Royal palm trees are popular in many warm, coastal landscapes, particularly in southern Florida and parts of California. Considered the aristocrat of palm trees, the tree earns its regal name with its stately presence in the landscape.
Cuban royal palms (Roystonea regia), native to Cuba, are the species most commonly grown and found in landscapes. However, the Florida royal palm (Roystonea elata) is native to the state and grows in wild, swamp areas.
The major difference between the two royal palm trees is the Florida royal palm doesn't have the distinctive swollen trunk like the Cuban variety. The Florida has a straight trunk without any bulges along it. However, the bark of both trees would look similar up close. Other than that, it's hard to tell the two trees apart. Both types are hardy in USDA zones 10 and 11.
Additional characteristics to look for include:
- Royal palm trees can grow to 125 feet tall at maturity, growing at a rate of around a foot yearly.
- Evergreen fronds average 10 feet long with pinnate, green leaves that are 8-inches long.
- There are 15 to 20 fronds making up the canopy or crown of the palm.
- Older portions of the trunk is rough and gray, with the immature section at the top of the tree a smooth, bright green.
- Fragrant, yellow flowers bloom on 3- to 4-foot stalks in summer, followed by purple to black, half-inch fruits that aren't edible.
Royal palms are relatively hardy trees, provided they grow in desired conditions and their preferred climate.
Consider the tree's size at maturity when selecting a site in the landscape. Situate the royal palm away from utility lines or the house, giving it room to grow without interference. The grace and beauty of the royal palm make it a popular choice used along streets, large parking lots, or in medians along the highway.
Another difference between the Cuban and Florida royal palm is the Florida species handles wetter soil conditions better than the Cuban type, which handles drought conditions better. Newly planted palms require a deep weekly watering until the tree establishes its root system about three months later. Established palms require water every two to three weeks, especially when conditions are hot and dry.
Royal palms tolerate a wide variety of light conditions from full sun to partially shady.
Preferred Soil Conditions
Soil can be clay, sand or loam; it doesn't seem to be very picky in this regard as long as it drains well. The Royal palm prefers acidic to slightly alkaline soil, but be careful not to have too much alkalinity or the fronds may come out frizzled. Planting in soils with a pH of 7.5 or less promotes the best growth.
The palm tree tolerates short periods of cold as low as 28 degrees Fahrenheit. Gardeners living in USDA zone 9B where freezes aren't common can also have success growing royal palms, though if a hard freeze occurs, be prepared for your tree to suffer some damage.
Regularly feeding your royal palm cuts down on the possibility of the tree suffering a nutritional problem. It's best to feed the palm tree every three months, using 1.5-pounds for every 100-square feet of the tree's canopy. Use a slow-release product with an analysis of 8-2-12 and spread evenly under the palm's canopy. Do not let the product butt against the trunk or burning occurs. Scratch the fertilizer into the soil and always make sure to water the product into the ground after applying.
If planting a new royal palm, do not fertilize at the time of planting or you can burn the roots. Wait approximately eight to 12 weeks before applying the first round of fertilizer.
One good thing about royal palms is they are self-cleaning, meaning the old fronds naturally drop from the tree without the need for pruning. As with all palm trees, it's not advised to remove fronds that are still green because the tree is still receiving nutrients from them.
Finding Royal Palms
Since royal palms are hardy only in the warmest climates of the U.S., you have the best chance of finding one at nurseries within its hardiness range. However, there are several online companies that sell the palm tree. Jungle Music and Real Palm Trees.com sell royal palms in sizes ranging from 2-gallon containers all the way to trees over 30-feet tall, but expect to pay a hefty price for this palm, as it's one of the more expensive palms on the market.
You can also inquire at your local nursery. If they do not carry them, they may know who does in your area.
Planting the Palm
There's no need to amend the planting site with amendments or fertilizer and adding fertilizer to the planting hole will burn the root system. It's best to just plant in the native soil.
- Clear a planting site that is at least 3 feet in diameter of all vegetative growth. Unwanted vegetation robs much needed nutrients and water from the root system. Keep the area free of weeds and grasses.
- Dig a hole that is slightly wider and deeper than the royal palm's root ball or the container it's growing in. This helps loosed the soil making it easier for the roots to spread out.
- Remove the palm from its container or if the root ball is covered in burlap, remove the burlap.
- Set the root ball into the hole, straightening the palm so it sits straight.
- Backfill the hole halfway with soil and water the hole to help settle the soil and remove any pockets of air.
- Finish filling the hole with soil and tamp it down around the trunk's base using your foot.
- Water the planting site again, using enough to saturate the root ball. Continue irrigating weekly for at least eight weeks while the roots become established in the new site.
Royal Palm Problems
The Royal palm is resistant to many pests and diseases; however there are a few that you should be aware of.
Royal Palm Bug
The royal palm bug (Xylastodoris luteolus) occasionally causes cosmetic damage to royal palm trees and rarely kills the tree. The insect infects older and established royal palms, rarely infesting trees smaller than 3-feet. Infestation is most problematic during spring but usually cures itself during the hot months of summer and the pest infects new leaves just as they begin to unfold.
The insect is around 1/10-inch long, has a flattened oval body that is greenish-yellow with reddish eyes. Royal palm bugs suck the sap out of the palm's fronds leaving a brown tattered look to the leaf. First signs of an insect problem arise as yellow specks on the frond.
Royal palms infested with the royal palm bug rarely need control. Spraying the tree isn't advised due to the tree's height and difficulty in reaching the canopy and drift. Gardeners can use a soil drench containing Imidacloprid to treat the problem. Remove any vegetative growth around the tree's base and use 1-ounce of the product for every inch of the royal palm's trunk
Palm Leaf Skeletonizer
The palm leaf skeletonizer is a smallish brownish-gray moth that lays its larvae on the undersides of older royal palm leaves. This insect is problematic in the southeastern states. The caterpillars eat both the upper and under surface of the palm's leaves between the veins or ribs leaving a skeleton-like surface to the foliage, thus the name. Eventually, the entire frond dies.
Signs of a palm leaf skeletonizer infestation are brown sawdust-looking fecal matter covering the fronds. If you brush away the brown substance, you should see the small, whitish caterpillars feeding.
Gardeners have several options to controlling the problem. You can wash the infected area of the palm with a damp cloth, or blast the caterpillars from the frond with a strong blast of water. Removing the infected frond and discarding in a plastic bag keeps the insects from moving on to another palm frond. Spraying the royal palm's fronds with a product containing bifenthrin also helps control the caterpillars.
Ganoderma Butt Rot
Ganoderma butt rot, caused by the fungus (Ganoderma zonatum) will kill infected royal palms and by the time symptoms are visible, the tree has already been rotted on the inside. Researchers still don't understand what conditions promote the disease, but all types of palm trees are susceptible to the problem.
First signs of ganoderma butt rot is a conk forming on the lower base of the royal palm's trunk. The conk releases the fungi into the palm and infects the root system. Due to the size of a royal palm, it's advised to remove the tree from the landscape as soon as you notice the conk, or the tree will eventually fall over and possibly damage a structure. No treatment is available and removal of the tree is the only option.
If you are looking for a palm tree that instantly dresses up your landscape as a tropical specimen, then look no further than the royal palm. You will be the envy of the neighborhood with the addition of this majestic palm.