My Magnolia trees are losing their leaves

Question

I recently purchased three trees: two Ann Magnolias and one Jane Magnolia. I have since planted them in the ground in my front yard, using a bit of Osmocote when I did so.

The Ann Magnolia tags said they were full sun, so I planted them in an area where they would receive plenty of sunlight; the Jane Magnolia’s tag said it was part sun, so I planted that in an area where it would receive a good amount of sun and shade from a neighboring tree.

One of my Ann Magnolias, though still alive, seems to have gone dormant. Shortly after being put in the ground, its leaves slowly began to turn a murky brown color. It has since lost ALL of its leaves. I think it’s still alive, though. The other seems to be doing fine. They receive the same amount of sunlight, water, etc., so I wanted to know if there’s any explanation for one having lost its leaves, while the other looks so full and healthy.

My Jane Magnolia, though still full, seems to be starting to have a similar issue. Some of its leaves have begun to show some brown spots, similar to the ones that started to show up on my Ann Magnolia.

I think it’s important to note that I live in a Zone 10 area, just a few miles from a Zone 9, so perhaps it may just be the intense heat we have to tolerate down here? There have been no heavy rains, no temperatures above 100*F, no other factors I can think of. Aside from our rose bush leaves turning a bit yellow, and our avocado tree looking a bit gloomy, none of our other plants are exhibiting similar issues.

Any suggestions?

Thank you for your time, and I hope you have a wonderful day!

Answer 1

Keeping newly planted Magnolia Trees watered well is crucial to there success.
The soil should be nice and rich and can be amended with some compost.
Watering should be done deeply and the soil allowed to drain and dry out just slightly between waterings. The soil should never be soggy.
A good watering is laying the hose at the base of the tree and allowing it to trickle water for about 20 mins.
These deep waterings should be continued for the entire first year. It can take even up to 5 years for a Magnolia to become established.
Additional water during hot spells is important.

Use 2 to 3 inches of hardwood mulch around the base of the tree to help retain moisture. Pull the mulch away from touching the tree itself.

Though nearly all new plantings have some stress, I believe your trees are lacking water.

Make adjustments to water and watch for new growth.
Do not fertilizer until they are actively growing.

https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-care.htm