Question: This year I want to grow tomatoes from seed instead of buying whatever transplants I can find. Some of my gardening friends told me the best tasting tomatoes are heirloom varieties like Brandywine. What are heirlooms? How are they different from other tomatoes? Do heirlooms taste better? B.N.
Answer: Heirloom or open-pollinated plants are varieties that have stable traits from one generation to the next. Open pollinated plants are chosen for one or two specific characteristics. Therefore, individual plants of heirloom varieties may differ greatly in size, shape, and other traits.
Heirlooms are grown in fields where they self and cross-pollinate. Wind or insects carry pollen from one plant to another. Plants that cross-pollinate must be isolated from other plants of different varieties so they will produce seed that is “true to type.”
Genetic “drift” can occur over time. Plants that deviate too far from the accepted standard are removed from commercial production fields of open pollinated varieties. Removal of these rogue plants prevents them from pollinating other plants and producing too much variation. Home gardeners might do the same to preserve an open pollinated variety or let it go to see if something better develops.
The advantage of open pollinated seed is gardeners may from year to year, and generation to generation, continue heirloom plants by careful seed saving. Open pollinated plants also provide a diverse gene pool for future breeding.
Hybrid seeds are produced by crossing specific parent plants using controlled pollination. Hybrid plants have very specific characteristics. The term “hybrid” is strictly defined in the seed industry and, when used in catalogs, does not apply to plants naturally crossing in the wild – there are many examples of Mother Nature producing hybrids all by herself.
Hybrids have what is commonly called “hybrid vigor”, meaning better seedling survival, larger and stronger plants, and higher yields. Because they are very consistent genetically, hybrids are uniform from plant to plant and from year to year than non-hybrids. Some hybrids are specifically bred for disease or insect resistance.
Seed from hybrid plants will not produce plants identical to the parent, so the seeds should not be saved from year to year. Offspring of hybrids usually show an unpredictable mixture of characteristics from the grandparent plants.
Some people think heirloom vegetables taste better. But taste is so subjective that you really need to make your own decision. I suggest you try a combination of heirloom and hybrid varieties this year. Compare the taste and other characteristics. Then, in future, you can choose varieties that you like best.
Barb Larson is horticulture educator for Kenosha County University of Wisconsin Extension. Barb has a Master’s of Science in horticulture from the UW-Madison. If you have a plant or gardening question, email Larson at firstname.lastname@example.org or call her at 262-857-1945.