Answer: A couple of things come to mind. Tomatoes are moisture sensitive and need a regular supply of water throughout their growing season to thrive and produce good-sized fruit. That's especially important here in AZ because of our hot sun and dry conditions. How often to water depends on your particular soil's characteristics. You want to keep it uniformly moist, but not soaking wet, to a depth of about 12 inches.
Another thought is variety selection. The larger the tomato, the greater the difficulty is growing it to maturity in the low desert. Larger fruits take longer to mature, which can be a problem if our heat sets in early. Cracking often develops in larger fruits. Although Best Boy is a mid-size, keep that in mind when choosing varieties. Best Boy is a newer variety and I don't have alot of reports from area gardeners on it yet. I do know that Early Girl and Celebrity perform well here, as do any of the cherry tomatoes.
Finally, when did you set out your transplants? Tomatoes need to be in the ground somewhere between mid-February and mid-March to have time to grow, develop root systems, flower and set fruit before our temperatures get too high. The exact date depends on your microclimate and when your last frost date is. Many gardeners put their tomatoes in about mid-February, but protect against late frosts until mid-March. I hope this info helps.
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