Nell was eight years old and she had a tin. It was a round biscuit tin with a sailing ship on the lid, and inside it were fourteen runner beans her grandfather had dried the summer the water butt cracked. The beans were Hollow Crown, a black-seeded kind that climbs eight feet up a cane. They were three summers old and they were the last of his crop.

That crop had come in first at the A and P show at Wānaka three years running. Three years is not a long time. It is also the whole life of a bean seed, and her grandfather had said so more than once. Nell's job that week was to find out whether the beans would still grow, because the seed shelf at the library would not take seed without a test written beside it.

You cannot ask a seed, so ten of them went onto a square of damp kitchen paper. She folded the paper over them, slid the packet into the clean tin, and left four beans on the shelf where they had been since the summer. Then the lid went back on. That was the rule, and the rule came from her grandmother, and it went back further than Nell could remember. The lid goes back on. The tin goes in the cupboard, cool and dry, out of the light. Nell stuck a strip of masking tape down the side and wrote 4 March on it.

On the fifth day there was nothing in the paper but a wet grey shadow where a bean had been. On the seventh day two beans had split along the seam and showed a white knee the size of a thumbnail. By the ninth day the paper was slick. Two beans had green on them. The other eight had gone black at the tips and were soft if you pressed them, and the tin smelled of vinegar.

Her grandmother came in with the flour and stopped in the doorway with the lid still shut. She opened it and put her nose in. “Damp, not wet,” she said. “And air. A bean drinks faster than anything alive, and it breathes while it drinks. Shut it up wet and there is no air in there at all.” Nell wrote 2 out of 10 in the notebook and put a line under it.

Her grandfather said three summers was too long and the seed was dead, and he was not being cruel, he was being certain. So Nell took the last four beans off the shelf and did it again in the same tin, on the same paper, with water out of the same cold tap.

She folded the paper and put the beans in and left the lid leaning against the side of the tin instead of on it. Then she set the tin on the kitchen sill where the sun comes up at seven. On the fifth day one bean had a root curving round and down. In June the four were a foot high and each one had pods setting, and the seed shelf in the Wānaka library still had a gap on it where the beans should have been.

Her grandfather counted them twice. Then he read the first number in the notebook and then the second one, and he did not say a word about the summers.

The seed shelf wanted a full tin and a figure of at least seven in ten. The tin held four beans and the figure was four in four. “Four in four is not a number,” the shelf keeper said. “It is four.” So the four went into the plot at the top of the garden, one bean to a cane, and the eight that had gone black went to the bottom of the compost heap, and Nell washed the tin and set it upside down on the drain to dry.

She put new tape on the side and wrote 4 March on it and then wrote 0 underneath, because the tin was empty. Under the 0 she wrote two lines. The first said 2 out of 10, lid on. The second said 4 out of 4, lid off. Same tin. Same paper. Same beans, three summers old.

She had no figure that was fair, because she had run the test twice and cooked half the seed on the first morning, and a rotted seed is not a seed that failed to grow. It is a seed she drowned. In June the four were a foot high and each one had pods setting, and the seed shelf in the Wānaka library still had a gap on it where Hollow Crown should have been.

The tin stands empty on the shelf with two numbers on the side of it, and Nell is not yet sure which one is true.