NO NEW GROWTH? Are your newly-installed plants not showing any signs of new growth? Look for planting problems. The biggest problems we have seen with landscape plantings are planting too deep and not watering the soil into the planting hole. Take your time when you are planting trees and shrubs in your landscape. Most people are in a hurry to get it done and just don’t follow some very simple planting procedures.
First, dig the hole deep enough so that you have to put amended soil back into the hole to get the plant raised to the right depth. If the hole is “just barely deep enough” and you stop because the digging is difficult, then you will have difficulty with that plant for the rest of its, or your, life. Amend the soil taken out of the hole to be appropriate for the plant. This is the same soil used in the planting hole. If you have questions, ask your nursery professional.
Remove the plant from the container. Don’t pull the plant out of the container by its stem. Turn the container over into your hand and gently pull the container off of the root ball. You must work quickly now.
Place the root ball into the hole and gently dislodge some of the roots on the edge of the ball, being careful not to break the ball. Begin adding the amended soil to the hole and adding water from the hose in a slurry to settle the soil around the root ball. You should see air bubbles in the slurry.
Use your shovel or hand trowel to encourage the soil to settle, removing air from the planting hole. The soil in the planting hole should be added until it reaches the top of the root ball. When planted correctly, the shrub or tree should remain anchored in the planting hole when the top is moved from side to side as if blowing in the wind. If it isn’t, then replant it.
Construct a circular dike around the planting hole two to three inches high and water it in with a hose. The dike can be removed later if they are irrigated using drip.
IRRIGATION PROBLEMS? Irrigation problems are the No. 1 reason for brown lawn spots. The irrigation system must be designed, installed and maintained properly. Irrigation sprinkler heads must have head-to-head coverage (water from sprinkler heads should overlap enough to reach neighboring heads in the vicinity). This is a necessity.
Sprinkler heads should have nozzles that are all the same type, not a mixture of several types on the same system. Each sprinkler head should have the same nozzle so that they put the same amount of water down on the lawn during an irrigation cycle. Mix and match heads may not do this. Mix and match heads in a lawn will waste water and affect your water bill. Reducing water use to dry up swampy parts of the lawn will result in brown areas in other parts.
Grass responds to a lack of water by first turning gray-green or smoky-colored. If a lack of water persists, the area turns brown. If not watered, eventually the entire grass blade and the plant will turn brown. This results in brown spots that get larger as long as the water is not available. A few days after rewatering, the grass blade tips remain brown while the base of the leaf blade is green.
Brown spots resulting from a lack of water, and then rewatered to bring it back to life, are easy to detect. Grass blades near the brown areas will have a brown dieback on the tips. If the grass blades surrounding the brown area do not have this brown dieback, the problem is probably not related to a lack of water.
Usually brown spots resulting from a lack of watering will have a distinct location in the lawn. They will be located generally in the same spots in a lawn in relation to the sprinkler heads.
Another reason for brown spots due to watering, and not mentioned very often, is from excess pressure in the irrigation lines leading to the sprinklers. Some areas of the valley have a lot more water pressure in other areas. Lawn watering systems are designed to operate within certain pressure limits. If this pressure is excessive, water from the sprinkler heads comes out under extreme pressure.
This results in a spray of water known as “fogging.” You can see it easily of you watch the water coming from the sprinklers. This fogging results in a mist that will move with the most gentle of winds. Since irrigation systems are designed to work best under a very narrow range of pressures, water is applied unevenly to the lawn when pressure is excessive.
The best way to handle this is to install, or have installed, a pressure regulator on the irrigation system. This will keep excessive pressures under control but not affect the system if water pressure is insufficient.
The author is part of the University of Nevada, Las Vegas, Cooperative Extension.