The other day I was watching a new show on PBS here in San Diego called, “A Growing Passion”, which talks about native plants, growing vegetables, etc. Right down my alley! The host visited a farmer’s market and talked with a new company called “Mighty ‘Mato“. They do something that has been around for centuries…a little thing called grafting. They take a disease/pest resistant root stock and hand-graft it to tomatoes and eggplants. Not only does this allow once delicate heirlooms to be grown resistant to disease, but they also grow about twice the size of their original counterpart. Armstrong Nursery carries Mighty ‘Matos and I went to check them out yesterday. When I saw what variety they had, I about fell on my bum.
Indigo Rose is not only an amazing hippie name, but it’s also the name of a truly purple tomato variety out of Oregon State University, bred for it’s high anti-oxidant level. It’s so new to home gardeners, that this year’s season is the first to be able to grow them.
So, you guess it, Mighty ‘Mato has grafted Indigo Rose to grow twice as big and resist disease, including the root knot nematodes living happily in my garden (grrrrrr). Boy I snatched one up faster than you can say “purple caprese salad”.
Here’s Indigo Rose. Even the leaves have a purple tinge to them.
The pot is hard to miss!
New things for the garden help keep things fun and fresh. I’ll let you know how Indigo Rose does!
Bountiful Backyard 
I’m not so sure about it being the darkest tomato bred so far. Look at David’s (The Gastronomic Gardener) Black Prince!
http://www.gastronomicgardener.com/black-tomatoes-and-other-garden-updates/
Good luck with the grafted tomatoes.
I have root knot nematodes also. I did some research last year and found that mustard is supposed to help kill them. I grew it in a bed that was totally infested. So far the plants seem to be doing very well. We will see what happens when I remove them at the end of the season.