By Ron Filson and James Campbell >> IJ correspondents

When the first big rains of the season arrive in Marin County, we all know it’s time to adjust our outdoor watering routines for the cooler months. While it might be tempting to turn off your irrigation system entirely, winter watering isn’t as simple as flipping a switch. Even dormant plants need water during the winter, and inconsistent rainfall means that careful planning is key to keeping your garden healthy through the season.

Here are some practical tips for maintaining your irrigation system and ensuring your plants thrive during Marin’s winter months:

• Don’t turn off the water just yet. It’s natural to assume your garden won’t need additional watering during the rainy season, but that’s not always the case. Marin’s rainfall can be unpredictable, and dry spells between storms can stress plants.

Even in winter, plants under overhangs, eaves or in sheltered areas often don’t receive enough rain. Container plants are especially vulnerable because their limited soil dries out faster than garden beds. Check these areas regularly and water as needed. If the soil in your containers becomes excessively dry, it can actually resist water absorption, making rehydration a challenge. Avoid this by keeping the soil consistently moist, but not soggy.

• Leverage your irrigation system. Modern irrigation systems can simplify winter watering, especially if you make use of features like inline shut-off valves. These allow you to selectively water specific areas, like container plants or beds under overhangs, without overwatering sections of your garden that receive ample rain.

If your controller includes a “seasonal adjustment” setting, take advantage of it. This feature lets you reduce the watering schedule to nearly zero during the rainy season. Just remember to reset it when the

weather warms up again. If you’re using a WaterSmart controller or a system that relies on web-based climate data, ensure that the weather station it’s linked to accurately reflects your garden’s microclimate. If not, don’t worry — many modern controllers are highly customizable, and there’s a wealth of online resources, including YouTube tutorials, to help you fine-tune your programming.

For a more personalized approach, consider scheduling a visit from the Marin Master Gardeners’ Marin Garden Walks program. This free service provides tailored advice for improving water efficiency in your garden and is an invaluable resource for Marin homeowners.Winter is an ideal time to inspect your irrigation system and make sure it’s running efficiently. Here’s a quick checklist to keep things in top shape:

• Check for leaks. Inspect hoses, emitters and connectors for cracks or leaks. Small issues can waste a surprising amount of water.

• Clear clogs. Debris can accumulate in emitters or drip lines. Clean out clogs to ensure water flows where it’s needed.

• Adjust spray patterns. Ensure sprinklers aren’t watering sidewalks, driveways or already soaked areas. Redirect them to target only plants.

• Test the controller. Confirm your controller is programmed correctly for winter conditions. If your system includes rain sensors, test them to ensure they’re working properly.

• Stay observant. No matter how advanced your irrigation system is, the best way to ensure your garden’s health is to spend time observing it. Look for signs of stress, such as drooping or yellowing leaves, which might indicate overwatering or underwatering. Remember, healthy soil is the foundation of a thriving garden, so make sure it stays moist but not saturated.

By taking the time to adjust your irrigation practices for winter, you’ll not only conserve water but also support the long-term health of your plants. With a little care and attention, your garden will be ready to bloom beautifully in the spring.

Sponsored by UC Cooperative Extension, the University of California Marin Master Gardeners provides science- and research-based information for Marin home gardeners. Email questions to helpdesk@marinmg.org. Attach photos for inquiries about plant pests or diseases. Please call 415-473-4910 to see when a master gardener will be at the office or drop off samples 24/7 in the sample box outside the office. To attend a gardening workshop or subscribe to Leaflet, a free quarterly e-newsletter, go to marinmg.ucanr.edu.