Prepare your planting location by loosening the soil to a 12-inch depth with a pitchfork or garden spade. Test the soil after loosening using a soil pH testing kit.
Amend the soil before planting the agave if the soil test reveals a pH outside the 6.5 to 7.0 range. Add lime to the soil for a pH below 6.5 or peat moss for soil with a pH above 7.0. Mix the required amendment in with the soil according to the packaging directions.
Dig a planting hole for the agave cactus twice the width of its growing container. Dig the hole only as deep as the agave's growing container. Slide the agave cactus out of the growing container once the hole is ready.
Set the agave in the center of the planting hole with the foliage above the soil line. If any foliage is below the soil line, add soil to the bottom of the hole to raise the plant. Backfill the hole, patting it around the stem of the agave cactus to remove air pockets.
Water the agave deeply after planting using a garden hose. Dampen the soil to a depth of 1 inch. Maintain moist but not soaked soil after planting. Most succulents appreciate deep, biweekly waterings when the top layer of soil begins to dry out.