by Matt Gibson
Dormancy is your garden’s practice of continuing to thrive during cold weather conditions by entering a state of inactivity or minimal activity, saving its energy for a time when it can be better put to use. Even though it doesn’t look as though they’re thriving on a surface level, your perennial plants are basically hibernating and conserving energy until more suitable weather conditions come back around, which is smart, and crucial to their survival and capability to regrow the following year.
Plants don’t just go into a dormant-like state during cold weather conditions, but can also enter dormancy during other times of stress, such as extreme heat or drought. During such adverse weather conditions, many plants, especially trees, enter a temporary dormancy, shedding their leaves early to conserve the low levels of moisture that they have on hand in order to survive until conditions improve.
Why do plants go dormant in the winter?
During dormancy, plants go inactive and conserve their energy until better weather conditions for plants present themselves. When this occurs, your dormant plants wake up and return to business as usual. This happens naturally as seasons and weather change. Plants are triggered into dormancy because of cold weather, less hours of sunlight exposure, shorter days, and expectations developed from previous winters and seasonal cycles.
During the winter, your dormant plants aren’t actually dead, they just suspend their growth and expansion, thus appearing dead to those that don’t understand the process. Even as the plant’s outermost leaves and ornamental foliage may die and need to be trimmed down, sometimes down to barely anything, the roots and core of the plant are still very much alive, just waiting for weather that is more suited for their growth and expansion.
What happens to plants during winter?
The period of dormancy, where plants discontinue growth, is brought upon by the dropping temperatures and shorter day lengths that come with the winter season. For plants, dormancy is more than just suspending growth. It’s partially about surviving during harsh weather conditions, and partially about conserving nutrients.
Though growth stops, photosynthesis slows, and respiration slows, that doesn’t mean that your plants are not hard at work. The work they do during dormancy is vital to their survival, and the way they use nutrients to thrive during the upcoming growing seasons.
During dormancy, your plants break down and remake proteins to use for extra growth in the spring. Plants are also hard at work maintaining and strengthening cell membranes, which will come in handy when they begin to expand and multiply when the weather changes.
Do all plants go dormant in the winter?
Nearly all plants go dormant during the winter, whether they are outdoors in the garden or indoor houseplants. The rest period is crucial to the plant’s survival and their ability to regrow each year.
Annual plants, on the other hand, don’t go dormant during the winter, for they don’t have the mechanism for going dormant and returning in the spring. Annuals are only equipped with the life-cycle of a single growing season.
Which plants go dormant in winter?
Nearly all plants, outdoor and indoor alike, go dormant in the winter. This applies to flowers, vegetables, groundcovers, vines, bushes, shrubs, and trees. Even if you make a cold frame or lay out blankets to protect your plants in the winter, and even if you bring them indoors to store them during the cold season, they will eventually go into dormancy. The only plants that don’t go dormant during the winter are annuals, which are only capable of surviving for a single growing season, and must be replanted each year for continual enjoyment.
How do you care for dormant plants?
There are many different types of plants that go dormant during the winter, and each type needs a different specific form of care. The following instructions apply to certain tropical tender plants and how to care for them over the winter:
For begonias, dahlias, caladiums, cannas, callas, ginger, sweet potato vines and colocasias, store the dormant tubers, bulbs, and corms in a cool, dark place during the winter and reintroduce them into your garden in the spring when the weather becomes warm and the last threat of frost has passed.
For dwarf cannas, brugmansias, and banana plants, bring indoors and keep the dormant plants in a cool, dark location.
For palms, croton, bamboo, jasmine, cordyline, phormium, allamanda, bougainvillea, hibiscus and citrus, bring them indoors and overwinter them as houseplants. Store in a warm, sunny location, such as a heated greenhouse or sunroom.
For geraniums, coleus, and plectranthus, take and pot up some root cuttings so that you will have some fresh new plants in the spring.
For houseplants, the general rule is to stop feeding them but give them access to a sunny location throughout the winter, resuming regular feeding mid-spring. For a more detailed list of ways to keep houseplants happy during the winter, click here!
How do you tell if a plant is dormant or dead?
There are two different types of dormancy. Predictive dormancy, which is usually triggered by a drop in temperature, is when a plant assumes that winter is coming and starts to shut down in advance of its arrival. Consequential dormancy is when a plant goes into dormancy after adverse weather conditions arise.
Plants go into dormancy for good reason, and a species that has dormancy needs cannot be tricked to stay out of dormancy for prolonged periods without negative consequences. If you bring a temperate climate plant indoors, you can get it to grow for about two years straight, at which point it will go into dormancy no matter what environment it is provided with, and that dormancy will be prolonged until the plant has fully prepared itself for the upcoming seasons.
Deciduous plants will shed their leaves and evergreens will stop all new growth. Both indoor and outdoor plants will go into dormancy when they are stressed. If a plant is super dry, it may shed its leaves in an attempt to conserve what little water remains in its system. Many times, dormant plants are discarded because they are believed to be dead, when they are really just waiting for environmental conditions to improve before continuing growth. Whether it is due to stress or winter weather conditions, plants will go dormant as a defense mechanism to keep themselves alive. So, how do you know if a plant is dormant, or really dead?
One method is the snap-scratch test. Grab a twig from the plant, shrub, or tree in question and bend it sharply back upon itself. A dead limb will snap easily, while a living limb will simply bend, showing moist, living wood within. Alternatively, use a knife or fingernail to scratch the bark of a young twig. A living limb will reveal green under the bark and will be slightly damp. A dead limb will reveal brown dry material.
Another way to check whether a plant is dead or just dormant, is to inspect its root system. If the roots are rotten or shriveled, the plant is most likely dead. If the roots are light and supple, then you are in luck, your plant is just in a state of dormancy, and will soon return to growing once more. Sometimes, the root test is challenging to discern, as some roots are dead and shriveled, while others look unaffected. If this is the case, it’s important to check the primary root first and foremost. If the primary root is healthy, then the plant is probably just dormant. In this case, you probably will want to cut off the shriveled or diseased roots entirely, leaving just the healthy roots intact before replanting the plant back into its home.
What triggers dormancy in a plant?
There are several weather changes that can trigger dormancy in a plant. The most common weather change that triggers dormancy is a drop in temperature. Shortened daylight hours can also be a signal to a plant that the time for dormancy is upon them.
Want to learn more about dormant plants?
ABC Science covers What Happens to Plants in Winter?
Gardening Know How covers Understanding Plant Dormancy
Gardenista covers 11 Ways to Keep Plants Happy in Winter
Jobe’s covers When Plants Go Dormant
Lifehacker covers How to Tell if Plant is Dead or Dormant