Hortus

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About this app

Hortus is a sowing calendar. For any day it tells you the kind of garden day it is - root, leaf, flower or fruit - which way the Moon is travelling, whether it is waxing or waning, and which hours the old calendars mark off. Then it says what the tradition times to that, and where each rule comes from.

Everything is computed on your phone from the position of the Moon. No data file, no account, no network call, and no location: the Moon's place in the zodiac and the height of its path are the same for everybody on Earth, so the only thing Hortus needs from your phone is its clock.

THREE CYCLES, KEPT APART
• The kind of day, from where the Moon stands in the zodiac, changing every two or three days at whatever hour it crosses.
• Ascending and descending, from the Moon's declination: whether its path across the sky is climbing or sinking. This is the planting cycle of the modern calendars, and it is not the phase.
• Waxing and waning, the oldest layer, and the one the old books actually discuss.

YOU CHOOSE THE ZODIAC
There are two ways to measure where the Moon is, they have drifted almost a whole sign apart, and they give a different answer for most days of the year. Tropical signs are the twelve equal signs of the old almanacs; constellations are the real ones on the ecliptic, unequal and fixed to the stars, as the biodynamic calendars use. Hortus asks on first run and never picks for you.

WHAT IS IN IT
• A month grid in four colours, with days that hold two kinds split in two, because the Moon does not change sign at midnight.
• The hours marked off around lunar nodes, perigee and eclipses, with the width of the window yours to set - printed calendars genuinely disagree about it.
• Thirty-six crops, and for each one the next three windows that actually suit it: right kind of day, right direction of the Moon, and in season.
• A garden journal that records the kind of day and the zodiac each entry was made under, so it still means the same thing if you change that setting next spring.
• Thirteen written articles on where all of this comes from.
• A home-screen widget that updates when the day changes, not at midnight.
• An optional evening note about tomorrow.

WHERE THE RULES COME FROM
Every suggestion says whether it stands on a book or on modern practice. Timothy Harley's Moon Lore of 1885, Thomas Tusser's farming verses, Plutarch on felling timber, the French royal ordinances for the oak forests, Hesiod and Virgil on the days of the lunar month, Ptolemy on the triplicities, and the Pennsylvania farm records of 1888 that planted potatoes when the sign was in the feet. The root and leaf days themselves belong to the twentieth century, and the app says so rather than borrowing an authority it has not got.

Where the sources contradict each other, Hortus shows both. Tusser sows peas in the wane and the general rule sows climbers in the increase; Devon would not pick apples in the wane and Plutarch's farmers hurried to. That is what the tradition is actually like.

WHAT HORTUS DOES NOT DO
It does not score days out of ten - no tradition here does that, and a number would be invented. It does not promise a bigger crop, and it has an article saying plainly where the research stands. It asks for no personal data and no location.

Free to install, with ads. A single one-time purchase removes them.
Root, leaf, flower and fruit days, the ascending Moon, and what to sow on each.
Updated on
Sep 14, 2026

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What’s new

Prod v1.0