Brussels sprouts like cool weather. In Florida, it is best to plant them outdoors from October through December. In warm weather, the sprout heads will form loosely, as you are experiencing. It also sounds like your plants are beginning to bolt (flower), which occurs in warmer weather. The top of the plant will elongate and form flowers. This can affect the quality of your sprouts. You can try to delay this a little by removing the top part of the plant where the flowers are forming, to encourage the lower sprouts to mature. Some say that applying a little nitrogen might also help to delay bolting.
Brussels sprouts like cool weather. In Florida, it is best to plant them outdoors from October through December. In warm weather, the sprout heads will form loosely, as you are experiencing. It also sounds like your plants are beginning to bolt (flower), which occurs in warmer weather. The top of the plant will elongate and form flowers. This can affect the quality of your sprouts. You can try to delay this a little by removing the top part of the plant where the flowers are forming, to encourage the lower sprouts to mature. Some say that applying a little nitrogen might also help to delay bolting.