In my last column, I posted pictures of garden plants that provide an attractive display during the winter months. Two of these plants, tree aloe (Aloe arborescens) and black rose aeonium (Aenium arborescens “Zwartkop”), are examples of a remarkable group of succulents called “winter growers.”
Today’s column focuses on winter-growing succulents and includes photos of additional examples of this group.
Let’s start with an overview of plant dormancy, the process by which plants function. Other processes include photosynthesis, respiration, transpiration, and seed germination.
Dormancy is a period during which plant growth ceases. It is essentially a strategy that allows many plant species to survive during periods that are not suitable for growth. I have.
Plants enter dormancy when their biological clocks prepare for freezing temperatures or water shortages, or when unexpected environmental conditions call for a protective response.
The normal dormancy period can be altered by chemical treatments, which can break dormancy in some woody plants. And, more importantly for home gardeners, it can be changed by growing indoors (limiting temperature extremes and maintaining adequate moisture).
Gardeners in temperate climate areas such as the Monterey Bay area may observe reduced dormancy (some shrubs may be slow to shed their leaves during winter).
Dormancy is evident in many plants, especially deciduous trees and shrubs, herbaceous annuals and perennials, and bulbous plants. However, for succulents, dormancy is less obvious, but it is still an important process for gardeners to be aware of.
The succulent genus has two categories of dormancy: summer dormancy (those that grow in winter) and winter dormancy (those that grow in summer). As with other categories of plants, these are guides, not sharp distinctions, and some species may serve slightly different functions.
Summer dormancy (winter growers) is usually dormant from May to August when the months are warmer. Their growth occurs mainly in autumn, winter and spring, slowing down during the coldest months of winter (January and February). Many of these plants are native to South Africa. Popular genera include Aeonium, Aloe, Bulvin, Cotyledon, Crassula, Gasteria, Haemanthus, Haworthia, Kalanchoe, Pelargonium, Portulacaria and Sansevieria.
Winter dormant (summer growers) are usually northern hemisphere adapted plants. They are dormant from November to February. They grow during the summer months of spring, summer and fall. They may rest during the hottest months of summer and resume growth in September and October. Plants in this category include some South African natives. Adenia, Euphorbia, Phokia, Lithops, etc. Some from Mexico, Central America, or South America: Agave, Brucella, Echeveria, Ipomoea, Pediranthus, Plumeria, Siningia, Tillandsia.
A gardener’s most important consideration related to dormancy is irrigation. Plants require moisture during the growing season and little or no moisture during the dormant phase. Watering should be done when the soil is dry and the leaves are soft.
Another important consideration is planting and transplanting or propagating succulents during the growing season. is best. Again, the temperate climate of the Monterey Bay region moderates temperatures, so gardeners can thrive on succulents most of the year. Good.
Deepen your gardening knowledge
Note 1: The Cactus and Succulents Society of America will host a webinar “Survival of the Fattest” on Saturday at 10am. Presenter Buck Hemenway explores how succulents collect, store and conserve water in South Africa. Hemenway is a longtime cactus and succulent gardener and nursery owner in Southern California and has lived in South Africa in retirement. For more information on this free event, please visit cactusandsucculentsociety.org/.
Reminder 2: The Garden Conservancy will host a virtual program “Small Space Gardening” on January 12th at 11am..Garden designer Jason Williams encourages city dwellers to make the most of their unique growing spaces, including patios, terraces and balcony gardens, in accessible ways.
This event is the first webinar of the Conservatory’s Winter 2023 Virtual Program and is fee-based ($5 for Conservancy members, $15 for general admission). For registration and additional information, please visit www.gardenconservancy.org/education/virtualevents.
Enjoy your garden!
Tom Karwin is Past President of the Friends of UC Santa Cruz Arboretum and the Monterey Bay Iris Society and Past President and Life Member of Monterey Bay Area Cactus & Co. Juicy Society, and Lifetime UC Master Gardener (certified 1999–2009). He is currently on the board of the Santa Cruz Hostel Society and active in the Pacific Horticultural Society. To see daily photos from his garden visit https://www.facebook.com/ongardeningcom-
566511763375123/. For garden coaching information and an archive of previous On Gardening columns, visit http://ongardening.com.
