I start with a fairly swift line for line equivalence, just to get the feel of it.
Late August given heavy rain and sun
Late Jan, given weather hard or clement
For a full week, the blackberries would ripen.
The snowdrops would be out…
At first, just one, a glossy purple clot
At first just a little star of uninspiring leaves
Among others, red, green, hard as a knot.
Thin, not strong enough to survive
All sorts of things need changing, I know.
After a little thought, more memories of snowdrops and a visit to the clumps growing in the garden, a change of the second line to
The snowdrops would begin to blossom
More thought makes me realise that I need to get the first appearance of the snowdrops before I move on to blossoms, just as Heaney notices the first hard blackberries. So I need to go back a month.
Late December, given weather hard or clement
The snowdrops would begin to send
Their first small stars of uninspiring leaves
Hardly strong enough to survive;
I also want to mirror Heaney's gentle rhymes and almost-rhymes. So 'send' is fine. I was unsure of 'clement' to begin with. I still think it sticks out a bit - but it is what I mean so perhaps I should stay with it. 'Uninspiring' is a bit, well, uninspiring. But it's what they are at that stage.