To understand our changing climate, we need to examine records of earlier variations. Some of these – dendrochronology, or the Greenland ice-cores – can be wonderfully precise. Others, like the journals of eighteenth-century phenologists, are valuable, but more difficult to interpret. For the farmer and gardener,  one of the most interesting historical documents is Thomas Tusser’s  “Five Hundred Points of Good Husbandry”, first published in 1557. (And written in verse, of course. You wouldn’t want to carry an expensive book around the farm in your pocket, but heroic couplets can be carried in the head). Tusser tells his reader what to do, month by month: reassuringly, much of that advice is still relevant.

I have recently been asked how to calculate the best date for planting potatoes. One can go by the instructions on the packet – end of February for first earlies, early March for seconds, and late March for main crops. Wouldn’t have worked this year, would it? Or one can get all technical: start planting when the soil temperature is 6 – 8 degrees C, and the risk of frost will be past within a fortnight. Damn: I seem to have mislaid my soil thermometer.

Now, for obvious reasons, Tusser has little to say about potatoes. However, his common sense approach can be adapted to situations he could not have foreseen.

“In Maie get a weed-hook, a crotch, and a glove, And weed out such weeds, as the corn does not love.
Slack never thy weeding, for dearth nor for cheap, The corn shall reward it, ere ever ye reap”.

Because, of course, it is best to get on top of the weeding before the dandelions and bindweed have sent down deep roots. And the growth of weeds indicates that the soil is warm enough for planting your spuds. And unless you are very competitive about your new potatoes, this is precise enough, I think.

In May you can sow, or plant out: beans, dwarf and runner: beet, broccoli, Brussels sprouts, cabbage, carrot, and cauliflower: courgettes, cucumber, and kale: marrows, melons, parsnips, peas, pumpkins, radishes, spinach, spring onions, squash, sweetcorn, swiss chard, turnips, and watercress. But sort the weeds out first, please.