Ever wonder exactly what an "heirloom" tomato is? This post explains the details, but you can also find out first-hand on Aug. 21 at Project Grow's 10th annual Tomato Tasting at the Ann Arbor Farmers Market from 10 a.m. to noon.

The event is a great way to see and taste the varieties local gardeners are growing. If you have home-grown tomatoes you would like to submit to the tomato tasting, drop them off in bags labeled by variety at the office of the market's manager, Molly, on Aug. 21 before 10 a.m. Event volunteers will gather and prepare them for tasting.

A second tasting for later-season tomatoes will take place at the Farmers Market during the HomeGrown Festival on Sept. 11 from 6 p.m. to 9 p.m.

Heirlooms versus hybrids
You may be wondering what the heck the difference is between heirloom and "normal" (hybrid) tomatoes.

A hybrid tomato (or a hybrid of any other plant) was created from two different varieties of parent plants. The offspring — the hybrid — has the characteristics of both parents, for example pest resistance from one parent and a nice aroma from the other.

The seeds from a hybrid plant will not be true to the parent plant. If you collect seeds from a hybrid vegetable that you grew, the plant resulting from those seeds will not be the same as the plant from which you gathered the seeds. It may revert to either of its parents or become something else altogether. If you want to grow hybrid plants, it's best to buy the seeds so you're sure of what you're getting.

Producers of hybrid seeds have to control the seed production very closely, and often hand-pollinate the seeds. Common tomato hybrids include Better Boy and Early Girl. A personal favorite hybrid tomato is Red Short Vine.

Because hybrids have been optimized, they tend to have more uniform shapes and disease resistance "built in." As such, most vegetables in grocery stores are hybrids. Hybrid seeds grown in the home garden will have a lot more flavor than those that need to be picked early and shipped great distances.

Heirloom means two things: the variety is at least 50 years old* and is open-pollinated, meaning it is done by bees, not by hand. Heirloom seeds have often been passed from generation to generation. Heirlooms are not a genetic combination of more than one variety, and their seeds will be true to the parent plant. If you save seeds from heirloom plants you grow, the seeds will grow into the exact same plant as the one you got the seeds from.

Common varieties of heirloom tomatoes include Brandywine, Green Zebra and Black Krim. Personal favorites include (but are not limited to!) Tiger-Like, Gajo de Melon and Black Russian.

Heirloom tomatoes may look a little different from what you're used to seeing at the store. They come in a wider range of colors (green, white, yellow, orange, purple and nearly black), and the shapes can be a little less uniform. But the taste, ooh, the taste is so rich and wonderful. But you don't have to take my word for it, come on Saturday and try it for yourself!

As a home grower, I prefer heirlooms because I love to try new varieties and there are hundreds of heirlooms available. I used to grow hybrids and have not personally noticed any inferiority in the disease resistance of heirlooms. However, I am an organic gardener with a large variety of other plants, so I have a lot of beneficial insects which keep pests of all kinds in check. You can pick whichever type suits your own needs, and remember anything you grow in your own garden is going to be fresher and tastier than what you can buy.

Helpful links
- More detailed information on heirlooms, hybrids, and open pollination.
- The Tomato Gardener, a blog by metro-Detroit veggie expert Colleen Vanderlinden.
- Heirloom gardening classes, free sessions by Project Grow each spring.

If you attend the tasting, leave a comment as to your favorite tomato. Heck, even if you don't go, let me know your favorites!

* Not to confuse the matter, but even experts don't agree exactly on the number of years that makes a plant heirloom — I've heard anything from 30 to 50, but I personally side on older.

Monica Milla, the Garden Faerie, is a master gardener volunteer, garden speaker, garden coach, and author of "Fun with Winter Seed Sowing."