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Ask Dr. Hort: Don't plant live oak too deep


SCOTT KEELER | Times (2009)


Live oak may not be able to breathe

Q: I purchased a 14- to 16-foot live oak from a reputable nursery. It was healthy, with dark green leaves, when planted on July 31, 2009. It was watered every day for two to three weeks, then every other day for a couple of weeks, then once a week for two weeks. I used one bag of manure and one bag of planting or potting soil, and the rest was the original dirt dug from the hole. The area is on a slight slope, so there is excellent drainage.

For about a month, it maintained its leaves, then slowly lost them all. For a month or so, it was bare. By mid September, it replaced all of its leaves with new, dark green leaves.

Then we had an early cold snap late in September, and shortly afterward, it lost all leaves again. Between October and late February, the tree has had no leaves. Should a live oak lose all its leaves in winter? Is it dead? I gave it a "scratch" test the other day. Lower branches reveal no noticeable green below the skin. Some upper branches show some green underneath, but not much.

Mark Hodgin, Palm Harbor

A: You may have killed it with kindness. It appears that the tree was planted too low. I am assuming that you mixed the manure and potting soil with the existing soil, which made it light and fluffy. When planted, the tree sunk down in the hole, cutting off the oxygen supply to the root system. This was enough stress to cause the leaves to fall off of the tree. Also the additions to the planting hole would suck up water, probably too much. Current research shows the best method is no additions to the planting hole, a hard bottom to the hole, and planting the tree 3 inches above the existing soil surface, with mulch spread from the lip of the root-ball back a couple of feet. Scrape soil away from the trunk and see how deep the top "surface" roots are located. A few inches makes all the difference.

Crotons brown from cold? Cut them back to green wood

Q: My crotons froze about a month ago. About 80 percent of each plant has brown leaves. The plants are not dead. How should I treat them? Fertilize? Trim? Thanks for your help.

Ky Koch

A: Go ahead and cut back to green wood, scratching with your fingernail to find it. By now, little green buds should be sprouting, another guide on where to cut back to. Fertilize with a slow release fertilizer, 8-2-12 or similar, to wake the crotons up for spring.

Camphor isn't good for keeping warm

Q: Is it harmful to burn camphor tree logs in one's fireplace?

John Mullins, Seminole

A: It's probably not a good idea. The smoke is considered toxic and all of the compounds that make up the camphor oil can put one whale of a coating in your chimney!

Your city might offer free organic mulch

Now that pruning and fertilizing are in full swing, it's time to mulch. Use organic mulches, such as recycled yard waste, which is free from some municipalities if you pick it up, or you can have it delivered for a small fee. (Check with your city offices.) You also can use bagged mulches like pine bark nuggets or melaleuca (stay away from cypress if possible to be environmentally responsible). Spread mulches 2 to 3 inches deep, but deeper is not better! Keep mulch away from the base of plants to prevent disease.

Need help?

Enter Greg "Dr. Hort" Charles, who for more than 30 years educated gardeners through the Pinellas Technical Education Centers. He answers questions about landscape and garden pests. E-mail your questions to or to (put Dr. Hort in the subject line). Mail questions to HomeLink, Features Department, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731. Describe your problem in full, and include your name and contact information. If possible, include a photo. We will print his advice on Saturdays in HomeLink.

Ask Dr. Hort: Don't plant live oak too deep 03/12/10 [Last modified: Friday, March 12, 2010 3:30am]
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