Answer: Too much nitrogen results in a lot of lush, green vegetative growth but poor fruit productions. Tomatoes are referred to as "heavy feeders"; they require quite a large food supply over the season. It is a good idea to add some fertilizer to the soil at planting time. A mix such as 5-10-10 is preferable. You want to concentrate on the potassium and phosphorous for tomatoes. Tomatoes also require a "side dressing" of fertilizer a few times throughout the growing season. Generally, this side dressing is applied when the first tomatoes have just formed and every three weeks after that. When side dressing apply the fertilizer by making a circular furrow approximately 5-6" away from the main stem of the tomato. Work the fertilizer into the top 1-2" of the soil. The next rain or watering will carry the fertilizer to the root zone of the tomatoes. The amount you apply will be dependent upon the type, size, number, etc. of tomatoes you are growing. Check your fertilizer label for exact amounts. Also, have you had a soil test recently? If your pH is very low or very high,it can interfere with nutrient uptake. You can contact your Cooperative Extension office for details about a soil test. One other thing, you mention using manure on your garden, are you using fresh or composted? Fresh manure really shouldn't be used on your plants, it is very "hot" (high in nitrogen) and can burn your plants.
You might also try heat-tolerant variety, just to see if that could be a factor. Heatwave is definitely a good one to try. Also, Hawaiian VFNT Hybrid is heat-tolerant and delicious; Gulf State Market is an old variety popular in the Gulf states; Arkansas Traveler is a southern heirloom; Tropic VFT was developed for Florida's climate; and Cherokee Purple is an heirloom from Tennessee. Heatwave is available from Burpee, and all of these varieties are available from Tomato Growers Supply, P.O. Box 2237, Fort Myers, FL 33902, (941) 768-1119.
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