diff --git a/cardano-testnet/changelog.d/20260226_005016_palas_default_to_update_timestamps.md b/cardano-testnet/changelog.d/20260226_005016_palas_default_to_update_timestamps.md
new file mode 100644
index 00000000000..6c71cd105e2
--- /dev/null
+++ b/cardano-testnet/changelog.d/20260226_005016_palas_default_to_update_timestamps.md
@@ -0,0 +1,9 @@
+### Added
+
+- Added `--preserve-timestamps` flag. When set, genesis file timestamps are kept as-is.
+
+### Changed
+
+- Timestamps in genesis files are now updated to the current date by default.
+- The `--update-time` flag is now internal (hidden, kept for backward compatibility).
+
diff --git a/cardano-testnet/src/Parsers/Cardano.hs b/cardano-testnet/src/Parsers/Cardano.hs
index 0275b9cfa3f..89a3dd5c45d 100644
--- a/cardano-testnet/src/Parsers/Cardano.hs
+++ b/cardano-testnet/src/Parsers/Cardano.hs
@@ -134,11 +134,14 @@ pMainnetParams = OA.flag' OnChainParamsMainnet
   )
 
 pUpdateTimestamps :: Parser UpdateTimestamps
-pUpdateTimestamps = OA.flag DontUpdateTimestamps UpdateTimestamps
-  (  OA.long "update-time"
-  <> OA.help "Update the time stamps in genesis files to current date"
-  <> OA.showDefault
-  )
+pUpdateTimestamps =
+  -- Default to UpdateTimestamps, because when using the two-step flow
+  -- (cardano-testnet create-env → cardano-testnet cardano --node-env),
+  -- genesis timestamps can become stale.
+  -- See https://github.com/IntersectMBO/cardano-node/issues/6455
+  OA.flag' UpdateTimestamps (OA.long "update-time" <> OA.help "Update the time stamps in genesis files to current date (default, kept for backward compatibility)" <> OA.internal)
+  <|> OA.flag' DontUpdateTimestamps (OA.long "preserve-timestamps" <> OA.help "Do not update the time stamps in genesis files to current date.")
+  <|> pure UpdateTimestamps
 
 pEnvOutputDir :: Parser FilePath
 pEnvOutputDir = OA.strOption
diff --git a/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli b/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
index 5b49e6538d9..7560ea5978c 100644
--- a/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
+++ b/cardano-testnet/test/cardano-testnet-golden/files/golden/help.cli
@@ -13,7 +13,7 @@ Usage: cardano-testnet cardano [--num-pool-nodes COUNT]
   [--slot-length SECONDS]
   [--active-slots-coeff DOUBLE]
   [--node-env FILEPATH]
-  [--update-time]
+  [--preserve-timestamps]
   [--params-file FILEPATH | --params-mainnet]
 
   Start a testnet and keep it running until stopped
diff --git a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
index 50b9eb7e8cb..18cbac06741 100644
--- a/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
+++ b/cardano-testnet/test/cardano-testnet-golden/files/golden/help/cardano.cli
@@ -11,7 +11,7 @@ Usage: cardano-testnet cardano [--num-pool-nodes COUNT]
   [--slot-length SECONDS]
   [--active-slots-coeff DOUBLE]
   [--node-env FILEPATH]
-  [--update-time]
+  [--preserve-timestamps]
   [--params-file FILEPATH | --params-mainnet]
 
   Start a testnet and keep it running until stopped
@@ -51,8 +51,8 @@ Available options:
                            otherwise). You can generate a default environment
                            with the 'create-env' command, then modify it and
                            pass it with this argument.
-  --update-time            Update the time stamps in genesis files to current
-                           date
+  --preserve-timestamps    Do not update the time stamps in genesis files to
+                           current date.
   --params-file FILEPATH   File containing custom on-chain parameters in
                            Blockfrost format:
                            https://docs.blockfrost.io/#tag/cardano--epochs/GET/epochs/latest/parameters