Fall equinox and gardening

- by Patricia Hanbidge

September 10, 2025

key points from this story:

• Plants respond to shorter daylight hours.
• Autumn equinox marks harvest celebrations.
• Equinox timing shifts yearly from leap years.
• Auroras often visible after autumn equinox.
• Fall equinox celebrated globally with traditions.
• Gardeners prepare for winter during autumn.

The fall equinox is officially the first day of fall. However, this does not necessarily mean that it is actually autumn in your garden. The word “equinox” means “equal night” in Latin. So when we have both spring and autumn equinox, the daytime and nighttime hours are very close to equal. If the earth took exactly 365 days to revolve around the sun, then the date of our spring equinox would not change from year to year. The earth’s orbital period takes about 365.25 days to complete one orbit around the sun. The standard Gregorian Calendar has 365 days in one year and every four years, there is a leap day to account for the extra quarter day. Because of each quarter-day, the equinoxes (and solstices) occur about six hours later each year. When it is a leap year, the extra day makes the date of the equinox earlier. The different time zones, which further complicate the actual date of the equinox. This year, the fall equinox will be on September 22nd.

In the garden, the plants do not realize the exact moment that the sun crosses the equator, but they certainly do realize that the days will be getting shorter, the light exposure will be decreasing and the temperatures will be cooling. This all tells the plants that they need to complete their lifecycle and prepare for the long winter rest. Around the world, there are many autumnal equinox celebrations that include cultural festivals, religious holidays and other more nature based activities. There is a common theme that is often seen as part of these celebrations that includes giving thanks for the harvest, preparing for the coming winter and of course celebrating the balance between light and dark.

In Japan, Buddhists honour their ancestors during Higan, which is a six-day holiday falling on the equinoxes. In China and Vietnam, one might participate in the mid-autumn festival with mooncakes and lanterns that symbolize unity and togetherness. Some activities you might be interested in to help celebrate this time is by going on scenic drives to enjoy the fall foliage, go apple picking or visit a local pumpkin patch. Prepare and share special meals that feature fall flavours like roasted root vegetables, soups, apple pies or perhaps making pumpkin pie spice. Bring the beauty of fall indoors by making wreaths or decorating your home with autumn colours.

An interesting fact is that the autumn equinox signals the start of the time where you can often see the aurora borealis. These auroras are caused by the interaction of the solar winds with the Earth’s magnetic field. The solar winds are particles of plasma that are escaping from the sun and moving into space. Due to the axial tilt of the Earth, at this time of year the solar wind from the sun is able to reach the Earth’s atmosphere more easily through our geomagnetic field. These disturbances are strongest around the spring and fall equinox. These particles collide in the Earth’s magnetic field with different elements in the air like oxygen and nitrogen and then these particles eventually will release photons of different wavelengths that provide the different colour of aurora or northern lights that we can see in the sky.

As gardeners, we plant spring flowering bulbs, harvest crops and prepare our soils for winter. We may also prune perennials, divide plants, rake leaves, plant fall crops and generally prepare to take a break from our summer gardening chores. Our flannel and fleece reappears and we often wonder at the coolness of the evening air. Already, I have found myself waking a bit later as I am always attuned to when the sun rises and sets and generally all of the motions of the earth around me. Happy Autumn!!!