Weather Changes in Early Winter
Author: The ilikeseeds team
What Happens to Plants During the Winter Months? ☃️
After spending hard worked hours outside getting your garden and yard ready for the winter, you can finally sit back, relax, and let Mother Nature take over for the winter. However, you may have wondered during the labour of preparing your yard why you actually need to go through the winterisation process.
Cool temperatures in Early Winter trigger the plant to reduce growth and store energy. As temperatures approach freezing, growth stops and the plant (if perennial) becomes dormant. Plants are better able to withstand cold temperatures when dormant. A sudden cold snap in late fall before the plant has had a chance to harden off can do more harm than sustained cold temperatures in mid-winter.
Many plants require a chilling period of a certain number of days before growth resumes in spring. Plants native to areas further south with a shorter chilling requirement may resume growth during a warm period in winter and then be damaged when cold weather returns. Plants native to the area will generally not break dormancy. Wide temperature fluctuations can be hard on plants, particularly in winter. Warm days followed by freezing nights can cause bark injury on trees with thin, smooth bark. Alternate freezing and thawing of soil can result in heaving of shallow-rooted plants. Temperature (along with day length in some cases) can also trigger flowering in some plants, as well as affect how long flowers last
If the seeds are from an introduced species that originated from a colder climate, they will be genetically programmed to survive winter. Garden species from the northern hemisphere evolved to survive these harsh conditions. They're still adapted to the conditions in which they evolved. They just haven't been in Australia long enough to adapt to local conditions. So, seeds lie dormant, metabolising at low levels, waiting for spring.
It’s only when a seed has been exposed to low temperatures for long enough, a process known as cold stratification, that plant hormones trigger the end of dormancy. At this time, if environmental conditions are favourable, say there's enough water around, the seed can then germinate, again a process governed by plant hormones.
Drops in temperature slows down a plant's metabolism largely because the enzymes that drive these biochemical reactions don't work so well in the cold. Photosynthesis slows, respiration slows, growth stops.
A classic example is your backyard lawn, which stops growing over winter if the temperature is low for long enough.
Being exposed to less sunlight also plays a role in grass growth this time of year due to the lower angle of the winter sun and shorter winter days. That means less photosynthesis, which in turn means fewer sugars to metabolise. If you can't make the energy, you might as well close up shop. You're not making enough for growth. The result? Gardeners don't have to mow the lawn for a while.
Plants use winter dormancy to keep their houses in order. For instance, proteins are broken down and re-made and cell membranes are maintained.
Plant hormones (first auxin, then ethylene) then trigger the leaves, which are now largely stripped of nutrients, to fall off the tree.
Buds can also lie dormant over winter, often covered in scales, until the plant been exposed to low temperatures for long enough. Cherry trees, for instance, are genetically programmed to undergo a winter before buds open in spring. So, even if we have an unusually warm winter, buds won't burst to life until the tree has been chilled.
But how do plants 'know' or register when they've been exposed to enough cold weather?
Plants have a temperature memory. They measure the product of time and temperature and can work out how cold it's been and for how long. They do this, by keeping track of the interactions between certain proteins, a sign that it's time to activate a key gene to break dormancy. Some people say this sequence of events is evidence that plants do maths to calculate the product of time and temperature. Others dispute whether plants are computing anything at all.
Either way, there's clearly more going on in your winter garden than you might think — doing the maths or not!.
Trees and Plants. All deciduous trees and plants (those that lose their leaves in the Autumn, will go dormant to conserve energy. These types of plants use the spring and summer months to store nutrients to prepare for colder weather, while evergreen trees will still conduct photosynthesis, but at a much slower rate during those cold Rhode Island winter months.
Water scarcity. Colder temperatures mean frozen water, and that is an issue for plants. Frozen water makes it difficult to draw water up into trunks or stems. However, a blanket of snow will insulate the ground, reducing freezes and allowing water to stay in liquid form. Plants that are dormant for the winter need less water. Deciduous trees will lose water rapidly if they don’t shed their leaves in time, while conifers have a thick, waxy coat on their needles to prevent water loss.
Plant Shapes. Did you know that the shape of a tree or plant will either help or hinder it during the winter months? Therefore, landscape contractors will always be sure to trim or cut back the stems and leaves of any annual plant that goes dormant during the winter. Not winterizing your garden could lead to irreversible damage; many plants have inflexible stems that snow can easily snap. Conifer trees, however, were meant for harsh winters. Their branches point downwards to shrug off any accumulating snowfall.
The ilikeseeds Team.