How big do tomatillo plants get? sprawling plants grow 3 to 4 feet tall and at least as wide. Greenhouse Seeding/Propagation Dates April – early May. Field Transplanting Dates Late May – early June. Optimal Soil temperature at planting >15°C Optimal Temperature Range 24 - 32°C Days to harvest 80-100 days after transplanting. omafra.gov.on.ca