Tree Planting Requires Proper Hole Preparation in the Desert

Q. I had a boxed mastic tree planted recently. I didn’t like how it was planted. It was planted with the trunk not straight, the top of the roots exposed, the soil in the hole was dry, and I had them remove the bottom of the box. They were going to plant it with the bottom of the box still under the root ball.

Mastic tree planted too shallow. Also the area is very small for such a large tree.

A. I looked at the pictures you sent to me, and I agree it was not planted well. Sloppy planting. The hole was dug too small, and it was not planted deep enough. About 30% of the soil should be amended for drainage and moisture retention. Out of sight, out of mind. The soil surrounding your tree may or may not have enough amendments added.

Watch this video on planting trees in Arizona that I thought was pretty good.

Mastic (Pistacia lentiscus) trunk was planted with the trunk at an angle which is less of a problem than the exposed rootball (above).

            Mastic is related to pistache (Pistacia lentiscus). Like all pistache trees, it is mesic in its need for water. This tree is Mediterranean in origin rather than western Chinese or Central Asian. Water requirements for both are similar and both develop red fall color. It grows well in a lawn where it gets plenty of water or surrounded by other mesic shrubs for the same reason.

            When planting on a slope, the lowest side of the hole should be used for judging the hole depth. Add water at the top and sides of the hole, not the bottom. This tree is fine growing in soil covered in rock. If this tree shows signs of poor growth in a few years, add a layer of compost on top of the soil and water it in. Water should be applied on the “uphill” side of the tree but three feet at least from the foundation of the house.

Dry Hole Problems

            The problem planting in a “dry hole” is removal of air pockets. Dry soil pushed into the rootball (and using the butt end of a shovel to shove it further) may or may not remove them. Usually not. When planting in a slurry of soil the air pockets are removed at planting time (look for the bubbles), less “transplant shock”, and less concern about tree stability (staking) after planting. Air pockets in the soil will not do that.

Wet the Soil

            Making a slurry is easy to do. Just use a hose during planting. Sometimes a dry soil can be compensated in the first few months by circling a moist rootball with a “moat” or donut on top of the rootball when planting and wetting the soil after planting. Either that or apply water slowly or several times to get it to soak in.

            This tree grows about 25 feet tall with about the same spread when fully mature. Pay attention to branch direction and the house when planting. Dig the planting hole at least three times the width of the plant container. Amend the soil removed from the planting hole with “organics” of some sort to keep the soil loose, friable, and well drained after planting.

How Close to the Home?

            I wouldn’t plant it any closer than 8 to 10 feet from a house to accommodate the watering and branch growth. Trees should be planted as close to vertical as possible. When trees are planted from a wooden box, usually the bottom of the box is removed first, and the sides are removed after lowering it into the hole. Fill the hole half full and then ADD water to make a slurry. Never add dry or hot soil to a planting hole.