There are several steps you can take to reduce the size of a Docker container that is increasing due to garbage:

1. Use the docker system prune command to remove all stopped containers, networks, and dangling images.
2. Use the docker container prune command to remove all stopped containers.
3. Use the docker image prune command to remove all dangling images.
4. Use the docker volume prune command to remove all unused volumes.
5. Use the docker network prune command to remove all unused networks.
6. Use the docker rmi command to remove unnecessary images. You can use docker images command to list all images and docker rmi <image_id> command to remove an image.
7. You can also use multi-stage builds. It allows you to use multiple FROM statements in your Dockerfile. This can help you build a smaller image by copying only the artifacts you need from one stage to the next, instead of copying the entire filesystem.
8. You can also run docker history <image_name> command to see what layers are in the image, and use docker save command to save the image to a tar file, you can inspect the tar file and see what files are taking up space.
9. Also, you can use .dockerignore file to ignore unnecessary files while building the image.
10. Finally, you can also consider using an external service like JFrog Artifactory, Google Container Registry or Amazon Elastic Container Registry (ECR) to store and manage your images.

By following these steps, you should be able to significantly reduce the size of your Docker container and keep it from increasing due to garbage.