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Become a Smarter Gardener in 2019: Get the right container for your veggies!

Photo: Mary Meyer, UMN Extension
How big a container do you need to grow a tomato? Kale or lettuce? Rosemary or basil? The larger the plant, the bigger the container required to grow and produce food. Pick the right one, and you'll get a better harvest this summer!

What's the right size?

Tomatoes like 'em big!  Use at least a 12" diameter pot, but overall larger is better. Larger pots provide more soil and hold more water which minimizes wilting and stress as plants get large. See the table below that matches plant type to container size.

What's your container made out of? 

Avoid using metal containers, which can absorb too much heat and be deadly to plant roots. Roots cannot tolerate extreme high or low temperatures that upper plant parts can take. Black containers can also be very hot for roots in full sun conditions. Light colored containers are best at minimizing hot conditions.

Soil & Fertilizer

Lightweight potting soil is good for container vegetables and herbs. Adding slow release fertilizer with the potting soil is a good idea. Read the label on the soil mix to see if fertilizer is included. Applying liquid fertilizer weekly is a good rule of thumb.

Very large containers can be filled on the bottom 1/3 or ¼ with crushed milk jugs to minimize using large amounts of soil, if necessary.

Watering & Maintenance

Container vegetables and herbs need to be located in full sun and will need watering daily as the plants grow and begin to produce. Watering in the middle of the day can cool the containers and roots.  All containers should have good drainage--no water should stand around plant roots.

A handy size chart

The chart below shows container sizes for popular vegetables and herbs. You can experiment with your own variation, but remember bigger is better when growing vegetables in containers.

Table1. Vegetables and herb with container size and comments.
Plant
Minimum Size
Preferred Size
Number of Plants
Comments
Basil
1 gallon; 6-7 inch diameter
2 gallon; 8-9 inch diameter
3-4
Mildew resistant: Prospera®
 or Amazel TM harvest and water regularly
Parsley
1 gallon; 6-7 inch diameter
2 gallon; 8-9 inch diameter
2-4
Flat or curly leaf; harvest and water regularly
Leaf lettuce; spinach
1 gallon; 6-7 inch diameter
2 gallon; 8-9 inch diameter
3-4
Prefers cool weather; harvest and water regularly
Green beans
2 gallon; 8-9 inch diameter
5 gallon; 12 inch diameter
2-4 plants; space 3 inches apart
Bush Blue Lake; Provider or other bush bean
Rosemary
1 gallon; 6-7 inch diameter
2 gallon; 8-9 inch diameter
1
Shady Acres
Peppers
2 gallon; 8-9 inch diameter
5 gallon; 12 inch diameter
1-2
Ace, New Ace; Lady Bell
Determinate tomato
5 gallon; 12 inch diameter
10-15 gallon; 16-18 inch diameter
1
Patio, Bush Early Girl; Celebrity
Indeterminate
tomato
5 gallon; 12 inch diameter
10-15 gallon; 16-18 inch diameter
1
Sweet 100; Super Sweet 100; Sungold; Early Girl
Kale
2 gallon; 8-9 inch diameter
5 gallon; 12 inch diameter
1-2
Winterbor; cold tolerant

Other resources

Minnesota Master Gardener recommended varieties: https://extension.umn.edu/planting-and-growing-guides/master-gardener-seed-trials

Karl Foord, former Extension Horticulturist, "How-to" video on container or vertical gardening on a deck or patio:

Cornell recommended vegetable varieties: 

Author: Mary H. Meyer, Extension Horticulturist & Professor


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