Tomatillos are a vibrant, tart fruit central to Mexican cuisine, most notably as the base for authentic salsa verde. The fruit develops inside a thin, papery husk, giving it the appearance of a small lantern. Growing tomatillos from seed allows you to cultivate specific varieties and ensure a healthy start for a prolific harvest. This guide provides a detailed process for successfully growing these unique plants.
Starting Seeds Indoors
Tomatillos, like their nightshade cousins, require a long, warm growing season, making an indoor start essential for most climates. You should aim to sow your seeds about six to eight weeks before the last expected frost date in your area. This timing ensures the seedlings are mature enough to transplant but have not yet become root-bound or overly leggy indoors.
To promote successful germination, use a sterile seed-starting mix in trays or small containers. Plant the tiny seeds shallowly, covering them with approximately one-eighth to one-quarter inch of soil. The most important factor for quick sprouting is consistent warmth; the soil temperature should ideally be maintained between 70°F and 85°F, which is often achieved with a seedling heat mat.
Once the seedlings emerge, usually within one to three weeks, the temperature can be slightly reduced to between 65°F and 70°F. A bright light source is immediately necessary to prevent stretching, such as a strong grow light positioned just a few inches above the foliage for 14 to 16 hours daily. Ensure the growing medium remains consistently moist, but never soggy, to support healthy root development. If the seedlings become too large before outdoor planting, pot them up into slightly bigger containers, burying a portion of the stem deeper to encourage a stronger root system, similar to how you would handle tomato plants.
Transplanting and Ensuring Pollination
Transitioning seedlings outdoors requires gradual acclimatization, known as hardening off. Over the course of a week to ten days, expose the seedlings to increasing periods of outdoor sun and wind, starting with just one or two hours in a shaded location. This process toughens the plant tissues and prevents shock when they are permanently moved outside.
Tomatillos are sensitive to cold, so transplanting should only occur well after all danger of frost has passed and the soil temperature has warmed to at least 60°F. Select a permanent spot that receives a minimum of six to eight hours of direct sunlight, as this heat-loving plant thrives in full sun. Preparing the soil by incorporating well-aged compost will improve drainage and add organic matter, creating the ideal growing environment.
A crucial biological requirement for a successful harvest is the need for cross-pollination. Tomatillos are self-incompatible, meaning an individual plant’s flowers cannot pollinate themselves. For fruit set to occur, you must plant at least two tomatillo plants, which allows insects to transfer pollen between the separate individuals. Space your plants about two to three feet apart to allow for their bushy, sprawling growth habit.
Routine Plant Care and Support
Tomatillo plants require consistent moisture, especially once they begin to flower and set fruit, though they are more drought-tolerant than tomatoes. Deliver water deeply at the base of the plant, aiming for about one to one and a half inches of water per week. Watering in the morning and avoiding overhead irrigation helps prevent fungal diseases by allowing the foliage to dry out quickly.
Fertilization should be handled cautiously to prevent excess leaf growth over fruit production. If your soil was enriched with compost at planting, additional fertilizer may not be necessary. If you do choose to fertilize, apply a balanced or low-nitrogen formula once the plants have begun to flower. Excess nitrogen promotes lush, green foliage at the expense of fruit yield.
As the plants mature, they develop a sprawling, indeterminate growth habit, often reaching three to four feet in height and width. Support is recommended to keep fruit off the soil, improving air circulation and reducing disease risk. Staking the main stem or using tomato cages are effective methods for managing the plant’s bushy nature. Installing the support system at the time of transplanting prevents later root damage that could be caused by driving stakes into the ground near established plants.
Harvesting Ripe Tomatillos
The unique indicator of a ripe tomatillo is the papery husk, which offers visual and tactile clues. Initially, the husk is green and much larger than the fruit, but as the fruit matures, it completely fills the husk. For most varieties, the fruit is ready for harvest when it has swollen enough to split or burst open the husk, which may also turn tan or light brown.
To check for ripeness, gently squeeze the husk to feel the firmness of the fruit inside; it should feel solid and have completely filled the outer covering. The fruit inside will be firm and bright green for most common varieties, though some cultivars ripen to yellow or purple. A ripe tomatillo will detach easily from the plant with a light tug or twist.
After picking, the fruit is often covered in a sticky residue that should be washed off before use. It is best to leave the husks intact until just before preparation, as this covering aids in short-term storage. Unhusked tomatillos can be stored in a paper bag in the refrigerator for up to several weeks, making them a convenient ingredient for fresh salsa verde.