Stone is the most durable, long lasting and strongest building material available. There are countless stone relics from thousands of years ago that are still standing to this day. To enjoy this same durability in the garden, consider creating a stone tree planter.
Measure the area where the planter will be placed. For a tree planter, it is recommended that the planter be at least 3 by 3 feet square or have a radius of 1 1/2 feet if round.
Mark out the area with chalk to guide where the stones will sit.
Dig a 12-inch wide and 8-inch-deep trench just behind the chalk outline for the planter's foundation. Fill the hole with large feldstones placed as closely together as possible.
Pound the feldstones firmly into the ground with a 4-by-4 piece of wood. This will ensure that the foundation is sturdy enough to hold the weight of the feldstone planter.
Lay the second level of stones on top of the first. Use the longest flattest stones possible for the corners. Avoid using mortar on the first five layers to provide drainage for water.
Set up a string representing the top of the planter after the first few layers are in place. Attach the string to the wooden stakes and wrap it tightly around. Verify that the string is level by hanging a line level in the center of each side.
Mix up a single batch of mortar in the wheel barrel. Place the mortar on the back half of the stones. This creates a more natural look.
Continue stacking the stones and laying mortar in between each layer. Reserve the flattest, largest stones for the top layer of the bed.
Fill the mortar bag with mortar and squeeze the mortar into the joints of the top wall layer. Smooth over the mortar with a putty knife.
Allow the mortar to dry overnight and apply a layer of masonry sealer in the morning using a spray bottle.