Selecting the Right Container for Revegetation Success with Tap-rooted and Deep-rooted Chaparral and Oak Species

Abstract

I report on previous research and the results of several multi-year projects that point to the effectiveness of using deep l-gallon container plantings rather than liner, 1-gallon or 15-gallon container plantings for habitat restoration of deep/tap-rooted species in xeriphytic Mediterranean climatic areas. I highlight two recent projects to demonstrate the higher survival and growth resulting from the use of deep 1-gallon plantings for three deep/taprooted species—lemonadeberry (Rhus integrifolia), laurel sumac (Malosma laurina), and California live oak (Quercus agrifolia)—when compared with liner and 15-gallon plantings. Less expensive chaparral shrub liner plantings are shown to produce low field survival rates that negate initial cost savings when compared with deep 1-gallon plantings. Oak seedlings grown in 15-gallon containers, while much taller at planting than deep l-gallon oak plantings, are shown to not justify their substantial additional production time and planting costs since deep 1-gallon plantings can surpass 15-gallon container growth rates in less than two years. While no long-term comparisons are made between standard and deep 1-gallon plantings of deep/tap-rooted species, I make a case for the greater likelihood of conventional 1-gallon tap-rooted plants developing detrimental root-binding under standard nursery growing conditions.