Seeds Trust Southwest was our quest to find the best tasting and most reliable regionally adapted seeds. We offer seeds from trials and testing in gardens around our previous location in Cornville, Arizona. We have enjoyed exploring the region’s historically deep and diverse offerings and making the best available to you. Many of our most cold-tolerant Siberian tomatoes have surprised us as well and survived, even thrived in the hot climate. A more accurate description for them might be extreme-temperature tolerant.