When Planting Beneath Trees Mimic Their Need for Water

Q. I have two very old Olive trees and I would like to plant some greenery around the extensive roots at the base of the trees. Something low to the ground.

Plant at the base of olive trees but mimic their need for water and root depth.

A. There are many plants to pick from so let me give you the guiding principles when making a choice. Olive trees are Mediterranean in their climate preference. They like hot dry weather but are not desert trees. Technically they are classified as mesic (nondesert) in their water use, not xeric (desert). They can handle desert landscapes well but are not desert trees like Mesquite or Palo Verde.

Dwarf oleeander is Mediterranean in its water use and would be a good pick for planting beneath olive.

            Secondly, olive trees are irrigated to a depth of 18–24 inches deep. The watering area of older trees should extend from 2 to 3 feet from the trunk out to a distance nearly equal to the spread of its canopy.

            When selecting plants to grow beneath an olive tree, try to mimic these two features as much as possible. Selecting small flowers to grow beneath them requires frequent irrigation which olive trees will not like. Selecting larger desert shrubs (xeric) may cause these shrubs to grow excessively because of the more frequent watering needed by the olive.

            Some smaller, Mediterranean, deep rooted shrubs include petite oleander, Cistus (sometimes called Rockrose), dwarf myrtle, Euphorbias, rosemary (and other large perennial herbs), and even roses! Because these are Mediterranean plants I would use woodchips or decorative would mulch and not rock.

             I would look for a small to medium sized Mediterranean flowering shrub or groundcover since olive is also Mediterranean that thrives with a similar irrigation. Both plants will benefit from their close companionship.