Field Manual

Coronado Box Window Boxes with built-in Irrigation

How the Coronado Box Irrigation System Works

Coronado Boxes are self-contained fiberglass window boxes, with a double-walled water reservoir for irrigation. The reservoir needs to be filled by hand every 2-4 weeks, depending upon the plant types and location. The reservoir fill hole is plugged with a stopper, creating an air-tight, closed reservoir.

The water in the reservoir flows into the soil through tiny holes along the bottom of the inner liner. The water wicks its way up through the soil until it reaches the moisture sensor, planted 1/3-way down the liner. Only one sensor is used per Coronado Box, no matter the number of water inlet holes (which varies depending upon the length of the liner). The sensor tip absorbs water, and closes like a valve, preventing air from passing through the tube into the reservoir.

A vacuum develops above the reservoir, preventing water from flowing into the soil. As the plants use the moisture and the soil starts to dry, the sensor tip dries and allows air to pass through. The vacuum is broken, allowing water to flow into the container, until the soil becomes moist again.

The process forms a cycle, interrupted only by the removal of the stopper and the filling of the reservoir. The overflow drainage adapter at the side of the unit allows excess water that builds up (typically rainwater) to escape without disrupting the system.

Prior to Planting

1. Inspect Coronado Boxes after delivery for signs of damage during transit, and ensure that all parts are intact. If Coronado Boxes appear damaged, or parts are missing, keep packaging materials and contact Planter Technology.
2. When putting in a long-term planting, Planter Technology recommends the use of BioGuard fabric (sold separately) to prevent the growth of roots into the water reservoir. One Bioguard square is placed (either side up) with each white disc at the base of the inner liner. Use gloves when handling Bioguard, and observe precautions on package.
3. The copper tube extending from the side of Coronado Box is the exterior drainage adapter. Do not remove the factory-fitted drainage pad taped in place. The adapter allows excess water to overflow after heavy rains, but prevents soil from washing out. Tubing may be attached to the drainage adapter to channel overflow directly to the drainage system.

Planting

Place one white 3" disc over each water inlet along the bottom of the inner liner. Take long sheet of landsape fabric, and line the bottom of the unit. Fabric will typically extend part way up the sidewalls of the liner. Firmly pack a layer of soilless potting mix in bottom of Coronado Box. Adjust level of soil so that when plant is set in place, the top of rootball is 1" below the fill hole level. Remove plants from their nursery containers and place inside the Coronado Box. Make sure plants are at the same level. Pack potting soil tightly between each plant and throughout the entire Coronado Box, so no air pockets remain around or between plants.

Dip sensor in water for a full 15 seconds. Use a small stake, screwdriver, pen or similar tool to make a hole in the soil for the sensor, at a 45° angle, in front of where the sensor is attached to the sidewall. Extend sensor down hole so that it extends between 1/3 and 1/2 way down planter liner. Plants that need more water or in brighter locations should be set 1/3 way down, deeper for lower water use plants in darker locations.

Filling and Maintenance

Remove the stopper, being careful not to get soil into the reservoir. Fill reservoir with water halfway initially. After the first week check that the water level in the reservoir is lower than the original fill level and the topsoil appears dry – this will indicate that the system is functioning properly. Thereafter, fill reservoir completely every 2 to 3 weeks, depending on the plant or flowers and its environment. Refill before reservoir is empty. Moisten stopper and replace with a firm, downward twist. Stopper must provide air-tight seal.

Because removing the stopper breaks the internal vacuum and disrupts the system, remove the stopper to check water level no more frequently than necessary. Do not let the reservoir run dry. Always use clean water when filling and avoid getting debris or soil into the reservoir. Fertilize with Planter Technology's HM-10 Time Release Fertilizer for Sub-Irrigation systems, or with other water-soluble fertilizer. When using other fertilizers, use only water-soluble fertilizers at 1/4 strength recommended by manufacturer. Introduce directly into reservoir.

Do not put any systemic pesticides into the reservoir. Granular systemic may be incorporated into the soil area. Only use according to your state and local laws.

After a week the topsoil of the planter liner should appear dry (its normal state). If the topsoil is wet, repack the soil firmly, and don't fill the reservoir. Avoid removing stopper to check on water level any more than absolutely necessary.

Troubleshooting

The properly functioning Coronado Box will have dry topsoil. Soil 2-4" below the surface will be moist, but not wet.

Signs of Overwatering (a more common problem): Topsoil is wet or damp to the touch, or the unit continues to weep after 24-36 hours. Removing the stopper to check water level more often than necessary may lead to overwatering. To fix, repack soil solidly, adding additional soil if necessary. Plant sensor slightly deeper, making sure that the sensor is firmly packed in soil. Check that stopper is securely in the fill hole. Allow soil to dry out until the topsoil is dry to the touch before refilling reservoir.

Signs of Underwatering (a less common occurrence): Reservoir level remains unchanged between fillings. Look for signs of water stress, and test moisture level at least 2" below topsoil for moisture (the plant may not have needed water). Remove stopper, watch approx. 3-5 min. to see if water level drops. If it does, system is functioning. Top water lightly. If level does not drop, top water plants and wait another week. Remove stopper again, observe water level. If water still does not drop, inlet holes at bottom of planter may be clogged, and will require removal of plants to open.

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