pale pinks and blues change color thru the day.. based on the intensity of the sun ...

or more precisely i should say ... your eyes perception of said color changes ...

in the olden days.. when we had real cameras.. those peeps could explain how and why ...

but a plant that looks pinkish at noon.. could easily look bluish at dusk .. depending not only on light intensity.. but on how wide open your pupil is .. and the color of the sunset ..

if you look at the pix you provided.. notice when the pic was taken ... and how the color changes ...

or better yet.. look at these pix of the pumilla ... see how they vary ... and see if you can notice when the pic was taken ...

https://duckduckgo.com/?t=ffnt&q=astilbe+pumila+chinensis&iax=images&ia=images

and finally .. part of how it all works depends on how the sun tracks thru your garden... and how your garden affects light intensity ...

imo.. just try one of each.. and find out which you prefer.. you really dont need 3 of one kind ... thats just lazy gardening ... lol ... can you tell im a collector.. not a grouper of plants ....

ken

Amethyst would bloom earlier (May- June) because it is an Astilbe x arendsii. It would form a clump.

Heart and Soul & Pumila are A. chinensis so would bloom later. The blooms of Pumila stand about 12" whereas Heart and Soul has taller flowers of about 32".

Soil must be rich and moisture retentive but A. chinensis can handle drier and sunnier sites. Not dry and sunny just more so than A. x arendsii.

Out of these I only grow Pumila . It is rhizomatous but never aggressive and blooms July though Sept.

They do appear to change colour depending on light exposure and time of day. Pinker in sun, more purple/lavender in shade.

"you really dont need 3 of one kind ... thats just lazy gardening ... lol ... can you tell im a collector.. not a grouper of plants ...."

Lol Ken! I am a collector and a grouper. Definitely not lazy!!!

grouping was just marketing mumbo jumbo from landscaper who needed to get rid of all the excess stock they mistakenly bought.. lol .. and the designers they use to sell all their stuff ..

i see no downside to groping the plants you divided off your own stock plants ... thats just plain smart .. but buy more than one of any given plant.. bah ..

of course.. thats how i ended up with 1650 DIFFERENT hosta.. lol ..

ken