Plants go through different stages in their life cycle. One of these important stages is known as the resting stage. This refers to a period when plants slow down their growth and go into a state of dormancy. The resting stage allows plants to conserve energy and resources to survive stressful environmental conditions like winter cold or summer drought.
When does the resting stage occur?
The resting stage can occur at different times depending on the plant species and variety. Some common examples include:
- Winter dormancy – Many perennial plants native to temperate climates will go dormant in winter to survive the cold temperatures and frost. Deciduous trees shed their leaves and woody plants die back to the ground.
- Summer dormancy – In hot, dry climates some plants will go dormant in summer to survive drought conditions.Examples include tuberous begonias and certain bulb plants.
- Seed dormancy – Mature seeds from many plant species have built-in dormancy mechanisms that prevent immediate germination. This ensures seeds will germinate at the optimal time.
- Bud dormancy – Woody plants enter bud dormancy in fall and winter to protect tender growth buds from cold damage. Bud break occurs when dormancy ends.
Dormancy onset is often triggered by environmental cues like changing day length, temperatures, moisture levels, or chemical signals in the plant.
What happens during the resting stage?
During the resting stage plants undergo many physiological and biochemical changes to prepare for survival. Some of the key things that happen include:
- Growth slows down – Visible growth like leaves and shoots stops and metabolic activity is reduced.
- Leaves may be dropped – Deciduous plants shed their leaves to reduce water loss and conserve energy.
- Flowers and fruits are shed – Reproductive parts are discarded to direct resources away from reproduction.
- Buds become dormant – Growth buds become inactive to protect them from cold damage.
- Food reserves accumulate – Starch and other compounds are stored to supply energy for future growth.
- Cell structure changes – Changes in cell wall thickness, water content and protoplasm viscosity occur.
- Resistance increases – Chilling and drought resistance improves to withstand harsh conditions.
These changes allow the plant to essentially “shut down” non-essential functions and divert resources to structural integrity and storage.
What triggers the end of resting stage?
The resting stage ends when conditions become favorable again for resumed growth and reproduction. The triggers ending dormancy include:
- Warming temperatures – Increasing temperature and daylight stimulate growth hormones.
- Changes in day length – Longer days initiate bud break and flowering.
- Moisture – Water triggers growth in summer dormant plants.
- Chilling exposure – Exposure to weeks or months of cold is needed to break winter dormancy.
- Fire or animal damage – Physical damage to buds and stems stimulates growth.
- Chemical signals – Compounds like ethylene, cytokinins and gibberellic acid induce activity.
Not all parts of the plant break dormancy at the same time, allowing gradual, staggered growth. Proper timing is critical so active growth isn’t initiated too early or late in the season.
What are some examples of plants with resting stages?
Many plant species across diverse climates undergo dormancy periods when conditions are unfavorable. Here are some common examples:
Trees
- Oak trees – Oaks enter winter dormancy and shed leaves. Chemical changes in buds must occur before growth resumes in spring.
- Maple trees – Maples enter bud dormancy in fall and winter. Stored starch provides energy for spring growth.
- Apple trees – Apples trees accumulate chilling hours in winter to ensure proper blooming and fruit set later.
Shrubs
- Roses – Rose bushes become dormant in colder zones in winter, then put out new growth when temperatures warm.
- Forsythia – Forsythia shrubs flower intensely in spring following winter dormancy.
- Hydrangea – Growth stops in fall and winter. Bigleaf hydrangeas flower in early summer on old wood.
Bulbs & Tubers
- Tulips – Tulip bulbs require 12-15 weeks of temperatures below 45°F to flower properly.
- Dahlias – The tubers become dormant in winter and sprout new growth when re-planted in spring after frost danger passes.
- Caladiums – Summer dormant caladium tubers are stored dry and cool over winter.
Succulents & Cacti
- Burro’s Tail – This succulent sheds leaves and goes semi-dormant in summer heat. Water sparingly.
- Christmas Cactus – Blooming is induced in fall/winter after providing cooler night temperatures.
- Snake Plant – Overwintering indoors, snake plants grow slowly. Rapid spring growth occurs after moving outdoors.
Conclusion
The resting stage is a period of reduced growth and metabolic activity that allows plants to conserve resources. It is an important adaptation enabling survival through unfavorable conditions like cold winters or hot, dry summers. Dormancy transitions are triggered by environmental factors and chemical signals. Knowing the specific dormancy requirements of plants can help provide proper care and ensure healthy growth cycles.