What to write in a garden journal (and what is a waste of ink)

Gardening has an unusually cruel feedback loop. You make a decision in March and find out whether it was any good in August — by which point you have made forty other decisions and have no idea which one was responsible.

A season is a single data point. And memory quietly rewrites it, almost always in the direction of the story you have already decided to tell. The tomatoes were fine. The squash did badly because of the weather. You are sure you planted the beans earlier than that.

Written notes break this. Not because they are precise — they usually are not — but because they are dated.

The five things worth recording, in order

1. Dates. When you sowed, when it germinated, when you planted out, when you first picked something, when you pulled it up. Almost everything else can be reconstructed from dates. Almost nothing can be reconstructed without them. If you only ever record one category, record this one.

2. Failures. The instinct is to record successes, and it is exactly backwards. A success puts food on your plate, which is its own reminder. A failure leaves an empty patch of soil that you will have forgotten by November. Failures also carry more information — something went wrong, and there is a cause to find.

3. Weather that was unusual. Not a daily weather diary; those never get filled in past week three. Only the events that will explain something later. The late frost. The three-week dry spell. The week of rain that landed exactly when the squash was flowering.

4. Varieties, exactly. “Tomatoes did well” is worthless in February. “Cherokee Purple split after every rain, Sungold did not” is a decision you can act on. This is the single most common gap in abandoned journals — people record the crop and not the variety, and the variety is usually what actually differed.

5. What you changed. If you changed three things at once, you will never know which one worked. You will probably change three things at once anyway, because that is how gardening goes. Writing them down at least lets you notice you did it.

What is a waste of ink

Daily entries. Anything that requires a sentence when a date would do. Elaborate weather logging. Beautiful layouts you are afraid to write in — genuinely, a journal that is too nice to scribble in is a journal that will not get used in muddy hands in April.

And copied-out advice. If you are writing down what a book told you, you have a reading notebook, which is a fine thing but a different one. The point of the journal is that it contains information that exists nowhere else in the world: what happened in your garden.

The one rule

Write it the day it happens, or accept that you are writing fiction. A journal filled in from memory in November is a pleasant read and worthless as data. The entry can be four words. It cannot be four months late.

The page that pays for the whole thing

If you keep nothing else, keep a map of where things grew.

Crop rotation is one of the few genuinely free interventions in vegetable growing. Soil-borne disease and family-specific pests build up where their host keeps reappearing, and moving the crop breaks the cycle at no cost. But it depends entirely on knowing where things were last year, and by the following March you will not remember. Nobody does.

A rough sketch with four labels on it, made in July, is worth more the following spring than anything else in the book.

The principle is simple enough to hold in your head: do not grow the same plant family in the same ground in consecutive years. Tomatoes, peppers and potatoes are one family. Cabbage, kale, broccoli, turnip and radish are another. Peas and beans are a third.

Four beds and four family groups gives you a four-year cycle, which is comfortably enough for most soil-borne problems. But every bit of it depends on a scrap of paper made last July.