September 23 stands close to one of the year’s great turning points. In the Northern Hemisphere, daylight is retreating, shadows stretch farther across the garden and plants begin responding to longer nights. South of the equator, the same celestial threshold opens into spring, carrying buds, nesting activity and a fresh surge of growth.

This date also gathers three remarkable stories of observation: an expedition returning with pressed plants and contested knowledge, a planet found almost exactly where mathematics said it would be, and a nutrition pioneer who insisted that agriculture should be measured by the health it creates. Together, they ask a surprisingly practical question – what do we notice, record and choose to grow?

September 23, 1806 – The Expedition That Returned with a Continent in Its Notebooks

On September 23, 1806, the Lewis and Clark Expedition arrived back in St Louis after more than two years of travel across western North America. Its official aims included mapping routes, studying geography and documenting plants and animals, but its notebooks also reveal landscapes far from empty or unknown. The expedition crossed territories shaped over generations by Indigenous burning, harvesting, hunting and plant knowledge.

Meriwether Lewis collected hundreds of botanical specimens, although floods, damage and poor storage meant that only part of the collection survived. Plants such as bitterroot, camas and buffaloberry entered Euro-American scientific records through the expedition, but they were already foods, medicines and cultural resources for the peoples who lived with them. The most useful reading of this history therefore replaces the language of botanical “discovery” with a more accurate picture – observation depended on local expertise, and scientific names arrived long after human relationships with these plants had begun.

The surviving pressed specimens still matter because herbarium sheets preserve evidence. They allow researchers to compare past and present distributions, check identities and sometimes study changes in flowering time or plant chemistry. A garden notebook can never become a continental herbarium, yet it works on the same principle: a dated record turns a passing impression into information that can be compared next week, next year or decades later.

For today’s gardener, the clearest lesson is to study a plant in its setting before moving, naming or managing it. Record soil moisture, exposure, neighbouring species and flowering time, and choose locally appropriate native plants from responsible nurseries rather than collecting them from the wild. A plant is not merely an object for a border – it belongs to a web of climate, soil, wildlife and human knowledge.

Garden Inspiration – Start a useful garden record

  • Photograph the same bed or tree from the same position once a month.
  • Note first flower, first ripe fruit, first leaf colour and first frost.
  • Record rainfall or irrigation alongside pest and disease observations.
  • Add the source of seeds and plants, especially locally adapted varieties.

September 23, 1846 – Neptune, Found by Following a Disturbance

On the night of September 23–24, 1846, Johann Gottfried Galle and Heinrich Louis d’Arrest observed Neptune from the Berlin Observatory. They looked where the French mathematician Urbain Le Verrier had calculated an unknown planet should be, based on irregularities in the orbit of Uranus. Neptune appeared within about one degree of the predicted position – an extraordinary demonstration that an unseen cause could be inferred from its effects.

Gardens are full of smaller versions of that reasoning. A pale leaf, one-sided growth, an unexpectedly dry patch or the disappearance of a familiar pollinator is not merely a flaw to correct – it is evidence. The calendar adds another layer. Near the September equinox, rapidly changing day length becomes a dependable seasonal signal, even when temperatures fluctuate from one week to the next.

The practical habit to borrow from astronomy is simple: investigate patterns before reaching for a remedy. Check moisture below the surface before watering, examine both sides of damaged leaves before treating pests and compare several plants before assuming a disease. Just as Neptune was found through a repeated deviation rather than a single glance, garden problems are diagnosed more reliably through trends than through isolated symptoms.

Garden Science – How do plants measure the shortening day?

Plants use light-sensitive proteins, including phytochromes, to register the duration of light and darkness. This photoperiod helps regulate flowering, bud set, growth and dormancy. Many plants are especially responsive to the length of the uninterrupted night, which is why bright artificial light after sunset can alter normal seasonal behaviour.

  • Short-day plants initiate flowering when nights exceed a critical length.
  • Shortening days can help woody plants slow growth and prepare for cold.
  • Temperature still matters, but day length is the more predictable annual cue.

September 23, 1880 – John Boyd Orr and the Garden as a Food System

John Boyd Orr was born in Kilmaurs, Scotland, on September 23, 1880. Trained as a doctor and known for his work in nutrition and animal science, he argued that hunger was not simply a shortage of calories but a problem linking health, poverty, farming and public policy. In 1945 he became the first Director-General of the Food and Agriculture Organization, and in 1949 he received the Nobel Peace Prize for his efforts to connect adequate food with peace.

His central idea remains strikingly modern: agricultural success means little if people cannot obtain a varied, nourishing diet. The same principle can reshape a kitchen garden. A large harvest of one crop may look impressive, but diversity spreads risk, extends the picking season and supplies a wider range of foods. Herbs, leafy vegetables, legumes, roots, fruits and edible flowers can turn even a modest plot into a resilient miniature food system.

The useful September lesson is to review the garden by meals rather than kilograms. Which crops were eaten fresh, stored successfully or shared? Which produced more than the household could use, and which disappeared too quickly? Next year’s plan should favour crops that suit the soil and climate, earn their space in the kitchen and contribute either food, fertility or habitat.

Seasonal Tips – What should gardeners do around September 23?

In temperate Northern Hemisphere gardens:

  • Harvest dry beans and mature seeds before prolonged wet weather, then dry them thoroughly before storage.
  • Sow a suitable cover crop on empty beds, or protect soil with compost and an organic mulch.
  • Plant spring-flowering bulbs once conditions begin to cool, following the depth recommended for each species.
  • Keep newly planted trees and evergreens watered during dry spells – roots continue working after top growth slows.
  • Leave healthy seed heads and some hollow stems standing for birds and overwintering insects.

In temperate Southern Hemisphere gardens, use the date as a spring checkpoint: watch for late cold snaps, harden off tender seedlings gradually and renew mulch after the soil has warmed.

Wildlife Note – Should Every Autumn Stem Be Cut Down?

Not yet. Standing stems, seed heads and leaf litter provide food and shelter at a time when tidy gardens can become ecological deserts. Finches and other seed-eating birds visit mature flower heads, while many invertebrates overwinter in stems, under leaves or close to the soil surface.

Keep paths clear and remove diseased material, but leave selected patches undisturbed until consistently mild weather returns. Late flowers such as asters and ivy can also provide valuable nectar where they are appropriate and non-invasive. A partly untidy garden is often a better connected habitat.

What to Observe Right Now – The Garden at the Balance Point

  • Compare sunrise and sunset positions with where they appeared in midsummer.
  • Look for the first tree or shrub to change colour, and note whether drought, shade or species explains the difference.
  • Watch which late flowers still attract bees, hoverflies and butterflies during the warmest part of the day.
  • Notice spider webs made visible by dew and birds pausing to feed during migration.
  • In the Southern Hemisphere, look for swelling buds, fresh shoots and the first insects visiting spring blossom.

Looking Ahead

September 23 reminds us that good gardening begins with evidence and becomes meaningful through care. A dated notebook can reveal environmental change, a careful diagnosis can prevent needless treatment and a diverse food plot can connect soil health with human health. The future garden will need all three habits – observing closely, respecting inherited knowledge and growing for resilience rather than appearance alone. Begin with one record, one better question and one plant chosen for the wider living community around it.