There Is No Death

[Achebe]

Hi Mac - as this is 'Mild', the expectation is for slightly harsher crit. 
You'll need to work on your images and make them more consistent.
Also, it helps if you stick to one image and develop it rather than flit from one to the other.
Good luck.

There Is No Death
 
Blow, blow, wintry diamonds, .....snowflakes fall, it's the wind that blows. 'wintry diamonds' isn't evocative. Diamonds are not wintry, so the two words don't create an image together, and the effort just comes as trying to hard to say 'snowflakes' in a poetic way.
cloak the earth in death, ...cliched image of snow as death.
in dust, we slumber through the night, 
and wait for summer’s breath. .... too many conflicting metaphors. 'Night' = death, so 'Death' = resurrection. But since you're waiting for 'summer's breath, you have 'Summer' = resurrection. So I'm not sure what a winter's day will be. Purgatorio?
 
While in repose my dearest, ...this address to a Beloved seems arbitrary - you do it at two places in the poem, but then forget about her in the rest
I shall fertilize the earth, ...'fertilise' is not a good choice of word, since it brings to mind other ways that you can possibly do it (I have a lurid image in my head of a man sitting on his haunches in the snow, thank you)
like burning wood sends smoke to sky, ....you're basically saying 'when I'm dead I'll decompose into smaller molecules just like wood burns and turns unto smaller molecules'. this is a trite and pointless observation that doesn't lead to any insight. If you meant to make a deeper point, it's not coming across.
and ashes to the hearth. ...see above

Cogitate my shadow, ...'Cogitate' is an ugly word in a poem as it has too many harsh sounds. 'Contemplate' sounds better.
in bedded rainbow flowers, ...inconsistent imagery. Think about a shadow in a flowerbed?  you mean, I suppose, the corpse under the flowerbed. 'Shadow' for corpse doesn't work here because it mixes up the metaphorical (shadow) with the literal (flower bed) and the end result is confusing.
that echo sunlit afternoons ....light doesn't echo. also, what is 'that' - the shadow, or the flowers?
and gloomy evening showers. ....showers don't echo
 
To Lila I surrender, ....I assume you mean the Hindu concept of Lila, and not the Australian aboriginal word for song ('Lilah' in one of the aboriginal languages, I recall seeing in a video). If so, then I'm not sure the mixing of  the Judaeo-Christian concept of death --> resurrection with the Hindu concept of death --> rebirth makes sense in the same poem.
an enchanted song and dance,
pulsing, throbbing, flowing, changing,
subjective lucid trance.
 
There is no death.
Like rolling waves,
that fear the dreaded shore, ....rolling waves don't fear no shore (edit: if they are already eternal at the core....unclear message)
our lives, evaporating dreams,
eternal at their core.