Determining Your Tomato Type

Jesse Fulbright, MSU Liberty County Extension

As an undergraduate, I took some sort of course (I forget what exactly) where we spent considerable time in a greenhouse setting.  During part of that time we had the opportunity to start tomatoes from seeds, and I, in my infinite wisdom, decided to plant approximately 200 tomato seeds.  It’s obvious now that I wasn’t thinking of the long-term and the fact that I had then to transplant a great deal of those plants as well as they grew.  It was a lesson learned and we had a lot of tomatoes to plant in our small section of the student housing garden that summer.

When looking at growing tomatoes, a question has been posed to me about what the difference is between a determinate and an indeterminate tomato.  I’ll just say upfront that in our environment, our tomatoes, whether determinate or indeterminate, are going to act in a determinate fashion.  Determinate cultivars of tomatoes are those that grow to a couple of feet in height, stop, flower and set fruit.  Indeterminate cultivars grow through the season, sometimes making up to 15 feet of vine growth.  I think of those large plants that grow in greenhouse settings.  Indeterminate cultivars set fruit as they go and continue to produce up to frost.  That’s why I said that those two types effectively operate as determinate in our environment, as frost and cold temperatures are the limiting factors.  The fruit of indeterminate varieties also ripen over an extended period of time. 

Illustration courtesy of UC ANR.

 

Speaking from a MontGuide publication that is available to the public, determinate types form compact plants that may not need to be supported.  You might choose to have a support them anyway, as both types usually benefit from some kind of support.  Indeterminate types trail along the ground if they are not supported.  The plant foliage keeps the soil cool and moist and can delay fruit ripening.  Supporting your plants will help fruit ripen earlier. 

Whether you have determinate or indeterminate cultivars, set them in the garden after the danger of frost is passed.  For us, I would count on after Memorial Day.  Having cloches around them, such as the walls of water, can protect them further from chilly night-time temperatures to a certain extent, and can also protect against wind damage.  Other tools, such as plastic milk jugs or old tires could also accomplish the same tasks for the most part.