Temperature
For germination, the University of Minnesota recommends 75-85°F (24-29°C), then about 70°F (21°C) after emergence.
Growing guide
Start seedlings warm and bright, harden them gradually, then transplant after frost when the soil has warmed.
For germination, the University of Minnesota recommends 75-85°F (24-29°C), then about 70°F (21°C) after emergence.
Provide strong overhead light as soon as seedlings emerge to limit weak, stretched growth.
Start indoors about five to six weeks before the intended outdoor planting date.
Use clean containers and sterile soilless germination mix. Check the packet for growth habit, days to maturity and disease-resistance codes.
Sow about 1/4 inch (6 mm) deep in moist germination mix.
Use steady bottom warmth if needed and monitor moisture because heated trays dry faster.
Remove the cover after emergence and keep light close enough for compact growth.
Over one to two weeks, expose seedlings to more outdoor sun and wind while protecting them from freezing temperatures.
Plant outdoors after frost danger has passed and the soil has warmed. Install stakes or cages at planting.
Oversized indoor seedlings are harder to manage and do not guarantee an earlier harvest.
Bush and vining tomatoes grow differently. Match support and pruning to the cultivar habit.
Cold soil and frost can stall or damage this warm-season crop.
In climates with a short warm season, starting indoors is usually more reliable. Direct sowing is practical only where the frost-free season and soil warmth are sufficient.
No. Pruning and support depend on whether the variety is determinate or indeterminate and on the growing system.