What is Dormancy in Plants & Trees?

What is Dormancy in Plants & Trees?

If the cold weather makes you want to curl up in bed and hibernate until spring, you’re not the only one. Many of your plants and trees follow that very strategy to get through winter. It’s known as dormancy, and it's a natural process that helps them survive the colder months. 

But what exactly is dormancy in plants, and what kind of care does a dormant plant need? 

If you’re wondering which of your plants will go dormant and what they need over the winter, we’re digging into all the dormancy details, including what happens to plants when they enter this state and how to care for them until new growth begins.

What Is a Dormant Plant?

Think of dormancy as the plant version of hibernation. It’s a survival adaptation that allows plants and trees to survive poor growing conditions. It’s essentially a state of arrested development, in which growth slows and metabolism decreases. Think of your lawn going brown and dry over the winter or in extreme summer temperatures—that’s dormancy at work.

In trees, dropped leaves and slowed growth are a sign of dormancy. However, their roots will not go dormant during the colder months, since they’re protected underground.

That said, many plants enter dormancy to survive cold weather. The process can also be induced by:

• Drought
• Disease 
• Physical damage

Dormancy allows the plant to conserve energy by dying back partially or all the way to the roots. By slowing or stopping growth and metabolism, dormancy helps plants outlast periods of stress. Dormancy also allows plants to adapt to changing environmental conditions or avoid damage from extreme weather, diseases, or pests.

Dormancy in Perennial vs. Annual Plants

If you’ve spent much time wandering your local nursery, you’ve probably discovered that gardeners group plants into two large categories: annuals and perennials. Dormancy is one of the biggest differences between these two types of plants.

Annual Plants

These plants complete their life cycle in one year and then die. They don’t usually have a natural ability to go into dormancy. Instead, they simply grow and reproduce quickly over a single season. However, some annuals are actually perennials in their native regions, and you can try bringing these plants inside for the winter. 

Here are some tips for overwintering longer-lived annuals:

• Pick durable plant varieties – Popular annuals that can last for several seasons include fuchsias, begonias, geraniums, impatiens, and nasturtiums, and tropical bulbs like canna lilies and dahlias. 

• Prune your annuals – Some annuals, including fuchsias, can be put into dormancy at the end of the growing season by trimming them back and storing them in a dark, cool (but not freezing) location for the winter months.

• Keep the water flowing – Water your plants occasionally through the dormancy period—once a month should be sufficient.

• Bring your plants inside – Begonias, coleus, nasturtiums and many others can simply be brought inside for the winter to keep growing .

That said, different annuals have different needs, so it’s best to research how to overwinter each species to ensure your plant baby is well taken care of. 

Perennial Plants

Perennials are plants that live for multiple years. This means that in temperate and continental climates (climates with four seasons), they have to be able to survive drastic changes in light, temperature, and rainfall. 

Perennials have a period of dormancy because their life cycle is long enough that they can afford to wait out unfavorable conditions. For example, deciduous trees lose their leaves and enter dormancy when temperatures are too cold for growth. This allows the tree to conserve energy and avoid damage from the cold weather.

Most perennials need minimal help to survive the winter, but here are some quick tips to keep your hardy plants happy in the cold:

• Trim foliage – Plants with leaves that have become brown or black can be trimmed back to tidy up your garden. Don’t cut growth back too early—while the plant is green, it’s still storing energy in the roots to last through the winter. 

• Cut back – Cutting dead growth back usually isn’t necessary unless the leaves and stems are moldy or diseased.

• Avoid watering – Don’t water your perennials in winter, as soil that’s too wet can lead to root rot.

What Causes Dormancy?

What triggers a plant to enter dormancy varies depending on the species. But in general, plants begin to prepare for dormancy in late summer or early autumn, when days become shorter and nights become longer. 

This signals to the plant that winter is coming and that it needs to start conserving energy.

Other conditions that can trigger dormancy include:

• A long period of cool temperatures
• A period of reduced light
• Changes in the angle of the sun
• Changes in moisture levels or other environmental factors

What Happens During Dormancy?

Dormancy isn’t a total resting state. The plant is still producing and consuming some energy in the root system and stems. But when a plant enters dormancy, various cellular changes happen that help the plant survive with less light and less water. These changes include:

• Reduction in the rate of metabolism (aka, using less energy)
• Reduction in water loss
• Decrease in the production of enzymes

Does My Plant Need a Dormant Period? 

For most plants, a rest period helps to achieve the best growth and flowering. This can be a problem for houseplants that never feel cooler temperatures and therefore never have a break from their growth phase. When it’s winter outside, your houseplants will appreciate a rest too. 

To help your houseplants go dormant:

• Move plants to a room that stays cool (but not freezing) in the winter
• Keep plants away from heat sources where temperatures can fluctuate rapidly
• Position plants away from windows
• Water infrequently—once a month should be enough
• Don’t feed dormant plants 

Dormancy for flowering houseplants

Some flowering favorites need a dormant period even more than your other houseplants. Without it, you’re unlikely to get an annual bloom. These plants include:

• Christmas cactus
• Poinsettias
• Amaryllis

These plants should be moved to a cool, dimly lit room in your house for a part of each year. Reduce watering to once a month. After the plant has rested for a month or two, move it back into a warmer, sunnier room. Soon you should be rewarded with a beautiful display of blooms!

Is My Plant Dormant…or Dying?

Drooping, yellowing, or even dropping leaves don’t necessarily mean your plant is dying. As we know from deciduous trees, losing leaves can just mean a plant has gone completely dormant. 

Here are three ways to tell what state your plant is in:

• Snap test – Try breaking a small twig or stem. If it snaps easily and seems dry and brittle, the plant may be dying. If the stems are green and flexible, the plant is most likely dormant.

• Scratch test – For plants with gray or brown bark, you can scratch the bark with a fingernail to check for signs of life. Moist green or white “skin” underneath the outer bark is a sure sign the plant is simply at rest.

• Root test – Check around the plant’s roots. Are the roots smelly, black, or slimy? That’s a sign of a dead or dying plant. A dormant plant’s roots should be flexible, white, and firm.

How to Care for a Dormant Plant

When a plant is dormant, it doesn't need much care from you. In fact, over-watering and over-fertilizing can be harmful to plants during dormancy. 

Here are a few ways to look out for your plants while they rest:

• Mulching – In regions where nighttime temperatures drop below freezing regularly, a layer of straw, bark, or other mulch can protect roots from extreme temperature swings. But in warmer regions where freezing is less frequent, mulching can actually keep your plant from becoming dormant when it should be. Look up your zone and mulch appropriately for your region.

• Pruning – One thing you can do to encourage vigorous spring growth is pruning. Pruning can—and should—be done during the dormant season. Cut back any dead growth, and reshape plants that have gotten leggy or too large. (But remember to check the inside of stems and branches for green before assuming they’re dead.)

• Watch for disease and pests – Dormant plants can still develop problems like mold, fungus, and pests. Check regularly for signs like white fluff, fuzz, or cobwebby growths on stems and around roots.

How to Care for Your Waking Plant

As the days grow longer and warmer, you should see signs of new growth. The first sign is often a change in color, as the leaves or stems start to turn green. Then, watch for new leaves, shoots, or buds starting to form.  

Your plants will naturally come out of dormancy when conditions are right. But you can help your dormant friends perk up quickly with:

• A half-strength dose of fertilizer to help encourage new growth
• More frequent watering 
• A warm, sunny location for outdoor container-grown plants
• A sunnier location for houseplants (but avoid direct sun)

Nurture Your Plants All Year Round With Plants Express 

No matter the time of year, you can give your plants the TLC they need to thrive. During their dormant phase, be sure not to overwater or feed them. But when the growing season rolls around, be ready with plant food, water, and a sunny location for container-grown plants. It’s also a good time to size up pots and top up with fresh potting soil. 

In every season, Plants Express is here to help your plants and trees flourish.  

Whether you’re a seasoned landscaper or a new plant parent, we have the know-how and supplies you need to take your garden to the next level. With over 2,400 varieties of plants and trees grown right here in California, gardening with Plants Express is always a blooming success. 

 

Sources: 

Encyclopedia of Ecology. Dormancy. https://doi.org/10.1016/B978-008045405-4.00503-6 

Gardening Info Zone. Houseplants: The dormant period. https://www.gardeninginfozone.com/houseplants-the-dormant-period 

Gardening Know How. Mulching plants in winter. https://www.gardeningknowhow.com/garden-how-to/mulch/mulching-plants-in-winter.htm 

Gardening Know How. When do plants wake up. https://www.gardeningknowhow.com/garden-how-to/info/when-do-plants-wake-up.htm 

Iowa State University Horticulture and Home Pest News. Annual flowers for indoor use.

https://hortnews.extension.iastate.edu/1996/11-8-1996/anflower.html 

Michigan State University Extension. Winter dormancy and chilling in woody plants. https://www.canr.msu.edu/news/winter_dormancy_and_chilling_in_woody_plants 

University of New Hampshire. Dormancy: A key to winter survival. https://extension.unh.edu/blog/2018/12/dormancy-key-winter-survival 

Science. Dormancy of Trees in Winter. https://www.science.org/doi/10.1126/science.171.3966.29?cookieSet=1