The tomatillo, often called the husk tomato due to its distinctive papery covering, is a warm-weather crop foundational to Mexican cuisine. Botanically classified as Physalis ixocarpa or Physalis philadelphica, this fruit is famously used to create the tangy, bright flavor of salsa verde. While related to the tomato, the tomatillo possesses a unique tartness and firmness, thriving in sunny conditions.
The Tomatillo Growth Timeline
The timeline for tomatillo fruit production depends on the initial planting method. Transplants offer a quicker path to harvest, typically producing mature fruit 60 to 75 days after being moved outdoors. Sowing seeds directly into the soil extends the total time until harvest, often requiring 85 to 100 days for the plant to reach maturity and begin producing. This difference is due to transplants having an initial four to six weeks of indoor growth, effectively shortening the time spent in the garden.
Once the plant begins to flower, the next major stage is the development of the fruit inside the calyx, which forms the papery husk. After successful pollination, the small fruit inside the husk can take 50 to 70 days to fully expand and ripen. Tomatillo plants are indeterminate, meaning they continuously produce new flowers and fruit throughout the summer. This allows the fruit set to mature in continuous waves, enabling weekly harvests until the first frost.
Essential Conditions for Fruit Set
For a tomatillo plant to transition from flowering to setting fruit, certain biological and environmental conditions must be met, as it is not a self-pollinating species. Tomatillos exhibit self-incompatibility, preventing a plant from fertilizing its own flowers. Cross-pollination is a strict requirement for fruit development, so gardeners must cultivate a minimum of two separate tomatillo plants. This transfer is primarily facilitated by insects, such as bees.
Consistent warmth is the most significant environmental factor affecting the plant’s ability to set fruit. The plants require a long, warm growing season and are highly sensitive to cold, making it necessary to wait until all danger of frost has passed before planting. Extreme fluctuations in temperature can cause fruit set failure. Temperatures that drop below 55 degrees Fahrenheit or rise above 90 degrees Fahrenheit may cause the plant to drop its flowers before fertilization occurs.
Tomatillo plants need high light exposure to fuel robust flowering and fruit growth. A location that provides a minimum of six to eight hours of direct sunlight each day is necessary to support the plant’s high yield potential. Without adequate light, even perfectly pollinated flowers may not develop into fully mature fruit. The combination of sufficient sunlight, warm temperatures, and the presence of a second plant for cross-pollination are the factors that enable the plant to begin its fruiting cycle.
Indicators of Harvest Readiness
The most reliable sign that a tomatillo is ready for harvest is the physical condition of the husk surrounding the fruit. As the fruit inside reaches maturity, it will swell to completely fill the papery calyx, causing the husk to become taut. This expansion often results in the husk splitting or bursting open, a clear visual cue that the fruit is ripe. The husk may also change color, turning from a vibrant green to a drier, light tan or even purple hue, depending on the variety.
The fruit itself should be firm to the touch when ready to pick, which is a departure from the softness of a ripe tomato. Most commonly grown green varieties are at their peak flavor when they are a bright green color; if the fruit begins to turn yellow, it indicates overripeness and a loss of the characteristic tangy flavor desired for salsa. Mature fruit should detach easily from the plant with a gentle pull. Harvesting the fruit with the husk still attached is the standard practice, as the husk protects the sticky surface of the fruit and aids in storage.