October 9, 2026

How to set up a raised bed irrigation system by bed

The easiest irrigation to run in a raised bed is drip tubing, a loop or a few parallel runs on a timer. It soaks the root zone slowly and loses little water to wind or evaporation. No length of tube tells you which bed is dry, so the setup that saves the most water pairs drip with a soil-moisture probe in each bed. Each probe reads its own bed, so you open the valve on the dry one and leave the wet beds closed.

Steps to set it up

We run it this way in our own garden, where three of our four raised beds carry a probe.

• Lay the drip line. Run parallel lines of drip tubing down the bed, spaced about a foot apart. A 39-inch-wide bed like ours takes about three runs to wet the whole surface.
• Add a valve per bed. Give each bed its own valve or timer zone so you can water one bed without the others.
• Set a probe at root depth. Push a soil-moisture probe into each bed in the spot that dries first.
• Map the probe to the bed. Name each sensor for its bed in the station screen, so a reading carries the bed's name.
• Open the dry bed. Turn on the valve for the bed the sensor shows dry, and leave the rest closed.

With a connected soil probe, Siltwell sends a per-bed dry alert when that bed's two most recent readings both fall below 25%, the default for every bed. The message names the bed and the reading. That turns the last step into a push notification instead of a daily walk with a meter.

Same-size beds dry at different rates, because roots, sun, and mulch differ from bed to bed. From mid-July to mid-September in our garden, raised bed 3 swung from 32% to 62% moisture, while raised bed 1 held tighter, 39% to 54%. Both are 94 by 39 inches. None of ours crossed 25% in that window, so a single whole-garden timer would have overwatered the steady bed every time it ran long for the swingy one.

What can go wrong

• A probe reads one spot. A bed can be wet at the sensor and dry in a far corner, so set the probe where the bed dries first and water to that reading.
• Rain-skip is garden-wide. The watering guidance on Today holds the whole garden after about 5 mm of rain; it does not skip bed by bed. The per-bed signal is the probe.
• The threshold is fixed. Every bed alerts at 25% capacitive moisture; no screen sets a different number per bed.
• Alerts need a connected sensor. Without one, Siltwell gives forecast-based watering guidance for the whole garden, not a per-bed dry alert.

Start with one probe in the bed you water most by guess, map it, and watch a week of readings before you trust the alert. See connecting a soil sensor to a bed for the wiring, and running drip where the soil is dry for the tubing layout.