It’s fall, which means nature is getting ready to sleep. The leaves are falling from the trees, birds are flying south. But the lilacs still in bloom? Chestnut trees in bloom? Are the buds of the apple trees sprouting, the thorn bushes blooming, the verbena blinking blue on the lawn? Is it autumn-flowering?
Plants that do not bloom in time are always surprising and raise many questions: why does it happen, what are the consequences, how to deal with it? And sometimes it is frightening: everything that remains unexplained leads to anxiety and superstition.
But, in fact, scientists have been studying the causes and consequences of this strange phenomenon for years, and not without success. Let’s find out about it too.
CHARACTERISTICS AND CAUSES OF UNTIMELY FLOWERING OF FRUIT CROPS
The plant blooms in autumn, sometimes in winter, late spring, or even late summer, which is common in temperate climatic zones. In some years it is more abundant and in other years less. However, it can theoretically reappear two to four times per growing season.
Also, untimely flowering is more often seen in crops of the Rosaceae family. It includes the familiar drupes, plums, rutabagas, cherries, thick plums. Seed plants of apples, pears, rowan trees, willows, hawthorn. One-time fruiting of some berry crops, blackberries, strawberries, and raspberries.
But it also occurs on nut plants and ornamentals, on many species of annuals and biennial herbaceous plants.
What are the causes of this phenomenon? Many factors coexist:
- sudden changes between dry and subsequently wet, warm weather.
- Exposure of plants to gases.
- The intensity of direct solar insolation.
- A downward spike in temperature followed by sustained warm weather.
- Exposure to toxic substances.
- Severe damage by insects, animals, or mechanical contusions.
However, it has been noted that fall flowering of trees and shrubs does not occur in cloudy autumn days or later than the initial stage of organic bud dormancy.
Another reason is diversity. If the characteristics of cultivars include a short vegetative period (northern cultivars have this characteristic), the plants start flowering in autumn due to a long warm period, especially if it has been cold before.
This is often the case with honeysuckle, which is native to the north. By the end of August, the culture finishes the flower bud formation period and, if conditions permit, it begins to bloom. In addition, the warmer the weather, the more strongly it flowers.
THE NATURE AND CONSEQUENCES OF AUTUMN FLOWERING
The flower buds of fruit plants are formed for almost a year. Depending on the crop and environmental conditions, it is about 300 days, covering summer, autumn, winter, and early spring.
However, in some cases, the combination of nutrient overload and high temperatures during flower formation, this process is accelerated many times and may take only about two months (60 days).
The biological significance of this phenomenon is still unknown. What is clear, however, is that the consequence of autumn flowering is a partial loss of the next year’s harvest.
Simply put, what should flower in spring blooms before winter, and new flower buds do not have time to form during the winter period because conditions are not suitable.
In addition, during flowering, plants deplete their reserves of photosynthetic products, which reduces their winter hardiness and frost resistance. Therefore, it is not surprising that they are damaged by frost during the harsh winter months.
WHAT CAN I DO WITH CUT FLOWERS THAT DO NOT BLOOM IN TIME?
Given that perennials consume energy during flowering, even if only a little, then buds that are about to open should be removed as soon as they are found. Especially if they are already present on young plants.
HOW CAN I PREVENT MY GARDEN CULTURE FROM FLOWERING IN AUTUMN?
Accelerated development of flower buds occurs mainly during dry summer months (stress inhibits the growth process of shoots and accelerates the development of bud tissue), combined with subsequent sharp moisture (heavy precipitation or watering) at the right temperature regime.
Therefore, timely and comprehensive care of the garden during the summer and early autumn – regular watering and pest control can prevent autumn flowering. There is also the selection of varieties suitable for the climatic zone, whose development period corresponds to the conditions of the region.
MORE INFORMATION ABOUT LATE FLOWERING
Late spring or summer blooming
Sometimes flowers start to bloom later than usual in the spring, with a delay of a few days to a few weeks. Sometimes you can also see the flowers on the trees in mid and late summer. What is the reason for this?
Trees and shrubs do not bloom during the unusually late spring, but only a few flowers open. This is due to delayed development of individual flower buds caused by lack of nutrients, autumn cold, frosty shoots, or any other stress.
Late summer flowering is mostly seen in the shoots of the current year. It occurs in early flowering varieties.
It is caused by the early warm spring and the following sunny, hot summer: trees and shrubs enter the development stage early, grow rapidly, and manage to enter the stage of forming flower buds even before autumn, which, under favorable conditions, leads to untimely flowering.
Winter flowering
In the winter months of January and February, premature flowering can be seen only in the south. In the Caucasus and Crimea, during these months, the temperature often jumps to very high levels of 62-75°F (17-24°C) and remains for quite a long time, awakening the buds to flowering.
During such periods, black apricots, almonds, and cherry plums manage to bloom. But, unfortunately, the returning cold does not allow them to bear fruit.
Annuals and biennials
What about herbaceous plants? Untimely flowering is also common for them. Annuals usually germinate in the warm fall by awakening dormant buds. However, perennials will flower after a brief drop in temperature and need time to vaporize.
Therefore, the process of secondary or repeated flowering is not a unique or unexplained phenomenon. Yes, it is surprising and even somewhat alarming each time.
But considering that usually, no more than 1% of the buds bloom on the wrong date, it does not cause particular damage to the yield or the decorative effect of the plant.
So you need not be afraid. If you can, you should help prepare your garden for winter.
