Rhubarb is a unique perennial botanically classified as a vegetable, though it is universally treated as a fruit in the kitchen. Its long, thick stalks, which resemble celery, are the only edible part of the plant. The stalks feature a signature intensely tart flavor, which is why rhubarb is often paired with sweeter elements like sugar or berries. This complex, sour profile adds depth to various desserts and savory dishes.
When Rhubarb is Available
Rhubarb availability is split into two distinct harvest periods, offering a long season for consumers. The main, or field-grown, season typically begins in late spring, running from April or May through June and sometimes into July. This outdoor cultivation yields the primary crop, where stalks grow under full sunlight and develop a full, robust, intensely tart flavor. Colder climates often see a slightly later start to this main season.
The earliest availability comes from forced rhubarb, which is ready from mid-winter, starting as early as January and extending through the spring. This type is grown indoors in darkened sheds, restricting light to trick the plant into early growth. The lack of light results in a vibrant pink or crimson stalk and a more delicate flavor profile. Forced rhubarb is generally more tender and less stringy than field-grown varieties, requiring less added sugar.
Selecting the Freshest Stalks
When purchasing rhubarb, choose stalks that are firm and crisp, indicating freshness and good moisture content. The stalks should snap easily when bent; avoid any that appear limp, bruised, or blemished. A slight sheen on the skin is also a good indicator of a recently harvested, quality stalk.
Color is purely an indicator of the specific variety, not ripeness or sweetness. Some varieties are bright red, while others are speckled pink or entirely green. Both red and green stalks can have the same desirable tart flavor and firm texture, so color should not determine your selection. Note that very thick stalks, typically over two inches in diameter, may be tougher and more stringy than thinner, more tender stalks.
Only the stalks of the rhubarb plant are safe for consumption. The large, fan-shaped leaves contain high concentrations of oxalic acid, a compound that is highly toxic to both humans and animals. This acid can cause severe illness, including kidney damage. If you purchase rhubarb with the leaves attached, they must be completely removed and discarded before cooking or processing the stalks.
Storing and Preserving Rhubarb
For short-term use, store unwashed stalks in the refrigerator. Wrap the stalks tightly in foil or place them loosely in a plastic bag within the crisper drawer. This helps retain moisture and maintain crispness, keeping them fresh for up to two weeks. Store rhubarb away from ethylene-producing fruits like apples, which can cause the stalks to deteriorate faster.
For long-term preservation, freezing is the most effective method for capturing the seasonal flavor. Wash the stalks, trim the ends, and chop them into half-inch to one-inch pieces. To prevent clumping, spread the pieces in a single layer on a baking sheet and freeze until solid (flash freezing). Once frozen, transfer the pieces to a heavy-duty freezer bag or airtight container. They can be stored for up to a year and used directly in cooked recipes. Alternative preservation methods include drying the chopped pieces or processing the stalks into jams or chutneys.