If you ask for tomatoes in May at a local farmers market in Illinois, the response will be somewhere between laughter and a simple no. The ground doesn't get warm enough here for tomato plants to bloom until July at the earliest, sometimes August. But being the stubborn person that I am, I decided to attempt to fool Mother Nature. I started some tomato seeds in January in my basement. I used fluorescent lights and grow mats. And I was successful. It was too successful in some ways. I had more little plants than I had large pots for them to be transplanted.
My first tomatoes started to grow on a Japanese plum variety, but they quickly began to show signs of blossom end rot. Then the green zebras bloomed, and I hand pollinated them (referred to as "tomato sex" by my children and AI by another family member). The first four zebras are rapidly approaching ripeness. The lighter green stripes will turn yellow when ripe, and the darker green stripes will stay green -- hence the name, green zebra. They'll be about four ounces when mature, or the size of a large egg. They're one of my favorite tomatoes, and they make an excellent quiche with goat cheese!
The rest of the tomato plants are still hanging out in the greenhouse, not looking so great. Hope they survive after transplanting. I'm currently working on hardening off the potted tomato plants so they can spend the summer on the deck, and when fall comes, I can bring them back inside to extend the harvest into winter!