Karl Foord, UMN Extension Educator
There is little doubt that one of the best taste treats in a Minnesota Summer is a vine ripe tomato. In this case I am referring to a vine that you grew and a tomato that you picked when you decided it was ripe. In addition the distance it had to travel to your kitchen is measured in feet not thousands of miles. As an aside where did tomatoes come from in the first place?
Photo 1: Tumbler. Karl Foord.
Tomatoes were first domesticated by early Indian civilizations of Mexico. Cultivars were taken to Europe in the mid 1500's and then back to North America by colonists in the early 1700's. Tomatoes were slow to catch on because of their similarity to the poisonous belladonna of the nightshade family. The appeal for tomatoes took hold in the middle of the 19th century. In 1863 there were 23 known cultivars whereas in 1883 there were several hundred cultivars. Presently there are around 7,500 cultivars with a great variety of fruit sizes shapes and colors. Tomatoes also demonstrate different plant types commonly classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height. Note the mass of flowers positioned above the foliage in the variety 'Tumbler'. Indeterminate varieties develop into vines that never top off and continue producing until killed by frost. Note the smaller inflorescence of flowers located nestled within the vine in the variety 4th of July.
Photo 2: Fourth of July.Karl Foord.
Photo 3: Tumbler flowers. Karl Foord.
One goal would be to have tomatoes for as long a period during the summer as possible, and one strategy to achieve this is based on variety selection. Many but not all of the early maturing tomato varieties are determinate; however an early maturing determinate tomato is a good way to start the season. An early maturing indeterminate variety will keep fruit coming connecting early and later maturing determinates as well as the late season indeterminates.
There are advantages and disadvantages to growing tomatoes in containers. The advantages may include avoidance of; damage by critters, problems associated with soil born diseases, and most leaf diseases because the leaf surfaces dry quickly when containers can be placed in an airy location such as an elevated deck. The ambiance created by container tomatoes on a deck or patio is very appealing.
Photo 4: Container varieties. Karl Foord.
The disadvantage of containers is water related. Because determinant and indeterminate varieties develop into different size plants they have different combined leaf surface areas and thus different water needs especially at maturity. The indeterminate vines can get big and require a lot of water. If they are grown in small pots that dry quickly the plant will experience problems associated with constant water stress, one of which is blossom end rot. One way to avoid this is to select a pot size related to the tomato cultivar's growth type. In this way one can avoid the water stress problem by having a large enough pot that will hold enough water permitting the plant to be watered only once a day.
A demonstration of variety type matched to pot size is on display at the Minnesota Landscape Arboretum as part of the Powerhouse Plants exhibit.
This demonstration shows 5 different cultivars of various growth types and maturity dates in several different pot sizes (Table 1 and photo of varieties).