Care, Mulching & Circumference of Royal Palm Trees

Basic Care

• Plant royal palms in a sunny location in the landscape. This palm is intolerant of shade, and the cooler temperatures in the shade slow the growth rate and contribute to smaller, scrawnier fronds. Royal palm needs a regular supply of water but doesn't require soggy soil conditions. Fertilize the palm with granular, slow-release fertilizer at least three times a year -- very late winter, mid-spring and mid- to late summer. A light fourth fertilization in early to mid-fall helps with winter hardiness, especially if the fertilizer formula is a bit richer in potassium than usual. The large, heavy fronds naturally shed from the canopy, crushing whatever rests below. They are slow to decompose and difficult to move.

The Role of Mulch

• Across its native range, royal palms usually grow in deep sandy soils or shallow humus beds atop limestone. Few nutrients persist in these soils, so maintaining a 3- to 4-inch layer of organic mulch serves many benefits. As the mulch and/or compost decomposes, it provides minerals for root absorption. Mulch prevents weeds, including stopping fallen royal palm seeds from germinating wildly, conserves moisture and prevents the soil from getting too hot in the summer. Royal palms will manage to grow and prosper in limestone if watered well and a copious layer of mulch remains to sustain the roots, according to "An Encyclopedia of Cultivated Palms." Royal palm roots extend 10 to 30 feet beyond the reach of the frond tips.

Size and Habit

• When small and young, the royal palm looks slender and non-imposing. The trunk base is wide but tapers upward like an inverted carrot to support four to seven green fronds that look feather-like. With rich soil, heat and ample moisture, the royal palm skyrockets upward, maturing 60 to 100 feet in height. As it ages the trunk is no longer tapering, but a whitish gray column that resembles a concrete pylon. A mature royal palm has a huge crown of fronds, as many as 15 that radiate and gracefully droop from the growing tip called a crownshaft. The leaves individually measure up to 12 feet long filled with ribbon-like leaflets 2 to 4 feet long.

Circumference

• The diameter of the canopy atop a royal palm trunk can measure 25 feet wide, creating a circumference of 75 to 80 feet. This massive, heavy canopy is supported by a solid, muscular trunk that is between 1 and 2 feet wide. The trunk's circumference, with that diameter range, may measure between 3.14 and 6.28 feet around approximately 3 feet up from the ground. Palms stressed by years of drought or nutrient-poor soils do not develop such plump, robust trunks.