Xtremehorticulture

Trees Planted in Grass Need Extra Water


Q. I had a 3 year old mesquite tree in my front yard that just blew
over in the wind today.The original landscapers planted a tree without a drip
system. I have an area of grass around the tree and they told me in the past
that that is sufficient to water a tree. Today the landscapers that came to cut
down the tree told me it fell because of the roots being at the surface. Do you
recommend putting in the drip line? I can tell you the soil under the tree was
very moist from the sprinklers. I have attached a picture of the felled tree. Any
suggestions for a tree that would be sturdy to the wind? The original tree
planted was a glossy privet that died after the first year. It was replaced by
the mesquite. I have to plant something in the 24 inch box size per HOA rules.
Mesquite tree that blew over

A. I am sorry to hear about your tree that blew over.
This can be a problem sometimes with trees that are planted in or near lawns
and rely only on lawn irrigation. Lawns require shallow irrigation that are
frequent. Trees and large shrubs require a larger amount of water applied less
often. Be very careful of planting trees that originate from deserts and used
for desert landscaping (examples are acacia and palo verde) planted in the
lawn. This usually does not work well. Trees that are suited for lawn areas are
those that are not desert trees.


Trees and large shrubs getting water only from the lawn
will fight for the shallow irrigations of the lawn. If you are an efficient
lawn irrigator, the tree will have a difficult time getting the deep
irrigations it needs for deep rooting. When trees are planted in large
turfgrass areas, such as golf courses or parks, the trees always grow faster
and perform better if they are supplemented with water for the first few years.
After three or four years of successful growth, you could eliminate the hose
irrigations around the trees except perhaps during the hottest parts of the
summer.

Mesquite roots can good deep if given a chance. This is a native mesquite in Zacatecas, Mexico, near a river. The roots had found moisture from the river but not at the surface and so were forced to go deep where moist soil was located.

Some golf course superintendents would send out a water
truck once every week or two to flood the area around the tree with water. This
encouraged deeper rooting and kept the lawn from robbing the tree of its
shallow water supply.


You can do the same thing with a hose. When a tree is
planted in the lawn area it is best to leave a shallow depression around the
tree 3 to 4 feet in diameter. This can be a basin for flooding the area around
the tree every week or two with a hose. It also helps, as you have done, to
keep that area free of grass and weeds. If you can remember to water with a hose,
particularly during the heat of the summer, you can save yourself the expense
of installing a new drip line.

Mesquite trees are what we call riparian tree species.
Unlike Palo Verde or acacia in the desert, Mesquites are only found near
waterways. They grow when water is available and stop growing when water is
not. When water is constantly available, they constantly grow. When Mesquites
get water they can grow quite rapidly, as much as 8 feet in a single year. 
Honey mesquite with mistletoe in the Mojave Desert in North Las Vegas
This
is a problem when they receive constant watering because their tops grow faster
than their roots and this contributes to blow over. For this reason Mesquites
are not a good choice for a lawn area but are more appropriate for a desert
landscape. In lawn areas stay away from desert trees. Trees like many ash,
Locust, honey locust, privets, and others are not desert trees and they will
survive in the lawn much better.
Personally, I think you are better off without the lawn
unless you have a use for it. You can substitute green groundcovers and achieve
a similar look to a lawn. When you plant trees and you do not have a lawn make
sure that you surround the trees with some smaller shrubs to help keep the
trees irrigated. Focus on smaller trees that are in scale to your home. Don’t
put in 40 foot trees if you have a single story home. 
Take advantage of the
shade they give and put them so they shade the south and west walls and provide
shade to where you have outside activities. Trees should probably not be
planted just for looks in the desert. They should also have something to
contribute to your comfort as well. So remember to keep your trees small, use
desert adapted trees whenever possible, minimize the use of tall trees and shrubs
to reduce your water use and to make sure they contribute to your home
environment and your outside living environment.

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