Answer: Threre are only three apple cultivars that do well in Florida.
They are the Anna, Dorsett Golden and the Ein Shemer. I have grown all three. I have done very well with the Anna and the Dorsett, but the Ein Shemer did not do well at all.
In your case, I would keep the seedlings and see what they will do. Remember, however, that apples do not reproduce true to type; that is, the fruit you get from your seedlings (assuming you are able to get fruit) may not resemble the parent fruit. Often, the fruit harkens back to the parent's ancesters, and may be small, bitter, or otherwise undesirable. On the other hand, it might also be wonderful!
Young apple trees should be pruned to a modified leader system. On two- year-old trees five or six strong scaffold limbs should be selected to develop a strong framework. These limbs should have wide angles almost perpendicular to the trunk of the tree, should be radially spaced around the tree trunk and vertically spaced approximately 6" to 8" from each other up or down the trunk. Later pruning of the tree will be to remove diseased or dead wood and to trim the tree to the desired shape.
Apply one pound of a 10-10-10 fertilizer for each year of growth. Apply half of the recommended amount of fertilizer in January and the other half in June. The fertilizer should be broadcast evenly beneath the tree.
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