How do I choose container sizes?
Written by
Paul Reynolds
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Choosing pot sizes Traditionally, we would choose the size pot depending on the intended mature size of the plant, not the size of the plant when it starts. If the pot is too small, the roots get restricted, and the plant suffers. A much larger pot wastes compost and contains excess moisture. It should fit the depth and spread appropriate for that plant.
Volume Requirements
- Herbs thrive in 1-3 gallon (3.8-11.4L) pots
- Fruiting plants need 5+ gallons (19L+)
- Large vegetables require 10+ gallons (38L+)
- Match soil volume to expected root mass
Depth Considerations
- Carrots need 12+ inch (30cm) deep pots
- Lettuce requires 6-8 inch (15-20cm) depth
- Tomatoes benefit from 12-18 inch (30-45cm) depth
- Match container shape to root type
Root-bound plants will give you ample warning if they are too small for their container. Roots circling the surface or showing through drainage holes? Slowed growth? Pot them in larger containers before this occurs. As a general rule, the diameter should match the mature spread of the leaves.
Container materials influence sizing decisions. Unglazed clay loses moisture quickly, necessitating larger sizes to compensate for this loss of moisture. Plastic retains water, allowing for slightly smaller pots. Fabric pots air-prune roots, naturally preventing binding. Consider material when determining your plants' finished containers.
My first tomatoes languished in small pots until I repotted them into sizable pots (they were pleased when I did!). A few weeks later, they'd doubled in size! That was the day I learned to always research the mature size of a plant before planting it. Now I keep two inches (5 cm) for them to grow into from the edge of their containers.
Read the full article: 10 Essential Container Gardening Tips for Beginners
