How to Build a Smart Garden That Keeps Working When Internet Goes Down

A smart garden is convenient—as long as the internet is available. Once it goes down, however, so do your devices, and without them, your plants may suffer from overheating or lack of water.

If you have or plan to build a smart garden, it’s wise to design it to be independent of an internet connection. This is particularly true in rural areas, which still trail urban areas in fixed broadband coverage. Nationwide, roughly 10.5 million Americans still lack access to it.

Here’s a guide to designing a smart garden that keeps working without an internet connection.

Run the System Locally

The most important design choice is to build your garden around local control. This means that the devices in your garden can rely on a locally hosted controller for instructions.

In cloud-dependent setups, devices send data to the manufacturer’s server, the server processes it, and then sends back a command. When the internet goes down, this process breaks, and your devices stop working. In a local setup, your devices instead rely on the local computer (often called a “hub”).

One way to build a hub is with Home Assistant, a free, open-source software that connects your sensors, valves, and vents from different brands and runs your schedules and rules without contacting an outside server. It can even run on low-power computers, such as a Raspberry Pi or a mini PC. Note that you'll also need sensors and valve controllers that work with local hubs, as some only work through a manufacturer's app and usually need an internet connection.

Additionally, most people will manage their garden through a Windows computer or an Android mobile app. More experienced users may prefer a customizable Linux-based hub; if you plan to access one while using public Wi-Fi, you can download a VPN for Linux to help protect your internet traffic.

Regardless of how you access the system, essential functions such as watering and ventilation should operate locally rather than depend on remote access. Some features may still require an external internet connection, including remote monitoring, cloud-delivered notifications, and watering adjustments based on online weather forecasts. If configured for local operation, schedules, sensor-based automations, and the dashboard on your home network can continue working during an internet outage.

Protect the Power

Power outages can stop a local system, even when the internet is working. While routine outages are usually short, longer ones still occur occasionally.

In 2024, for example, the U.S. Energy Information Administration reported that hurricanes and other major events helped push the average duration of electricity interruptions to 11 hours per customer.

As such, you may want to consider investing in a solar generator or power station, since routers, valve controllers, and hubs don’t use much power. However, devices such as a well pump use much more, so you need to decide whether to back up only the control equipment or the pump as well.

To estimate the battery size you need, multiply each device’s wattage by its expected runtime, add the results, and then include extra capacity for conversion losses and a safety margin. The result is the watt-hours of capacity required. Plug the router into backup power too, so your home network stays up.

Add Mechanical Backups

It’s also advisable to add backups that don't depend on power or the internet for your most important tasks, namely, ventilation and watering.

For example, for ventilation, here are some non-electric options that help prevent overheating if you have a greenhouse:

• Wax-cylinder vent openers contain wax that expands as the air warms, which pushes the vent open. They can also be used in cold frames.
• Roof and side vents let hot air rise out the top while cooler air comes in low.
• Shade cloth blocks sunlight.

For watering:

• A mechanical hose timer, a wind-up dial that works like a kitchen timer and needs no batteries, shuts the water off after a set time, up to about two hours.
• A rain barrel set above your garden beds and connected to drip lines (hoses that release water slowly at the plant roots) can water by gravity, with no power.

Keep in mind that a mechanical hose timer must be started manually, while conventional vents may need to be opened by hand.

Plan for Reconnection

Even with local control, you'll still want internet access when it's available, especially for remote monitoring and alerts. These habits help you manage the system during an outage and when you reconnect:

• Let the hub keep its own records, so no data is lost while you're offline.
• Keep a phone hotspot (your phone's cellular data, shared with other devices) as a temporary connection for alerts.
• Avoid port forwarding, a router setting that exposes a device directly to the internet, as a way to reach your hub remotely.

Conclusion

By following the steps above, your devices can take care of your plants even without connecting to the internet.