The speaker looks back on a youthful hunger for land, the kind of person who spent summers digging and turning soil. But in winter, the wish changes. Instead of crops, the speaker hopes for snow, which turns the ground into something almost imaginary: a "Platonic" field, an ideal version of a field, blank and perfect. It is as solitary as a desert, and just as free of weeds.
That's the twist in the poem. The gardener who loved working the earth also longs for the earth to be left alone, clean and silent under white. The final image complicates this calm. A leafless rose stands by itself, tangled in its "barbed canes." It is beautiful in a hard, prickly way, and it suggests that solitude has a sharp edge.
The mood is quiet, spare, and a little wry. There is real pleasure in emptiness here, but also a hint of loneliness and thorns.