Question: Do heirloom tomatoes take longer to grow than hybrids? I’ve had heirloom tomato seedlings in raised beds for about six weeks, and they keep growing taller, but not forming fruits.
Answer: Most tomatoes don’t bear fruit until well after six weeks in the ground, so it’s possible that you’re still up to four weeks from tomato production, a period that involves almost unbearable anticipation.
Tomatoes are typically divided into indeterminate and determinate types. Determinates mature to a certain size and then bear all of their fruit in a short period of time — a positive quality in a paste tomato, such as ‘Martino’s Roma,’ as it provides a large amount of fruit at once for processing and canning.
Indeterminate types bear fruit as they grow, and their vines grow indefinitely — although we tend to think of tomatoes as annuals, in warm climates, they’re perennials. You may see fruit set more quickly on these cultivars because they set fruit over a longer season — ideal for fresh eating.
As for whether heirlooms bear fruit more slowly than hybrids, every cultivar has its own pace of bringing fruits to maturity, and some heirlooms, especially those selected for cooler parts of the country, may bear more quickly regardless of being determinate or indeterminate. A trait known as “hybrid vigor,” or “out-breeding enhancement,” thought to result from genetically distinct parents, can lead some hybrids to be more prolific, or perhaps even quicker to mature, than heirlooms, which have genetically similar parents. Hybrid vigor was one of the arguments for the creation of hybrid cultivars, and scientists continue to examine how the phenomenon works, but the exact genetic mechanism remains unclear.
-Lee Buttala, Seed-Saving Expert
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