The tomatillo (Physalis philadelphica) is a staple of Mexican cuisine, often called the Mexican husk tomato. It is a warm-season annual fruit, not a true tomato, that resembles a small, firm, green tomato encased in a distinctive, papery wrapper. This fruit is prized for its bright, tart flavor, which is a defining characteristic in many Latin American dishes.
Botanical Identity and Unique Features
The tomatillo belongs to the nightshade family (Solanaceae), making it a relative of the tomato, potato, and pepper plants. Its growth habit is bushy and sprawling, with indeterminate stems that can reach three to five feet, often requiring support like a cage or trellis. The leaves are large, simple, and heart-shaped.
The most identifying characteristic is the papery, lantern-like husk, called the calyx, that completely envelops the developing fruit. This husk forms from the flower’s protective outer leaves and expands as the fruit grows inside. The fruit is a small berry, usually one to two inches in diameter.
While the fruit is edible, all other parts of the plant, including the husk and leaves, contain toxic alkaloids and are not safe for consumption. The fruit is typically vibrant green when harvested, though certain cultivated varieties can mature into yellow or purple hues.
Essential Cultivation Requirements
Tomatillos thrive as a warm-season crop, requiring full sun and a long, frost-free growing season. They should only be transplanted outdoors after all danger of frost has passed. Planting them in fertile, well-drained soil that is consistently moist helps ensure vigorous growth.
Cross-pollination is required for successful fruit production, as tomatillos are highly self-incompatible. A single plant cannot effectively pollinate its own flowers to set fruit. Gardeners must plant at least two different tomatillo plants, and preferably three or four, to ensure insects can transfer pollen between them.
Without cross-pollination, flowers will drop off without forming the husk-covered fruit. Spacing the plants about three feet apart allows for adequate air circulation and growth. A tomato cage or stakes will help manage their sprawling, indeterminate nature. Consistent watering at the base is necessary, as the plants require about one to one and a half inches of water weekly.
Harvesting and Culinary Uses
The fruit is ready for harvest approximately 60 to 75 days after transplanting. The most reliable sign of ripeness is the husk itself. The fruit is mature when it has fully expanded to fill the papery calyx, causing the husk to become taut and often begin to split or peel back. The ripe fruit is firm and usually maintains its bright green color, although some varieties turn yellow or purple upon full maturity.
Once harvested, the fruit must be removed from its dry, tan husk. Beneath the husk, the fruit often has a sticky, sappy residue that must be washed off before cooking. This cleaning step is important before the fruit is chopped or processed.
The primary culinary use for the tomatillo is in salsa verde, the vibrant green sauce fundamental to Mexican cuisine. The fruit is valued for its tart and acidic flavor profile, which provides a sharp contrast to the sweetness of a traditional red tomato. While green fruit is preferred for savory sauces, yellow or purple varieties develop sweetness when fully ripe, making them suitable for jams or preserves.