zero drainage. I tested the soil a few years ago and it came out slightly acid. The plants are in pots right now, so they are getting whatever the potting soil companies put in there. We do have blueberry bushes growing wild, so I assume the native soil is acid.

Everything is in pots because my final grade and loam (and lawn and flower beds) have not been done and I had an actual physical need to buy plants. The landscaping was supposed to be done first thing this spring. I put all the plants I got into bigger pots and diligently took care of them. They are SUPPOSED to go in the ground before fall. But we are no closer to that than we were this time last year. At this rate I am facing somehow over-wintering 50+ pots. Let's say I am NOT pleased about this. DH and I have had major arguments about the landscaping in general (we are in a nice neighborhood, and the yard is a blight with piles of fill scattered about and tons of weeds.). He basically wants me to hand him $15k and say "have fun spending it on a lawn". I want a plan (what machines need to be rented and when, how many days, how many yards loam, how many yards fill, how deep will the loam be for the lawn, how will be flower beds be constructed, etc.) with prices. Him? Not so much. So he stalls (after all, stalling means no work for him!). And I fume.

I can't just let him run with it. I learned when we built the house not to let him make financial commitments without reviewing it with me. He prefers to just start without a budget, plan or estimate of cost. He won't even ask someone what they are going to charge before they do the work. I got quite a few surprise bills when we built the house, all a result of this behavior (learned from his mother, who thinks asking the price is anything is embarrassing). Yes, I could try to arrange getting it done myself. But I don't have the time (I have a 4 hour round trip commute everyday) and I shouldn't have to, since DH is a licensed contractor. (Yup, that's right).

So, that is the saga of why I have a "pot ghetto". The weekend is here. Time to talk to DH AGAIN about the landscaping.

I'm not too very far from you (northeast), so I understand your soil and I also understand your frustration with the grunt work required to plant anything! I double dug every single bed in our yard and the running joke is that I've touched every single rock that comprises the walls and the edging.

Actually, your clay soil with minimal drainage is a pretty good start, believe it or not! You need to dig and turn in lots of compost down to a depth of about 15-18" and then water it heavily to settle the soil. Then plant. The moisture retentive nature of the clay will be a benefit, but you must add lots of organic matter to absorb the water and provide nutrients to your plant material.

You're right, the native blueberries indicate an acid soil. And fall is a great time to undertake landscaping. Have you contacted any of the local people for ideas/plans? I urge you to do so... I sense discouragement and I hate to see that; there are so many very talented people in the area who could get you rolling in a positive direction and help you break down the project into manageable morsels.

Take a deep breath and contact a professional designer; it will help you a lot!

Looks like you have bigger issues than how much light Astilbe need!

If you don't think the landscaping will get done, you'll have to work on the overwintering problem, first. Is it possible to 1) find an area in your yard where you know for sure you'll eventually have beds, 2) dig that up, 3) dump in a load of decent loam and 4) heel those plants in for the winter? Those that aren't rootbound, if any, could even be sunk into the ground in their pots.

Then you'll have to start compromising with Science/Contractor Guy. You can find time to get a garden plan worked out, indicating what is to go where. Map out everything. Then work out a budget and rough timeline.
If he's a contractor, one would think he's got a fair grip on building materials, or what local supplier has good prices. How else does he stay in business? So it's just the price of garden soil, compost etc that'd have to be sorted out. Surely, you have time for a few phone calls.