The Lunar Timber Calendar: Sign and Waxing Moon

The timber calendar stands apart among the three specialty calendars. The hair calendar and the gardening calendar each take exactly one field from the table — the zodiac sign. This one takes two: the sign plus the lunar day number, and the latter introduces a correction for phase. That makes it look like the most "precise" of the three, although it is no better grounded than the others.

Which values are used

Two fields of the main table feed in:

• the Moon's zodiac sign — sets the base rating;
• the lunar day number — acts as a phase marker.

Not used: the illuminated fraction, the Sun's sign, the time of entry into the sign.

The second rule: the waxing-Moon correction

The second rule lowers the sign's base rating by lunar day number. Numbers 1 to 15 correspond to the waxing Moon, numbers 16 to 30 to the waning Moon.

• A number above 15 (waning Moon) — the base rating from the sign applies unchanged.
• A number from 1 to 15 (waxing Moon) — the rating is lowered by one step.

It steps down a ladder: "favourable" becomes "neutral", "neutral" becomes "unfavourable", and "unfavourable" stays "unfavourable", because there is no step below it.

From this it is clear that the second rule is strong: it rules out roughly half the month (days 1–15). On waxing days no favourable sign survives in the table at all.

Base sign ratings

This table applies on waning days; on waxing days the one-step lowering is applied to it.

The right-hand column has no "favourable" left at all: on waxing days the table recommends felling in no sign whatsoever. That is a consequence of the stepwise lowering, not a separate rule.

Why the tradition prefers the waning Moon

The traditional reasoning is physical: sap is said to move in the tree, and on the waning Moon, as the Moon wanes, that movement supposedly coincides with a downward flow towards the roots. Hence the general advice to fell after the full moon rather than at the new moon.

A direct caveat is needed here. No reliable, reproducible measurement links lunar phase to the density, moisture content or shrinkage of timber that is known to this editorial team. There is no biological mechanism that would explain one: sap movement is driven by soil temperature and moisture, not by the Moon's position in the sky.

It is also worth remembering that felling is one of those jobs where a mistake costs the most: a felled tree does not grow back. If the calendar is followed only for consistency with tradition rather than for results, it is more sensible to postpone work according to the weather than to hunt for a lunar date.

How a sign change interacts with the phase

Sign and phase run on different periods, so the phase can change within a single sign. That means that within one block of the table the final rating under the same base rating is first "neutral" and then "favourable" — simply because the lunar day number has crossed from 15 to 16.

When reading the table it helps to look at both columns at once — the base rating and the waxing-adjusted rating. If you have a choice of two dates within one sign, compare the lunar day numbers: 16 or above beats 1–15; where the numbers fall on the same side of 15, the dates are equivalent. Watch out for the new-moon rollover (30 → 1): there the later date is worse, because it falls on the waxing Moon.

How to use it on lunar.day

The dedicated page opens from the main lunar calendar and shows the month with "Day rating" and "Tradition's advice" columns. The data is computed for the selected city in its own time zone.

The lower part of the page links to the hair and gardening calendars. Do not mix their rules: in hair and gardening the sign is used without a correction, here it is corrected for phase, and the same date will score differently in different calendars.

If you switch the zodiac system, the "sign → rating" lookup table does not change: the rules are written for the tropical zodiac, and the page always computes from it. But the sign of a specific date will change when you switch — and with it, that date's final rating.

Summing up

The timber calendar is the only one where two rules combine: the sign gives the base rating, and the lunar day number lowers it by one step on waxing days, numbers 1 to 15. The correction is strong — on those days no favourable sign remains at all. The traditional reasoning is physical, sap moving towards the roots on the waning Moon, but no reliable, reproducible measurements of timber density or moisture by phase are known to this editorial team. Rule complexity does not make the calendar more accurate: it only looks better justified — which is more dangerous, because a mistake in felling costs the most.