Fall's Lament(edit)

[Potshots]

It’s too late-
the leaves and you are gone,
no longer living
in summer’s forgotten dream.

I enjoy the thought presented and how it lays the foundation for the rest of the poem. The second and last lines can be pared down and more elegantly worded to convey your meaning. Maybe even simply removing “in” from “in summer’s forgotten dream.” would be a good change. The second line may require more thought, but condensing it or transitioning to an analogy/metaphor would be more impactful however you feel best achieves that.

The trees’ grey arms still reach-
false bright of blue,
sun’s promise, slips
through spindled fingers.

The first line comes across a tad too literal and can be worded more abstractly. I want to know it’s a tree without being told it’s a tree. The rest I enjoy. I don’t know that the comma in “sun’s promise, slips” is grammatically required or that it serves a necessary artistic purpose.
 

I envy the tender shoots 
deep in soil’s quiet night,
gentle roots cradling
lost blood and bone.

I enjoy this stanza a lot, but I think it would work better without “I envy”. The first line may read something like, “Blessed, tender shoots”.

 
I lay my head to rest 
against your stone forever
promising to tend your flowers
with no hope of spring.

This could read,

“I lay my head
Against your stone
Tending flowers
No hope for spring”

Obviously that is not an ideal composition but it essentially loses no information. This stanza just needs a bit of simplification, and I believe that being less literal would help a lot.