The word heirloom is bandied about a lot. Most people just take it mean old-time as per grungy's description. They can be true family heirlooms, or just old-time commercial releases like the tomatoes that A.W. Livingston introduced from 1870 onwards. Some people only mean family heirlooms when they use the word. In terms of growing, there's absolutely no difference between growing a tomato that was developed and released yesterday, and one that's been around for a couple of hundred years. As grungy pointed out, many modern hybrids are developed for storage and transport, taste kinda gets lost one the way. Since you're growing for your own consumption and don't really need to ship your tomatoes anywhere or cool store them for weeks on end, then I'd explore the heirlooms more. Many have superb flavour, and they variety of shape, size and colour is just astounding. As far as disease resistance is concerned, I haven't noticed, nor have I seen anyone report an appreciable difference between modern hybrids and the old-timers. For good choices for your zone, post your question on the tomato forum, where there are many very knowledgeable people only too willing to share their knowledge. Hope this helps.

I'm not sure if these are all proper heirlooms or simply OP, but I've grown Black Plum in the past & it tasted wonderful in 1 area & yucky in another - the only difference I could figure out was that the yucky-tasting 1s were planted near my papayas - & I've had the same effect w/ other tomatoes as well I grew black Cherry this year & it was really delicious - not a heavy bearer, but I had only 1 plant. Last year, grape tomatoes(seed saved from store-bought fruit) were super delicious as well & gave me lots of fruits. I'm dying to grow Hillbilly tomatoes again - they were by far the most beautiful & luscious fruits - very large & very few seeds & the plant seemed to do better when the weather got hot. Speckled Roman is another I liked very much.

The picture is exactly what my green zebras look like. They are ripe when they are yellow and green. Yours look good to me. It is everyones favorite. A wonderful citric flavor. Go enjoy it! Yum.

Hi Marianne, Most of the heirloom tomato talk is on the tomato forum. Some excellent reading and people with strong opinions. But since we're here, I have a variety of favorites: Cherokee Purple, Aker's West Virginia, Earl's Faux Red Brandywine are all fabulous. I also love Red Brandywine. They all pack a fabulous tomato punch to my way of thinking. Do look at the tomato seed exchange forum as well. You'll notice the link on the tomato forum. Sometimes people will offer seeds for free, or the price of a self addressed stamped envelope. All the best. Mary