From Gardener's Supply (

Instructions for the Self-Watering Metal Windowbox


The Self-Watering Metal Windowbox includes the following parts:

  • Planter
  • Perforated Tray
  • Water Fill Sleeve
  • Brackets

The windowbox parts have sharp edges; we recommend wearing gloves during assembly.

1. Place the Perforated Tray in the planter with the flat surface facing up.

2. Insert the Water Fill Sleeve into the slot provided in the side of the Perforated Tray. Do not remove the sleeve once the planter is filled with potting soil because soil could become trapped in the sleeve. If soil becomes trapped, remove and clean out the sleeve, then replace it.

3. Install the Brackets on a deck rail or under a window, using your own hardware. Be sure to use hardware that is appropriate for the wall material.


4. Prepare 12 quarts of planting mix (potting soil) by moistening it thoroughly. Mix in slow-release granular fertilizer. We recommend All-Purpose Fertilizer.

Pour a few inches of soil into the planter and press it firmly onto the Platform. Continue to fill the planter with soil to within 3″ of the top edge of the windowbox.

5. Add your plants.

6. Fill the Water Reservoir through the Water Fill Sleeve. Water is absorbed by the soil through evaporation, drawing moisture up through the Reservoir Platform.

Important: Check the water reservoir regularly, especially if you live in a hot, dry climate or experience extended periods of dry weather. If the soil dries out, refill the reservoir and water the soil directly to help re-establish the wicking action. An overflow port keeps plants from drowning during heavy rains.

Keep the soil moist but not soggy. If you find the soil is too wet, do not refill the water reservoir. Allow the soil to dry out a bit before you add water.

Last updated: 10/24/15