Install a 5-foot stake behind each tomatillo plant during the first week after planting. Alternatively, place a tomato cage over the young plants to provide support as they grow.
Water tomatillos deeply one or two times a week, depending on how quickly the soil dries. Supply between 1 and 1 ½ inches of water per plant, or enough to moisten the top 6 to 8 inches of garden soil.
Weed between the plants and rows at least once a week, especially when the tomatillos are young and not large enough to compete well with weeds. Pull weeds between plants by hand to avoid disturbing the tomatillo roots. Hoe or till the top 1 to 2 inches of soil between the rows to kill any new weeds.
Lay a 2-inch layer of straw mulch between the tomatillo plants and rows once the seedlings are 8 inches tall. Mulch suppresses weed growth, insulates the soil and retains moisture in the soil.
Tie the main stem of the tomatillo to the stake with plant ties as it grows, if applicable. Space the ties every 8 inches along the stem. Caged plants don't require tying.
Harvest tomatillos after the husk becomes brown, brittle and begins to split open. Pick the fruits while green and before they develop a yellow color. Use immediately or store refrigerated for up to one week.