In 2006, The Arbor Day Foundation released an updated version of the USDA's Hardiness Zone Map that reflects the warming trends that have taken place over the past 15 years. Today, those who live in southernmost Nebraska are finding that they can plant more varieties of moderately cold hardy plants, like the magnolia. However for those in northern Nebraska, where winters can sometimes become unpredictably cold, there are plenty of cold hardy Magnolias. The Star, Leonard Messel, Merrill and Cucumber Tree magnolias can all survive up to hardiness zone 4.
Water your magnolia tree. In general, magnolia trees need 1 inch of water per week distributed over their root zone. However, check your magnolia's soil regularly. Water the tree when the soil is dry to a depth of 2 to 3 inches. Stop watering your magnolia tree when the ground freezes.
Fertilize your magnolia tree in spring and fall. Use a granular, slow-release 8-8-8 or 10-10-10 fertilizer. Spread 2 cups of fertilizer per 100 feet over an area that is three times the circumference of the canopy of the tree.
Leave the magnolia's blossom and leaf litter in place. In the wild, this decomposing matter fertilizes the tree.
Protect your magnolia when temperatures fall below -20 degrees Fahrenheit for an extended period of time. Hammer four wooden stakes (as tall as your magnolia) around the tree. Then drape a burlap covering over the tree and secure the edges with bricks or stones.
Prune your magnolia sparingly. Magnolias are meant to grow unfettered. However, you should prune any branches that cross, any water shoots that grow out of the trunk of the tree and any dead or damaged branches.