Garden urns add a decorative element to you outdoor design. Available in a range of sizes and designs, urns are usually narrow and tall. They may consist of an open planter sitting atop a column or base, or they may resemble a large flower vase that may or may not have a narrow waist and a large opening and bottom section. Many urns do not have drainage holes, so preparation is necessary before planting. As most plants only send down roots 6 to 10 inches into the soil, the urn may also be unnecessarily deep.
Fill urns that are deeper than 12 inches with a filler material. Use crushed plastic bottles, cans or foam pellets and pieces. Fill the urn up to within 12 inches of the rim with these materials.
Place a planter insert into the urn if it does not have pre-drilled drainage holes in it. Use a planter insert with at least one drainage hole, or substitute a plastic planter that is one size smaller in diameter than the diameter of the urn.
Fill the urn or insert to within 1 inch of the rim with lightweight potting soil. Water the soil until the excess liquid drains from the bottom, moistening the soil throughout its depth.
Plant bedding plants or flowers in the soil at the same depth they were at in their nursery pots. Space the plants at a distance half that recommended on the plant label. Set taller plants in the center of the urn and shorter plants around rim to provide a nice mounded appearance.
Check the soil moisture in the urn daily and water the plants when the top 1 inch of soil begins to feel dry. Water the plants once a week with half-strength soluble plant fertilizer instead of clear water.