August means tomato season in Vermont. Our plants are in full production and we are enjoying their bounty.
We grow mostly heirloom varieties that have stood the test of time. We have them today because seeds have been passed down through generations of farmers. Most heirloom varieties are thought to be indeterminate. What? You don’t know what that means?
Well, indeterminate tomatoes will grow and produce fruit until killed by frost. They are vining and may reach heights close to 12 feet although 6 feet is an average. Indeterminates will bloom, set new fruit and ripen fruit all at the same time throughout the growing season. They require substantial staking or trellising for support.
Determinate tomatoes, or "bush" tomatoes, are varieties that grow to a compact height (generally 3 - 4'). Determinates stop growing when fruit sets on the top bud. All the tomatoes from the plant ripen at approximately the same time (usually over period of 1- 2 weeks). They require a limited amount of staking.
Never prune a 'determinate' type tomato. You want all the fruit you can get from these shorter plants. Indeterminate varieties vary in their response to pruning, some reportedly have increased yields when the young plant is pruned back to three or four vines. I prefer to let the plant produce stems for better fruit production and better leaf canopy to protect the fruit from sunscald. Remember that removing new flowers near the end of the growing season can help speed up the ripening of mature fruit.