From our perspective, the terms "soft" and "hardy" are a direct reflection of our evolutionary adaptation to water. As succulents, we all store moisture in our leaves and stems, but our tolerance for its presence and absence differs drastically. Soft succulents, like many Echeveria and Sedum morganianum (Burro's Tail), hail from climates where frost is a death sentence. Our cells are plump and hydrated, much like a juicy grape. If the water within our cells freezes, it expands, rupturing the cell walls and causing irreversible damage. This is why we simply cannot survive freezing temperatures. In contrast, hardy succulents, such as Sempervivum (Hens and Chicks) and many Sedum species, have evolved in mountainous or northern regions. We have developed a kind of internal antifreeze. We can actively move water out of our cells and into the spaces between them, and we increase the concentration of sugars and salts inside our cells, dramatically lowering their freezing point. This allows us to withstand sub-zero temperatures, with some of us surviving down to -30°F (-34°C) or lower.
Our needs for light and warmth are intrinsically linked to our cold tolerance. Soft succulents thrive in consistently warm, bright conditions. We adore basking in full sun for most of the day, as it fuels our growth and helps us maintain our vibrant colors. However, intense, scorching afternoon sun in peak summer can sometimes be too much, even for us, potentially causing sunburn on our tender leaves. Our ideal temperature range is a comfortable 65-80°F (18-27°C). Hardy succulents are far more adaptable. We not only tolerate cold but often require a distinct winter dormancy period with cooler temperatures to thrive and produce offsets in the following growing season. While we also love sunlight, we are generally more resilient to temperature fluctuations and can handle a wider range of light conditions, from full sun to partial shade, without as much risk of stress.
How you water us is perhaps the most critical care difference, and it's all about mimicking our natural rainfall patterns. For soft succulents, think of a desert downpour followed by a long, hot drought. When you water us, you must drench the soil completely, ensuring our entire root system has access to moisture. Then, you must allow the soil to dry out almost completely before the next watering. Our roots are highly susceptible to rot if left sitting in damp soil for prolonged periods. Hardy succulents, while also drought-tolerant, are often accustomed to more frequent, lighter rains or morning dew, even in colder weather. Our root systems are a bit hardier and can handle soil that doesn't dry out quite as quickly, especially during our active growing seasons in spring and fall. However, the universal rule for all succulents is that excellent drainage is non-negotiable. Soggy soil is a death sentence for both of us, but for soft succulents, it's a swift one.
The composition of our soil directly impacts our root health and, consequently, our entire being. Both soft and hardy succulents demand a gritty, exceptionally well-draining mix. However, the ideal blend can vary. Soft succulents often prefer a mix with even more inorganic material, such as perlite, pumice, or coarse sand—sometimes as high as a 50/50 or even 70/30 ratio of inorganic to organic matter. This creates an environment where water flows through instantly and air can circulate freely around our delicate roots. Hardy succulents, especially those planted in the ground, can often tolerate a slightly heavier soil, as garden soil naturally provides more stability and moisture retention. Nevertheless, amending in-ground planting sites with gravel or sand is still highly beneficial for us to prevent waterlogging during wet winters or heavy rains.
