Tomatillo

The single most important fact about tomatillos is biological, not cultural: they are self-incompatible. A single tomatillo plant in full flower and full health will produce almost no fruit. The pollen cannot successfully fertilize the same plant it came from. To get fruit, you need at least two plants — preferably from different seed sources — growing close enough that bees can carry pollen between them. This is not a garden myth or a preference. It is how the plant's reproduction works, and not knowing it is why a lot of first-time tomatillo growers end up with lush, flowering vines and no harvest.

Start seeds indoors six weeks before your last frost date, much as you would tomatoes. Tomatillo seeds germinate readily in warm soil and the seedlings grow fast. Transplant after your last frost date, when the nights are reliably above 50°F. Space plants 24 inches apart. The plants tend to sprawl — they are not compact, and their branches can reach four or five feet in multiple directions — so staking or a large cage is worth setting up at transplant time. Unlike tomatoes, tomatillos are not usually pruned; let them branch freely.

Tomatillos are more drought-tolerant than tomatoes and do not need as consistent a watering schedule, but they set fruit best with regular, moderate moisture. Avoid overfeeding with nitrogen-heavy fertilizers; a plant with too much nitrogen will put energy into foliage rather than fruit. The flowers are small and yellow, easily overlooked. After pollination, the papery husk that surrounds each fruit begins to form and expand — the fruit is developing even before you can see it clearly.

The husk is the harvest indicator. When a tomatillo is ready, the husk will have fully filled out, feel taut or splitting, and the fruit inside will have turned from pale yellow-green to a darker, more saturated green (or in some varieties, purple or yellow). A common mistake is harvesting fruit when the husk is still loose and papery-small around it — at that stage the fruit is immature and the flavor is thin and acidic. Wait until the husk is full and beginning to crack. The fruit should feel firm but give slightly to thumb pressure.

Tomatillo plants are more productive and longer-season than most gardeners expect. A good planting of two to three plants can yield enough fruit to make salsa verde repeatedly through the summer and into fall. The plants handle moderate heat well and often outlast tomatoes in a long, warm season. At the end of the season, any unharvested fruit that falls to the ground will self-sow readily — so readily, in fact, that tomatillo volunteers in unexpected corners of the garden are common the following year.