Are Haworthia Winter Growers?

In my last newsletter, I mentioned that "I usually don’t water them (Haworthia) at all during December and January, except for young seedlings." This sparked a response from a reader who pointed out, "Haworthia are winter growers."

This comment highlights a common belief: that Haworthia are winter growers. For many years, I accepted this as fact. However, my experience cultivating these plants over the past two decades has revealed a more nuanced story.

Are Haworthia Winter Growers?

Conventional wisdom among some is that Haworthia are winter growers, but under cultivation, my plants behave differently. In my growing conditions, they grow more actively during autumn and spring. This observation led me to rethink their natural growth cycles and the environmental conditions in their native habitats.

Haworthia Habitats: More Than Winter Rainfall

The habitats of Haworthia in South Africa are arid but not true deserts. These regions often receive light rainfall year-round, with varying peaks depending on the locality.

For example, when I visited a habitat of Haworthia bayeri near Uniondale in December 2006 (South African summer), it began to rain just as we located the plants. The picture at the top is one I took of H. bayeri at that locality.   This challenged my assumption that summer is always a dry season in these regions.

Comparing Rainfall Patterns

To illustrate, consider the Namib Desert, home to desert specialists like Lithops and Welwitschia. The Namib receives an average of just 3 mm of rainfall per month during its rainy season:

In contrast, Haworthia habitats receive significantly more rainfall. For example, here’s a rainfall map for Oudtshoorn, one of the habitats of H. truncata, H. picta, and other species:

While Oudtshoorn sees most of its rain in winter, some areas experience higher rainfall in autumn and spring. Consider Uniondale and Albertinia (a habitat of H. splendens):

These data underscore that while Haworthia habitats are arid, they are not true deserts. Rainfall patterns are diverse and not exclusively tied to winter.

Adapting Watering Practices in Cultivation
So, how should we water Haworthia in cultivation? Here’s what I’ve learned through trial and error:

Avoid Summer Watering During Heat Spells:
Watering during the hottest parts of summer can cause root loss in some plants. To prevent this, I shade my plants and keep them relatively dry during peak summer heat.

Minimize Winter Watering:
While Haworthia can tolerate winter moisture, I’ve found that watering during the coldest months (December and January in my region) can lead to rotting of the outer leaves. As a result, I avoid watering altogether during this period, except for young seedlings.

Focus on Active Growth Seasons:
My plants are most active in autumn and spring, so I water regularly during these periods. 

Conclusion
Haworthia are adaptable plants that evolved in arid climates with varied rainfall patterns. Understanding their natural habitats helps refine our cultivation practices, but observing your plants and adjusting to their specific needs is equally important.

For me, a balance of autumn and spring watering, combined with summer shading and winter rest, has been key to keeping my Haworthia happy and thriving.