Harvest festivals are traditionally celebrated around the time of the Harvest Moon which is the full moon that occurs closest to the autumn equinox. It’s an important time in the garden as well as on the farms.
Harvest festivals are thanksgiving festivals, a way of showing gratitude to one’s God or gods for a good store of food to keep the people fed through the lean winter months. Historically, Harvest festival was also an opportunity for the Landowner to give a feast for his workers in recognition of their hard work over the growing season. The first new ale would be drunk and loaves of bread made with the freshly gathered and milled wheat.
So why is the autumn equinox important to your plants? The Harvest Moon usually falls as a full moon at the end of September, but occasionally falls at the beginning of October. It’s at this point in the year that the day and night length are equal. The plants in your garden and allotment will notice the difference as they respond to day length.
Well actually, it’s not quite that simple, not all plants decide to hibernate once the nights become longer than the days; whether we’re having an Indian Summer or an early hoar frost makes a difference too. So, without dumbing down as you’re an intelligent bunch of readers, let’s have a brief botanical explanation as to why the plants in your garden start behaving differently now we’ve reached the autumnal equinox.
It’s important for a plant’s existence that it knows not to lets its seed germinate during winter, when hard frosts would be likely to kill the emerging seedling. Nor would it be productive to flower when there are no pollinating insects around. Neither is a good plan for survival of the species! There are both internal plant factors, such as the production of particular hormones and external factors that affect plant growth. It is the two major external factors that we’re looking at, and they are, as you’ve probably guessed, light and temperature.
Generally speaking, most plants require a certain temperature in order for the seed to germinate and for the plant to grow. Which is why many plants lie dormant or semi-dormant over the winter months. Some plant species require a period of cold to encourage germination of the seed; for example, Tulips. When these plants are grown where the winter is not cold enough, Florida for example, they can be artificially chilled so as to stimulate flowering in the spring.
Photoperiodism, or plants’ response to day length, has been constant over millennia, and it is only recently, over the past couple of hundred years or so, that humans have been successfully able to interfere with the process artificially. Flowering plants are especially sensitive to photoperiodic stimulus; for example, have you ever forced Hyacinth bulbs for Christmas by putting them in a cool dark cellar then bringing them in to the warmth and light to flower?
There are three main grouping of flowering plants in relation to day length and their growth and flowering. Assuming that the plant is sufficiently mature and ready to flower, the day length becomes crucial for many of our favourite garden flowers.
Short day plants, Chrysanthemum, for example, react to the day length being shorter than a specified time; or put another way, when the hours of darkness are longer than the hours of daylight. So these plants tend to flower later in the season, during late summer and autumn.
Long day plants, such as Gypsophilla, tend to be spring and summer flowering plant; they respond to the day length being longer than a specified amount of time. However, day neutral plants, for example, Viburnum, are unaffected by the length of daylight hours and will flower when they are mature enough to do so.
So this is why the Autumn Equinox, as illuminated by the Harvest Moon, is a crucial turning point in the gardening year.
The cover illustration for our newest eBook “In Your Autumn Garden with Plews Garden Design” shows Demeter, who was the Greek goddess of the harvest and fertility and one of the aspects of the Triple Goddess, or Earth Mother, Gaia. An appropriate subject for a book about crops and harvest and food in your garden and allotment, we thought.