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Thursday - April 27, 2006

From: Round Rock, TX
Region: Southwest
Topic: Trees
Title: Fertilizer and application for live oak trees
Answered by: Dean Garrett

QUESTION:

What do I use to feed live oak trees? How do I apply the fertilzer?

ANSWER:

A standard fertilizer should be fine. One landscaper I interviewed advised an 8-2-4 compost-based fertilizer, meaning 8% nitrogen, 2% phosphorus, and 4% potassium. Others weren't so specific as to proportions, saying only "standard" or "regular."

All my informants said that if the tree is a naturally occurring specimen that has survived on its own without human intervention and still looks good, nothing may be needed. However, if the tree is now surrounded by new construction that may have damaged its roots, a fertilizer with significant phosphorus for root growth will help it adjust. Significant phosphorus will also be needed if your tree is a newly planted purchase that you want to encourage to spread its roots beyond its root ball.

All said that surface applications are best. Spread the fertilizer from near, but not on, the trunk, to a foot past the extent of the leaves.

A couple of friends of mine have maintained beautiful live oaks for two decades with little more than compost applied two or three inches thick from near the base of the tree to just past the dripline.

A deep, slow, soaking watering just after you fertilize will insure that the nutrients get to the roots. Doing it just before a good rain is even better.

Whatever you use should be applied once or twice a year. The most important time to fertilize is in early spring, just before new foliage appears, to help fuel the new growth. Though considered evergreen, live oaks (Quercus fusiformis, Quercus virginiana, or hybrids between the two) actually lose all their leaves in early to mid-spring, but the new growth appears about the same time that the old leaves drop, so most trees never look bare.

A second application in early summer can help fortify the tree during the harsh Central Texas heat.
 

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