The idea of a palm tree swaying in the Midwest seems contradictory. No palm species is native to Missouri, as the state’s natural environment is unsuitable for typical palm survival. However, select varieties of palms known for their exceptional cold tolerance can be successfully grown there. Cultivating these non-native palms requires careful selection and significant protective effort.
Missouri’s Climate and Native Vegetation
Missouri’s climate is classified as humid continental, characterized by four distinct seasons with significant temperature extremes. The state spans several USDA Plant Hardiness Zones, ranging from the colder 5b in the north to the milder 8a in the extreme southeastern “Bootheel” region. Most of the state falls within Zones 6a and 6b, where the average annual minimum temperature can drop to between -10°F and 0°F.
This zone rating indicates that sustained sub-freezing temperatures are a regular winter occurrence, which presents a challenge to most palm species. While the average January temperature hovers around 26°F, the state has recorded extreme lows plummeting to -40°F, which is fatal for almost all palms. The native flora of Missouri consists of temperate deciduous species like oak, maple, and hickory trees, which shed their leaves to survive the cold.
Cold-Hardy Palm Species That Can Be Grown
The possibility of growing palms in Missouri rests entirely on the existence of a few exceptionally cold-hardy species. The two most reliable choices for the state are the Needle Palm (Rhapidophyllum hystrix) and the Windmill Palm (Trachycarpus fortunei). These palms evolved in colder, mountainous, or temperate regions, giving them a survival advantage over their tropical relatives.
Needle Palm
The Needle Palm is arguably the most cold-tolerant palm worldwide, a shrubby, nearly trunkless species. When established, it can survive short periods down to -10°F to -15°F. Its dense, fibrous base protects the growing point, or “heart,” of the palm, which is the most vulnerable part of the plant. It is considered hardy for planting in Zone 5b with appropriate winter care.
Windmill Palm
The Windmill Palm is a popular choice due to its upright, arborescent trunk and fan-shaped leaves. Mature specimens can survive temperatures down to approximately 10°F without severe damage. This species is generally recommended for the warmer Zone 7a and 7b areas of southern Missouri, such as the Cape Girardeau region. Dedicated gardeners attempt it in Zone 6.
Essential Winter Protection Methods
For any palm to thrive long-term in Missouri, active winter protection is mandatory during hard freezes. The primary goal is to insulate the palm’s growing point and root system from extreme cold and wind. Preparing for winter begins with applying a thick layer of mulch, typically three to six inches deep, around the base of the plant. This stabilizes root temperatures and prevents the ground from freezing deeply.
When temperatures are predicted to drop into the single digits or below, the palm’s crown must be wrapped. Materials like burlap, frost cloth, or synthetic blankets should be used to securely cover the fronds and the trunk, especially around the growing point. Supplemental heat can be added inside this protective wrap using outdoor-rated heat cables or incandescent Christmas lights, which provide a low, constant temperature increase.
For smaller palms, a temporary, framed structure, sometimes called a mini-greenhouse, can be built around the plant and covered with plastic sheeting. Ensure the covering does not directly contact the fronds to prevent burn damage. The structure must be removed once the cold snap passes to allow for air circulation. Additionally, deeply watering the palm before a hard freeze can help, as the water acts as a natural insulator within the soil and plant tissues.