How to Propagate Palo Verde Trees
by Stephan Sawyer, Demand Media
As natural desert growers, palo verde trees are very tolerant to bad soil.
Blue palo verde (Parkinsonia florida) and little leaf palo verde (Parkinsonia microphylla) are the two palo verde species which are not invasive and are native to the southwestern United States and southern California. These highly drought tolerant trees remain sparse for much of the year but create a brilliant bloom of yellow to yellowish green flowers in the spring and summer. The blue palo verde in particular creates a fine yellow spring and summer bloom. Both types of palo verde are hardy in Sunset’s Climate Zones 8 to 14 and 18 to 20. Propagating either blue palo verde or the little leaf species, which are nearly identical in nature, starts with the seed pods that usually drop during the fall and early winter.
Collect as many of the seed pods as you need from below either little leaf or blue palo verde trees after they have dropped during the late summer, fall or winter — fruiting times can vary for these trees.
Cut open the seed pods with a pair of strong scissors or branch clippers and remove the small bean-sized seeds from within. The seeds will have a very tough outer shell and you will need to either nick open a small hole with a sharp knife or sand down one corner of each seed with a file until the outer skin is thin. Otherwise, the seeds may not sprout.
Place your seeds in a pot of warm water and soak them for 24 hours. This is to soften them up and cause them to swell slightly, making successful propagation more likely.
Plant your seeds in small planters filled with well-draining soil that is at least 30 percent sand or some other substrate, like fine gravel, that drains well; 30 percent is a good minimum for proper drainage. Keep them at a constant 70 degrees Fahrenheit and the soil moist at all times until they have sprouted, which should be within two months or less.
Transplant your sprouted seeds to a garden bed with well-draining soil. Keep in mind that little leaf palo verde can reach heights of 20 feet and blue palo verde can grow as tall as 50 feet, so separate your seedlings at least 25 feet apart. Palo verde is extremely good at growing in nearly any type of soil, so aside from the soil being sandy enough to drain well, you won’t have to worry about its pH or fertilize. However, when planting the sprouts, water the surrounding soil until it is soaked to a depth of several inches. If your soil is lacking in drainage, add a 3- to 5-inch layer of sand or pea gravel over the top of the planting area and work it in thoroughly with a hoe or rototiller to a depth of 8 to 12 inches.
Water your young plants regularly until they have established themselves. This may take as many as two years or more. Once planted, water your young plants once a week until the surrounding ground is soaked. After their first summer, water them deeply once a month during the fall and winter; during their second summer, water once every two to four weeks.