Seasonality and Dormancy in Succulents

Many plants are seasonal. For example, if you are from the East Coast of the US, you are familiar with the brilliant displays of trees having their leaves turn vibrant shades of yellow, orange, and red in the fall. That color change is a signal that the trees are preparing to go dormant. This vibrant display of colors is a hallmark of deciduous forests in temperate regions and is an adaptive strategy for nutrient recycling and tree survival during the dormant season.

Succulents also change with the seasons. Because different succulents evolved in different habitats, the exact seasonal response will be different. Those differences are tied to the environments where different succulents evolved and their seasonal rainfall patterns. Many succulents have adapted to environments where rain is not only scarce but also highly seasonal. For example, in some habitats, it may rain primarily during winter and be dry for the rest of the year. In others, the rain may come during summer with dry winters, or rainfall might peak in spring and autumn. During periods of drought, plants may enter dormancy as a survival strategy. This dormancy is programmed into the DNA of the plants. When these plants are cultivated, they tend to go dormant during the seasons when the environment where they evolved is typically dry.

What triggers plants to go dormant and what triggers them to come out of dormancy? Photoperiod (day length), temperature, and availability of water are sensed by plants and play a role in regulating dormant periods. Understanding these cues is key to successfully cultivating succulents.

Case Study: Aeonium

Let’s take Aeonium as an example. These plants are native to the Canary Islands.

Rainfall Patterns in the Canary Islands:

Dark green indicates the wettest months with the highest rainfall. Lighter shades of green represent decreasing rainfall levels. As seen in this graph, the Canary Islands are dry during the summer months (May, June, July) and wet during autumn, winter, and spring. In cultivation, the growing periods of Aeonium reflect their adaptation to the Canary Islands' growing seasons. Aeonium begin growing in the fall, grow all winter, and flower in late winter or early spring. As summer approaches, they go dormant, and their rosettes curl up into tight, space-age-looking disks as a survival mechanism to conserve water and energy.

Aeonium in full growth in California in January:

Aeonium dormant at the end of summer with the rosette closed up to conserve water:

Just as Aeonium are adapted to the rainfall patterns of the Canary Islands, succulents from other regions have evolved to thrive in their unique habitats. These adaptations dictate their seasonal growth cycles, dormancy periods, and care requirements in cultivation.

Rainfall Patterns and Native Succulents.

Succulents have adapted to thrive in some of the most diverse and challenging environments on Earth. From fog-laden deserts to arid mountain ranges, these plants have evolved remarkable strategies to survive and grow in response to their local rainfall patterns. Understanding the unique habitats where succulents originate provides valuable insights into their care, helping us mimic their natural conditions in cultivation.

Little Karoo (Oudtshoorn, South Africa)

The Little Karoo experiences a semi-arid climate with rainfall distributed throughout the year, peaking slightly in spring and autumn. This irregular pattern supports a variety of succulents adapted to dry conditions and intermittent moisture.

Native Succulents:

• Tylecodon species

• Crassula species

• Gasteria species

• Haworthia species

• Euphorbia species (e.g., Euphorbia mauritanica)

Great Karoo (Beaufort West, South Africa)

The Great Karoo has an arid climate with low annual rainfall, primarily occurring in late summer and early autumn. Succulents here are highly drought-tolerant and often have deep root systems or thick leaves to store water.

Native Succulents:

• Aloe dichotoma 

• Euphorbia stellispina

• Mesembryanthemum species

• Pelargonium species

• Pachypodium succulentum

Atacama Desert (Antofagasta, Chile)

The Atacama Desert is one of the driest places on Earth, with negligible rainfall throughout the year. Succulents here often rely on fog (known locally as camanchaca) for moisture, making them exceptionally adapted to arid conditions.

Native Succulents:

• Copiapoa species (e.g., Copiapoa cinerea)

• Eulychnia species (e.g., Eulychnia saint-pieana)

• Neoporteria species

• Tillandsia landbeckii (epiphytic succulent adapted to fog capture)

Baja California (Ensenada, Mexico)

Baja California features a Mediterranean climate with most rainfall occurring during the winter months. This supports a diverse array of succulents, many of which are endemic to the region.

Native Succulents:

• Dudleya species (e.g., Dudleya brittonii, Dudleya pulverulenta)

• Ferocactus species

• Mammillaria species

• Agave shawii

• Pachycereus pringlei (Card\u00f3n)

Namaqualand (South Africa)

Namaqualand experiences winter rainfall and a desert climate, famous for its spring wildflower displays. Succulents here thrive in nutrient-poor soils and extreme heat.

Native Succulents:

• Lithops 

• Fenestraria rhopalophylla 

• Conophytum 

• Tylecodon 

• Aloe variegata 

Sonoran Desert (Mexico and Southwestern USA)

The Sonoran Desert has two rainy seasons: summer monsoons and winter rains. This dual rainfall pattern supports diverse succulents with adaptations to heat and occasional frost.

Native Succulents:

• Carnegiea gigantea (Saguaro Cactus)

• Fouquieria splendens (Ocotillo)

• Opuntia 

• Echinocereus 

Chihuahuan Desert (Mexico and Southwestern USA)

The Chihuahuan Desert has summer rainfall and cooler winters, supporting a mix of succulents and hardy desert plants.

Native Succulents:

• Agave 

• Echinocactus 

• Dasylirion 

• Mammillaria 

• Thelocactus 

Seasonality in Succulents:

In cultivation, the growing cycles of different succulents will reflect the environment and rainfall patterns of the habitats where they evolved. Here’s a categorization of succulents with seasonal growth patterns:

Importance of Understanding Seasonality

Knowing the seasonality of succulents is crucial because dormant plants have reduced defenses against pathogens and are more sensitive to rot. For example, cacti, Euphorbia, Stapelia-related plants, and many other winter-dormant succulents will rot if watered during winter dormancy. On the other hand, winter-growing succulents like Aeonium are active during the cooler months and require careful watering during their growth phase to avoid desiccation.

When succulents are actively growing, they can process water, nutrients, and sunlight efficiently. However, during dormancy, metabolic processes slow down significantly, making the plants unable to handle excess water. Providing the right amount of water at the right time is the cornerstone of successful cultivation.

Haworthia tend to grow all year but will go dormant during the hottest part of summer and coldest part of winter. This dormancy is triggered not by photoperiod but by temperature. Excessive heat or excessive cold will trigger dormancy. Watering Haworthia when they are dormant can lead to rot. 

Conclusion

Understanding the seasonal growth habits of succulents is an essential aspect of their care. By recognizing whether a succulent is a summer grower, winter grower, or grows in spring and fall, you can tailor your watering, lighting, and fertilization schedules to match their natural cycles. This not only ensures the health and longevity of the plants but also prevents common problems such as rot and pest infestations during dormancy.

Whether you’re cultivating Aeonium, cacti, or other succulents, aligning your care routine with their natural rhythms allows these remarkable plants to thrive, bringing beauty and diversity to your collection year-round.

 Mesembs in habitat in South Africa winter 2006.