What Causes a Queen Palm Tree to Turn Yellow?

Queen palm (Syagrus romanzoffiana) earns its royal name because it makes a stately landscape specimen. The tree grows in U.S. Department of Agriculture plant hardiness zones 9 through 11. Grown in preferred conditions and with required nutrients, queen palm fronds are green, with no signs of yellowing. When conditions are undesirable, yellow fronds occur. Nutrient deficiencies may be to blame, and left untreated, these problems may lead to the palm's death.

Healthy, mature queen palms grow as tall as 50 feet. The single-trunk tree grows upright, with a smooth, grayish trunk. The canopy grows as large as 25 feet in diameter. Fronds are green, feathery and the leaf blades grow as long as 36 inches. Throughout summer, large stalks filled with cream-colored flowers form. After the flowers fade, the stalk fills with small, marble-sized dates. When ripe, the coloration changes to bright orange.

Queen palms prefer growing in full sun, but tolerate partial sun. The tree suffers the least amount of health problems, including yellowing fronds, when grown in various acidic, well-drained soils. It performs poorly when planted in constantly wet soils. The palm develops health problems, which result in yellowing fronds, when planted in alkaline soils. Foliage damage occurs when temperatures reach 25 degrees Fahrenheit, and temperatures of 20 degrees Fahrenheit kill the tree, according to Floridata. Maintain a weed- and grass-free area around the tree of approximately 3 feet in diameter. Bare soil allows nutrients to reach the queen palm's roots and eliminates yard equipment damage to the trunk.

Magnesium deficiency shows up as yellowing bottom fronds with the center rib of the frond remaining green. Once a queen palm's fronds yellow due to magnesium deficiency, it will not return to green upon treatment. Regular applications of magnesium sulfate, also known as Epsom salts, treats the condition. Apply four equally spaced applications of magnesium sulfate yearly, according to the University of Florida Collier Extension Service. Follow package instructions, considering the tree's size. Average application rates are between 2 and 4 lbs. for each treatment. Spread the product evenly under the palm's canopy and water it into the soil.

Queen palms deficient in potassium sometimes die. The symptoms show up on the bottom fronds as yellow or orange freckles. As the condition worsens, the colored freckles turn brown. The frond's foliage sometimes frizzles and eventually browns and dies. Gardeners should not prune fronds off the palm until they are completely brown and dead. Pruning off green or partially green queen palm fronds starves the tree of required nutrients it is still receiving, including potassium. Treat the condition by applying sulfur-coated potassium sulfate evenly under the canopy. Apply in four equally spaced applications each year. Use 3 to 8 lbs., depending on the palm's size. Following package directions concerning the correct amount. Apply an additional treatment of magnesium at the same time. Use one-third the amount of magnesium that you used for potassium.