Half strength fertiziler.

If the directions call for one tablespoon per gallon of water a half strength solution would be one tablespoon per two gallons of water. Twice the amount of water will give you a half strength solution.

Whether you should fertilize during winter or not depends on your setup. If you are keeping them warm and giving them plenty of light they will be trying to grow and will need fertilizer if they aren't getting enough from the soil. Tropicals are the only trees/plants that should be in that situation in the winter IMHO. *The few tropicals I grow are in the basement and kept around 50 degrees and very low light. *I don't fertilize them because they can't use it and don't need it in this state. They will rest there until I put them outside in the spring. Then the fertilizer program will star again.

Tony