UT Gardens' Plant of the Month:
Scarlet Firethorn

by Dr. Sue Hamilton


Scarlet Firethorn, known botanically as Pyracantha coccinea, is a great shrub this time of year due to its evergreen nature and showy berries that last through winter. Despite its fierce thorns, Pyracantha is beautiful and versatile in Tennessee landscapes.

Firethorn grows quickly and, depending on selection, can grow as much as 15 feet tall with a spread of 10 feet. It is not uncommon for this plant to grow more than 2 feet a year. The glossy green leaves are slender, growing from just ½- to 1-inch wide and 1 to 4 inches long. Scarlet Firethorn flowers in the spring with small, white blossoms that have an unpleasant odor.

Pyracantha thrives in full sun to partial shade and well-drained soil. Planting in highly fertile and moist soil will produce rampant growth, which makes the plant more susceptible to fire blight and decreases berry production. Breeding and hybridizing has created disease-resistant selections.

Uses in the landscape will vary by selection. Firethorn can make an excellent hedge or dramatic espalier against a wall. It also performs well as a barrier or cover for slopes in hot, dry areas, and it grows well in containers, too. Other species of Pyracantha exist - like Formosa Firethorn (P. koidzumii) and Roger's Firethorn (P. rogersiana) – but P. coccinea is the most winter hardy and durable for Tennessee.

Firethorn is not recommended for planting around the foundation of a single-story building because it grows too large, too fast. Birds love Pyracantha, but prefer the red-fruiting ones and are likely to strip your plant by Christmas.

It is best to plant Pyracantha in the fall. If berry color is important, buy the plants when they have fruit, as berry colors range from yellow to orange to red. Since Pyracantha resents transplanting, leave it alone once it's planted.

Firethorn can be pruned during almost any season, but winter or early spring pruning is recommended. If you wait until early spring, when flowering occurs, leave some flowers so you will have berries in the fall. Flowers and berries are produced only on growth that is at least one year old.

These are some of my favorite Firethorns and their growth habits:

• 'Apache' – grows to 5 feet high and 6 feet wide with large, bright red berries that last well into winter. Resistant to fire blight and scab.
• 'Fiery Cascade'– grows to 8 feet tall and 9 feet wide and has orange berries that turn red during the winter. Disease resistant.
• 'Gnome' – grows to 6 feet high and 8 feet wide with orange berries. Very susceptible to scab, but also very cold hardy.
• 'Lowboy' – grows to 2 to 3 feet high with a spreading habit. Orange berries. Prone to scab.
• 'Mohave' – grows to 12 feet tall and wide with many big orange-red berries that last well into winter. Resistant to fire blight and scab.
• 'Teton' – grows to 12 feet high and 4 feet wide with golden-yellow berries. Resistant to fire blight and scab. Very cold hardy.
• 'Tiny Tim' – grows to 3 feet high with small leaves and few or no thorns. Red berries.

Sue Hamilton is an associate professor in the University of Tennessee Department of Plant Sciences. She is also director of the UT Gardens, a project of the Tennessee Agricultural Experiment Station. The Gardens are located in Knoxville on Neyland Drive and in Jackson on Airways Blvd. Admission is free, and the Gardens are open to the public seven days a week during daylight hours.

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