4×4 bed
A small 4×4 bed is usually best with a few supported tomato plants, not a full dense block.
Tomato spacing
How far apart should tomatoes be in a raised bed?
Most raised-bed tomatoes need about 18 inches or more between plants, plus support and airflow. Cramming too many tomatoes into a small bed usually lowers harvest quality.
Give tomatoes airflow
Tomatoes are productive, but they are not small plants. Leave enough room to prune, water at soil level, and harvest without snapping stems.
Use vertical support
Cages, stakes, panels, or string trellises let tomatoes grow upward instead of spilling across paths and shading nearby crops.
Pair with lower crops
Basil, lettuce, scallions, and other compact crops can use nearby space early in the season, but keep them from competing with mature tomato roots.
4×8 bed
An 8 foot trellis row can support several tomatoes while leaving room for herbs or quick greens.
Avoid crowding
Crowded tomato beds dry unevenly, lose airflow, and are harder to inspect for pests or disease.
Next step
Run your bed dimensions through the tomato calculator before deciding how many seedlings to buy. Open the calculator with these defaults, or check the monthly sowing calendar before you plant.