Ask Mr. Smarty Plants

You probably answered your own question when you said (on September 13) that you had planted the tree 2 weeks ago, which would have put the planting on about the first of September. We understand that it's cooler in Nebraska than it is in Texas, but summer is not the time to plant a woody plant anywhere. The tree is probably suffering from transplant shock; in Thayer County, we would imagine it is recommended that you plant woody plants in early Spring, after (hopefully) the last frost, while the tree is still semi-dormant. However, you also shouldn't buy one and hold it in the pot for that many months so, having bought it, you did right to get it in the ground right away.

We'll tell you what we know about your plant and see if we can help you keep it alive. Magnolia stellata is native to Japan. The name 'Royal Star' is no doubt a trade name given to the tree for additional sales appeal. The Lady Bird Johnson Wildflower Center is dedicated to the growth, protection and propagation of plants native not only to North America but to the area in which the plants are being grown, so your tree is really out of our range of expertise. There are several magnolias native to North America, but none are listed as growing in Nebraska. Your USDA Hardiness Zone is 5a to 5b, and the magnolia is hardy from Zones 4 to 8, so the temperature is not the main culprit. We don't know what your soils are, but the fact that none of the native magnolias are native to Nebraska is a clue. The magnolia likes moist, organic, fertile soil and full sun. It is prone to damage from heavy snow and ice.

We hope that, whatever your soil, you dug in some organic matter such as compost to amend the soil texture and make nutrients and water in the soil more accessible to the tiny rootlets on the tree. If not, at least add compost or shredded hardwood mulch to the surface soil. This will not only protect the roots from heat and cold but, as it decomposes, it will improve the texture of the soil. Beyond that, your best bet is to insert a hose as deep into the soil around the roots as you can push it, and let it dribble slowly, until water reaches the surface. If the water remains on the surface more than 30 minutes instead of soaking in, you probably have clay soil, which magnolias don't like but will tolerate. The best treatment for a clay soil is, again, organic material in the soil, which helps with good drainage. As long as it is still hot and especially if you are not getting regular rains, repeat the "dribble" treatment at least twice a week.

After that, the best you can do is protect the roots with mulch and wait for Spring. If it doesn't leaf out in the Spring, it's a goner. Sorry.

See this Washington State University County Extension article on Magnolia Stellata 'Royal Star.'

Pictures of Magnolia stellata 'Royal Star' from Google.