Does the size of your pot affect the size of the fruit?

[Maylar]

I have some Roma and Better Boy tomatoes growing in pots on my deck. Both are producing fruit but they're small compared to what they should be. Also some red bells that are small too. Can it be just because the pots are too small?

 

[Chuck]

It could be, however there are other factors involved as well a pot size. Nutrients, water, amount of sunshine, temperatures and soil makeup all contribute to amount and size of fruit. Having said all of this, if you were to grow a tomato in a small pot versus one in a large container and everything stated above was equal, the amount and size of the fruit grown in the small pot would be inferior to the fruits in the large container. I know this because I have seen it for decades. IMO the smallest container for a tomato variety such as a Roma or Better Boy is a 5 gallon one and on indeterminate varieties 7 gallon and larger. On peppers I consider a 3 gallon as absolute minimum size.

 

[Meadowlark]

Can it be just because the pots are too small?

Welcome @Maylar. Yes, all things being equal, the size of the container can definitively affect the size of the tomato produced.

Here's a table that defines the minimum size required for different tomato types. Personally I grow indeterminates in 25+ gallons containers.

Tomato Type	Minimum Pot Size	Expected Fruit Impact
Cherry / grape	3–5 gallons	Small fruit anyway, but yield increases with bigger pots
Determinate (bush)	7–10 gallons	Fruit size improves noticeably with larger pots
Indeterminate (vining)	15–20+ gallons	Large fruit varieties (beefsteak, heirloom) require big pots for full-size fruit

 

[Ruderunner]

Huh, I knew the plant would be limited, didn't think that would really affect fruit size though.

 

[Chuck]

Huh, I knew the plant would be limited, didn't think that would really affect fruit size though.

Yep, it surely does. I did an experiment with Cherokee Purple and Celebrity one time. 5 plants of each both in ground and in 10 gallon fabric containers. 20 total plants. The CP's in ground produced an average of 21 bs per plant with 8 tomatoes over 2lbs. and one tomato at 3 lbs 2 oz. The container grown CP's averaged 18 lbs per plant with only 1 tomato exceeding 2 lbs. Celebrity's are classified as a semi-determinate. The Celebrity plants normally grow a little bigger than regular determinates. The Celebrity's averaged 19 pounds in the ground and 16 lbs in containers. I didn't keep track of how much the largest tomatoes weighed but the tomatoes produced were all of comparable sizes of 10 oz or so. This was done in South Texas and a limited growing season because of high temperatures. Experiment was done in the 2009 spring summer growing season.

 

[Meadowlark]

Huh, I knew the plant would be limited, didn't think that would really affect fruit size though.

That is a very easy one to test in your own experiment.... try it.

 

[big rockpile]

Think about what the plant is doing above ground it is basically doing the same below ground.

Tomatoes love room to grow and the more confined the roots the smaller they will grow.

I have also found they like loose Potting Soil and will go crazy with roots

big rockpile