diff --git a/changelog/14557.doc.rst b/changelog/14557.doc.rst
new file mode 100644
index 00000000000..38d10046375
--- /dev/null
+++ b/changelog/14557.doc.rst
@@ -0,0 +1 @@
+Clarified that conftest files discovered during collection are not available for hooks which run before collection, such as :hook:`pytest_sessionstart` and :hook:`pytest_report_header`.
diff --git a/doc/en/how-to/writing_plugins.rst b/doc/en/how-to/writing_plugins.rst
index 56043a14f97..386eb8f5f65 100644
--- a/doc/en/how-to/writing_plugins.rst
+++ b/doc/en/how-to/writing_plugins.rst
@@ -59,6 +59,11 @@ Plugin discovery order at tool startup
      After a ``conftest.py`` file is loaded, recursively load all plugins specified
      in its :globalvar:`pytest_plugins` variable if present.
 
+   These initial conftest files are loaded before collection starts. Conftest
+   files discovered later during collection can still implement hooks, but they
+   are not available for hooks which run before collection, such as
+   :hook:`pytest_sessionstart` and :hook:`pytest_report_header`.
+
 
 .. _`conftest.py plugins`:
 .. _`localplugin`: