From our perspective as Nerine plants, our primary vulnerability to frost and freeze lies in our bulb and foliage. We are native to South Africa, meaning our cellular structure is not adapted to endure the formation of ice crystals. When temperatures drop below freezing, the water within our cells freezes, expanding and rupturing the delicate cell walls. This irreversible damage manifests as blackened, mushy leaves and, in severe cases, can lead to the rotting of our bulb—our lifeline and stored energy source for the next growing season. Even a light frost can scorch our flower stalks and developing blooms, preventing our reproductive display.
Your choice of where to plant us is our first and best defense. We implore you to situate us in a microclimate that offers natural protection. Plant our bulbs against a south or west-facing wall or foundation. These structures absorb heat during the day and radiate it slowly throughout the night, raising the immediate ambient temperature around us by several critical degrees. Similarly, planting us on a slope allows cold, dense air to drain away to lower areas, preventing us from sitting in the coldest air pocket. Positioning us under the canopy of a deciduous tree can also provide a protective blanket, shielding us from radiant heat loss on clear, cold nights.
While our foliage dies back after flowering, our bulb remains alive and dormant below the soil surface. The soil itself is a remarkable insulator, but in northern zones, it is not enough. After the ground has chilled in late autumn but before a hard freeze, apply a thick, loose layer (4-6 inches) of mulch over our planting area. Use materials like straw, pine needles, shredded leaves, or bark chips. This layer does not heat the soil but traps the earth's residual geothermal warmth, preventing rapid temperature fluctuations and insulating our bulb from the killing cold above. Think of it as tucking us in with a thick, protective winter duvet.
For unexpected early autumn or late spring frosts that threaten our tender new growth and blooms, we require immediate, short-term shelter. When frost is forecast, please cover us in the evening. Use breathable fabrics like burlap, old sheets, or commercial frost cloths—never use plastic, as it can trap excessive moisture and conduct cold directly to our foliage. Drape the material over stakes to create a tent, ensuring it extends to the ground to trap soil heat. Remember to remove this covering first thing in the morning once temperatures rise above freezing to allow for ventilation and sunlight.
If you have chosen to grow us in containers, our situation is far more precarious. Our roots and bulb are exposed to the cold on all sides, with no insulating mass of the earth. We cannot survive a northern winter above ground in a pot. Before the first hard freeze, you must move our container to a cool, dark, but frost-free location. An unheated garage, shed, or basement where temperatures remain consistently between 35-50°F (2-10°C) is ideal. This allows us to enter a proper dormancy without being subjected to fatal freezing temperatures. Please water us very sparingly during this period, providing just enough moisture to prevent our bulbs from desiccating completely.
