WordPress Cron and Scheduled Tasks

WP-Cron is a pseudo-cron that fires on page load. On production with consistent traffic, replace it with real server cron.

Schedule an Event

// Register on plugin/theme activation
if (!wp_next_scheduled('my_daily_cleanup')) {
    wp_schedule_event(time(), 'daily', 'my_daily_cleanup');
}

// Hook the callback
add_action('my_daily_cleanup', 'run_daily_cleanup');

function run_daily_cleanup() {
    global $wpdb;
    // Delete expired transients
    $wpdb->query(
        "DELETE FROM {$wpdb->options}
         WHERE option_name LIKE '_transient_timeout_%'
         AND option_value < " . time()
    );
}

// Clean up on deactivation (IMPORTANT — don't leave orphan events)
register_deactivation_hook(__FILE__, function() {
    wp_clear_scheduled_hook('my_daily_cleanup');
});

Custom Schedule Intervals

add_filter('cron_schedules', function($schedules) {
    $schedules['every_15_minutes'] = [
        'interval' => 900,
        'display'  => 'Every 15 Minutes',
    ];
    $schedules['every_6_hours'] = [
        'interval' => 21600,
        'display'  => 'Every 6 Hours',
    ];
    return $schedules;
});

Replace WP-Cron With Real Server Cron

Step 1 — Disable WP-Cron in wp-config.php:

define('DISABLE_WP_CRON', true);

Step 2 — Add real cron job (runs every 15 minutes):

# Via crontab -e
*/15 * * * * /usr/local/bin/wp cron event run --due-now \
  --path=/var/www/html --quiet

# Or via PHP directly
*/15 * * * * /usr/bin/php /var/www/html/wp-cron.php > /dev/null 2>&1

WP-CLI Cron Management

# List all scheduled events
wp cron event list

# Run all due events immediately
wp cron event run --due-now

# Check when specific event runs next
wp cron event list --fields=hook,next_run_gmt | grep my_daily_cleanup

# Delete a stuck event
wp cron event delete my_daily_cleanup

# Test cron (simulates triggering)
wp cron test

Built-In WordPress Schedules

| Interval | Slug | Seconds | |----------|------|---------| | Every hour | hourly | 3600 | | Twice daily | twicedaily | 43200 | | Daily | daily | 86400 | | Weekly | weekly | 604800 |