diff --git a/.github/workflows/docker.yml b/.github/workflows/docker.yml
index c6b5b4a8..81c4375f 100644
--- a/.github/workflows/docker.yml
+++ b/.github/workflows/docker.yml
@@ -1,6 +1,9 @@
 name: Build, test, and publish Docker Images
 
 on:
+  schedule:
+    # Weekly, at 03:00 on Monday UTC time
+    - cron: "0 3 * * 1"
   pull_request:
     paths-ignore:
       - ".github/ISSUE_TEMPLATE/**"
@@ -78,19 +81,19 @@ jobs:
         run: make -C main hook-all
 
       - name: Push Wiki to GitHub
-        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main'
+        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main' || github.event_name == 'schedule'
         uses: stefanzweifel/git-auto-commit-action@5dd17c3b53a58c1cb5eaab903826abe94765ccd6 # dependabot updates to latest release
         with:
           commit_message: "[ci skip] Automated publish for ${{github.sha}}"
           repository: wiki/
 
       - name: Login to Docker Hub
-        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main'
+        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main' || github.event_name == 'schedule'
         uses: docker/login-action@f054a8b539a109f9f41c372932f1ae047eff08c9 # dependabot updates to latest release
         with:
           username: ${{secrets.DOCKERHUB_USERNAME}}
           password: ${{secrets.DOCKERHUB_TOKEN}}
 
       - name: Push Images to DockerHub
-        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main'
+        if: github.ref == 'refs/heads/master' || github.ref == 'refs/heads/main' || github.event_name == 'schedule'
         run: make -C main push-all-multi
diff --git a/all-spark-notebook/Dockerfile b/all-spark-notebook/Dockerfile
index 26466863..ec4eda92 100644
--- a/all-spark-notebook/Dockerfile
+++ b/all-spark-notebook/Dockerfile
@@ -24,17 +24,17 @@ USER ${NB_UID}
 
 # R packages including IRKernel which gets installed globally.
 RUN mamba install --quiet --yes \
-    'r-base=4.1.0' \
-    'r-ggplot2=3.3*' \
-    'r-irkernel=1.2*' \
-    'r-rcurl=1.98*' \
-    'r-sparklyr=1.7*' && \
+    'r-base' \
+    'r-ggplot2' \
+    'r-irkernel' \
+    'r-rcurl' \
+    'r-sparklyr' && \
     mamba clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
 
 # Spylon-kernel
-RUN mamba install --quiet --yes 'spylon-kernel=0.4*' && \
+RUN mamba install --quiet --yes 'spylon-kernel' && \
     mamba clean --all -f -y && \
     python -m spylon_kernel install --sys-prefix && \
     rm -rf "/home/${NB_USER}/.local" && \
diff --git a/base-notebook/Dockerfile b/base-notebook/Dockerfile
index 69414117..a780fb41 100644
--- a/base-notebook/Dockerfile
+++ b/base-notebook/Dockerfile
@@ -3,7 +3,7 @@
 
 # Ubuntu 20.04 (focal)
 # https://hub.docker.com/_/ubuntu/?tab=tags&name=focal
-ARG ROOT_CONTAINER=ubuntu:focal-20210609
+ARG ROOT_CONTAINER=ubuntu:focal
 
 FROM $ROOT_CONTAINER
 
@@ -130,9 +130,9 @@ RUN set -x && \
 # Do all this in a single RUN command to avoid duplicating all of the
 # files across image layers when the permissions change
 RUN conda install --quiet --yes \
-    'notebook=6.4.0' \
-    'jupyterhub=1.4.1' \
-    'jupyterlab=3.0.16' && \
+    'notebook' \
+    'jupyterhub' \
+    'jupyterlab' && \
     conda clean --all -f -y && \
     npm cache clean --force && \
     jupyter notebook --generate-config && \
diff --git a/datascience-notebook/Dockerfile b/datascience-notebook/Dockerfile
index c8d99e56..734fcae0 100644
--- a/datascience-notebook/Dockerfile
+++ b/datascience-notebook/Dockerfile
@@ -55,26 +55,26 @@ USER ${NB_UID}
 
 # R packages including IRKernel which gets installed globally.
 RUN conda install --quiet --yes \
-    'r-base=4.1.0' \
-    'r-caret=6.0*' \
-    'r-crayon=1.4*' \
-    'r-devtools=2.4*' \
-    'r-forecast=8.15*' \
-    'r-hexbin=1.28*' \
-    'r-htmltools=0.5*' \
-    'r-htmlwidgets=1.5*' \
-    'r-irkernel=1.2*' \
-    'r-nycflights13=1.0*' \
-    'r-randomforest=4.6*' \
-    'r-rcurl=1.98*' \
-    'r-rmarkdown=2.9*' \
-    'r-rodbc=1.3*' \
-    'r-rsqlite=2.2*' \
-    'r-shiny=1.6*' \
-    'r-tidymodels=0.1*' \
-    'r-tidyverse=1.3*' \
-    'rpy2=3.4*' \
-    'unixodbc=2.3.*' && \
+    'r-base' \
+    'r-caret' \
+    'r-crayon' \
+    'r-devtools' \
+    'r-forecast' \
+    'r-hexbin' \
+    'r-htmltools' \
+    'r-htmlwidgets' \
+    'r-irkernel' \
+    'r-nycflights13' \
+    'r-randomforest' \
+    'r-rcurl' \
+    'r-rmarkdown' \
+    'r-rodbc' \
+    'r-rsqlite' \
+    'r-shiny' \
+    'r-tidymodels' \
+    'r-tidyverse' \
+    'rpy2' \
+    'unixodbc' && \
     conda clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
diff --git a/docs/using/selecting.md b/docs/using/selecting.md
index d01bbf0a..32507846 100644
--- a/docs/using/selecting.md
+++ b/docs/using/selecting.md
@@ -193,23 +193,21 @@ diagram](../images/inherit.svg)](http://interactive.blockdiag.com/?compression=d
 
 ### Builds
 
-Pull requests to the `jupyter/docker-stacks` repository trigger builds of all images on GitHub Actions.
-These images are for testing purposes only and are not saved for further use.
-When pull requests merge to master, all images rebuild on Docker Hub and become available to `docker pull` from Docker Hub.
+Every Monday and whenever a pull requests is merged, images are rebuilt and pushed to the public container registry.
 
-### Versioning
+### Versioning via image tags
 
-The `latest` tag in each Docker Hub repository tracks the master branch `HEAD` reference on GitHub.
-`latest` is a moving target, by definition, and will have backward-incompatible changes regularly.
+Whenever a docker image is pushed to the container registry, it is tagged with:
 
-Every image on Docker Hub also receives a 12-character tag which corresponds with the git commit SHA that triggered the image build.
-You can inspect the state of the `jupyter/docker-stacks` repository for that commit to review the definition of the image
-(e.g., images with tag `33add21fab64` were built from <https://github.com/jupyter/docker-stacks/tree/33add21fab64>.
+- a `latest` tag
+- a 12-character git commit SHA like `b9f6ce795cfc`
+- a date formatted like `2021-08-29`
+- a set of software version tags like `python-3.9.6` and `lab-3.0.16`
 
-You must refer to git-SHA image tags when stability and reproducibility are important in your work.
-(e.g. `FROM jupyter/scipy-notebook:33add21fab64`, `docker run -it --rm jupyter/scipy-notebook:33add21fab64`).
-You should only use `latest` when a one-off container instance is acceptable
-(e.g., you want to briefly try a new library in a notebook).
+For stability and reproducibility, you should either reference a date formatted
+tag from a date before the current date (in UTC time) or a git commit SHA older
+than the latest git commit SHA in the default branch of the
+jupyter/docker-stacks GitHub repository.
 
 ## Community Stacks
 
diff --git a/pyspark-notebook/Dockerfile b/pyspark-notebook/Dockerfile
index c400a882..d6292934 100644
--- a/pyspark-notebook/Dockerfile
+++ b/pyspark-notebook/Dockerfile
@@ -57,7 +57,7 @@ USER ${NB_UID}
 
 # Install pyarrow
 RUN mamba install --quiet --yes \
-    'pyarrow=4.0.*' && \
+    'pyarrow' && \
     mamba clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
diff --git a/r-notebook/Dockerfile b/r-notebook/Dockerfile
index 5a098a4e..8f07d406 100644
--- a/r-notebook/Dockerfile
+++ b/r-notebook/Dockerfile
@@ -26,31 +26,31 @@ USER ${NB_UID}
 
 # R packages including IRKernel which gets installed globally.
 RUN conda install --quiet --yes \
-    'r-base=4.1.0' \
-    'r-caret=6.*' \
-    'r-crayon=1.4*' \
-    'r-devtools=2.4*' \
-    'r-forecast=8.15*' \
-    'r-hexbin=1.28*' \
-    'r-htmltools=0.5*' \
-    'r-htmlwidgets=1.5*' \
-    'r-irkernel=1.2*' \
-    'r-nycflights13=1.0*' \
-    'r-randomforest=4.6*' \
-    'r-rcurl=1.98*' \
-    'r-rmarkdown=2.9*' \
-    'r-rodbc=1.3*' \
-    'r-rsqlite=2.2*' \
-    'r-shiny=1.6*' \
-    'r-tidymodels=0.1*' \
-    'r-tidyverse=1.3*' \
-    'unixodbc=2.3.*' && \
+    'r-base' \
+    'r-caret' \
+    'r-crayon' \
+    'r-devtools' \
+    'r-forecast' \
+    'r-hexbin' \
+    'r-htmltools' \
+    'r-htmlwidgets' \
+    'r-irkernel' \
+    'r-nycflights13' \
+    'r-randomforest' \
+    'r-rcurl' \
+    'r-rmarkdown' \
+    'r-rodbc' \
+    'r-rsqlite' \
+    'r-shiny' \
+    'r-tidymodels' \
+    'r-tidyverse' \
+    'unixodbc' && \
     conda clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
 
 # Install e1071 R package (dependency of the caret R package)
-RUN conda install --quiet --yes r-e1071 && \
+RUN conda install --quiet --yes 'r-e1071' && \
     conda clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
diff --git a/scipy-notebook/Dockerfile b/scipy-notebook/Dockerfile
index 4f82be5b..d0b2c1b9 100644
--- a/scipy-notebook/Dockerfile
+++ b/scipy-notebook/Dockerfile
@@ -17,34 +17,34 @@ USER ${NB_UID}
 
 # Install Python 3 packages
 RUN conda install --quiet --yes \
-    'altair=4.1.*' \
-    'beautifulsoup4=4.9.*' \
-    'bokeh=2.3.*' \
-    'bottleneck=1.3.*' \
-    'cloudpickle=1.6.*' \
+    'altair' \
+    'beautifulsoup4' \
+    'bokeh' \
+    'bottleneck' \
+    'cloudpickle' \
     'conda-forge::blas=*=openblas' \
-    'cython=0.29.*' \
-    'dask=2021.6.*' \
-    'dill=0.3.*' \
-    'h5py=3.3.*' \
-    'ipympl=0.7.*'\
-    'ipywidgets=7.6.*' \
-    'matplotlib-base=3.4.*' \
-    'numba=0.53.*' \
-    'numexpr=2.7.*' \
-    'pandas=1.3.*' \
-    'patsy=0.5.*' \
-    'protobuf=3.17.*' \
-    'pytables=3.6.*' \
-    'scikit-image=0.18.*' \
-    'scikit-learn=0.24.*' \
-    'scipy=1.7.*' \
-    'seaborn=0.11.*' \
-    'sqlalchemy=1.4.*' \
-    'statsmodels=0.12.*' \
-    'sympy=1.8.*' \
-    'widgetsnbextension=3.5.*'\
-    'xlrd=2.0.*' && \
+    'cython' \
+    'dask' \
+    'dill' \
+    'h5py' \
+    'ipympl'\
+    'ipywidgets' \
+    'matplotlib-base' \
+    'numba' \
+    'numexpr' \
+    'pandas' \
+    'patsy' \
+    'protobuf' \
+    'pytables' \
+    'scikit-image' \
+    'scikit-learn' \
+    'scipy' \
+    'seaborn' \
+    'sqlalchemy' \
+    'statsmodels' \
+    'sympy' \
+    'widgetsnbextension'\
+    'xlrd' && \
     conda clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"
diff --git a/tensorflow-notebook/Dockerfile b/tensorflow-notebook/Dockerfile
index 96b78ba1..db9db201 100644
--- a/tensorflow-notebook/Dockerfile
+++ b/tensorflow-notebook/Dockerfile
@@ -8,7 +8,7 @@ LABEL maintainer="Jupyter Project <jupyter@googlegroups.com>"
 
 # Install Tensorflow
 RUN mamba install --quiet --yes \
-    'tensorflow=2.4.1' && \
+    'tensorflow' && \
     mamba clean --all -f -y && \
     fix-permissions "${CONDA_DIR}" && \
     fix-permissions "/home/${NB_USER}"