Rhubarb (Rheum rhabarbarum) is a cool-season perennial vegetable whose tart stalks are widely used in desserts. Its popularity in northern climates leads many gardeners in warmer regions to attempt its cultivation. The challenge of growing this plant outside of its preferred chilly environment is significant. This article explores the specific biological needs of rhubarb and determines if and how it can be successfully grown across the diverse climate zones of Texas.
Rhubarb’s Essential Climate Requirements
The perennial nature of rhubarb depends entirely on its need for a prolonged period of cold dormancy, a process known as vernalization. To reliably break dormancy and produce thick, harvestable stalks, the root crowns require exposure to temperatures at or below 40°F (4.5°C) for several weeks, typically six to ten weeks. Without this chilling period, the plant’s production declines, eventually leading to failure.
Rhubarb thrives in average temperatures between 32°F and 77°F (0°C and 25°C). Prolonged summer heat, especially when temperatures consistently exceed 75°F (24°C), causes severe stress. When overheated, the stalks become thin and spindly, and the plant may prematurely “bolt,” or send up a seed stalk, which signals the end of its productive season. The plant may also enter a period of summer dormancy or succumb to the stress.
The plant’s shallow, fleshy root system is particularly vulnerable to elevated soil temperatures, which is a major factor in its decline in hot regions. In its native cool environment, the soil stays consistently chilled. When the soil warms considerably, the roots struggle to provide the necessary moisture and nutrients, compounding the heat stress on the above-ground stalks.
The Feasibility of Growing Rhubarb in Texas
The vast climate range of Texas makes growing rhubarb a regional question with two very different answers. In the state’s northernmost reaches, such as the Panhandle, where USDA Hardiness Zones are cooler (Zone 6), perennial growth is possible. These areas often receive the necessary chill hours for the plant’s vernalization requirement to be met annually.
However, for Central, South, and Coastal Texas (Zones 8-9), perennial cultivation is extremely difficult or generally impossible due to insufficient winter chill and scorching summer heat. The combination of high temperatures and humidity in these regions is often fatal, leading to both heat stress and increased susceptibility to fungal rot. Traditional rhubarb culture, where the plant is established for multi-year harvests, is not successful here.
For the majority of the state, the plant must be treated as a cool-season annual. Gardeners in warmer zones must accept that the plant will not survive the intense summer months. The strategy shifts to maximizing growth during the mild winter and spring before the onset of summer heat. This annual approach ensures a harvest without attempting to force the plant into a multi-year cycle it cannot sustain.
Strategies for Successful Warm-Climate Cultivation
To succeed in the challenging Texas climate, gardeners should adopt the technique of treating rhubarb as a winter annual. This involves planting crowns or seeds in the late summer or early fall, typically August or September. This allows the plant to establish its root system during the cool season. The rhubarb will grow slowly through the mild winter, accelerating rapidly in the late winter and early spring months.
The harvest should be completed by late spring, usually by May or early June, before the most intense summer heat arrives. After this single harvest period, the plants are generally discarded. This method bypasses the perennial challenge entirely, focusing only on the plant’s productive cool phase.
Specific cultural practices can help mitigate the effects of the heat the plant does experience. Planting in a location that receives afternoon shade is beneficial, as it protects the plant from the most intense solar radiation. Heavy mulching with an organic material, such as straw or wood chips, is an effective technique to insulate the soil and keep the shallow root zone cool.
Selecting varieties specifically noted for heat tolerance can also increase the chance of success. Cultivars like ‘Victoria’ (often grown from seed), ‘Chipman’s Canada Red’, ‘Hardy Tarty’ (also known as ‘Colorado Red’), and the Australian-bred ‘KangaRhu’ are known to perform better in milder climates. These varieties are less prone to bolting and can sustain growth deeper into the spring than traditional northern varieties, maximizing the short harvest window.