Q: About four to five years ago, I planted an oak tree in my front yard. ... As yet, it has not grown, I donβt think, 1 inch. It does get leaves every year, but thatβs it. What can I do to help it grow?
A:Β Trees transplanted to a new location typically take a couple years to adjust to their new surroundings. A big part of the adjustment is growing new roots, which are usually drastically pruned and damaged in the transplanting process. Since the below-ground root growth is not obvious to us above-ground animals, it appears that nothing is happening for quite a while. The rule of thumb is: The first year they sleep, the second year they creep, and the third year they leap. This growth pattern assumes the tree was planted in a suitable location and the care was appropriate. Care, once established, includes annual fertilization with a complete fertilizer and regular irrigation. For an oak tree that is not a native desert species that means watering to a depth of 24 to 36 inches every seven to 14 days in the summer, every 10 to 14 days in the spring and fall, and every 14 to 21 days in the winter. The emitters for your drip irrigation system should be placed in a ring around the tree at or near the edge of the tree canopy so the water will reach the absorbing roots. You can also put a half-inch of compost on top of the soil around the tree root zone and an inch or two of organic mulch on top of the compost. The slow release of nutrients from these as they decompose, along with their protection of the root zone, can help keep your tree healthy.
Peter L. Warren is the urban horticulture agent for the Pima County Cooperative Extension and the University of Arizona. Questions may be emailed to tucsongardensage@gmail.com