How to Grow and Care for Rough Lemon

The rough lemon, Citrus jambhiri, is a distinct citrus variety recognized for its hardiness and unique appearance. Believed to be a hybrid of a citron and a mandarin orange, this fruit is cultivated for its aromatic lemons and is also widely used as a rootstock in commercial agriculture. Originating in Southeast Asia, its adaptability has led to its cultivation worldwide.

Identifying a Rough Lemon

The rough lemon is identified by its peel, which is lumpy, uneven, and covered in deep creases, giving it a gnarled look. When ripe, its color ranges from a pale yellow to a deeper golden yellow-orange. The fruit often features a prominent nipple at one end, making it visually distinct from common lemons.

The fruit is medium to large, averaging seven to eight centimeters in diameter, and can be round or somewhat flattened. Internally, it has a thick, spongy white pith beneath the rind. The pale-yellow flesh is divided into about ten or eleven segments and contains many cream-colored seeds.

The rough lemon’s flavor profile differs from common varieties like the Eureka or Lisbon. While still acidic, it is often described as slightly sweeter and less tart. Its aroma is also notable, with bright, floral, and fruity notes. The juice combines these tangy and sweet elements for a complex taste.

Common Uses of the Fruit

Rough lemon juice is versatile and can be used like standard lemon juice in salad dressings, marinades, and sauces. It also works well in beverages like lemonade, iced tea, or cocktails. Its slightly sweeter profile makes it an interesting component in both savory and sweet dishes.

Its thick rind makes the rough lemon well-suited for marmalades, jellies, and other preserves. The peel can also be candied for use in baked goods and confectionery. While the zest is aromatic, its bumpy surface can make zesting more challenging than with smooth-skinned lemons.

The aromatic oils in the rough lemon’s rind make it useful as a natural cleaner or deodorizer. Historically, its thick rind helped it last on long sea voyages, providing sailors with a source of vitamin C. The tree’s leaves can also be used to make tea or to flavor cooked dishes.

Growing Rough Lemon Trees

Rough lemon trees thrive in warm climates, specifically USDA hardiness zones 8 through 11. They require a location with full sun, receiving at least six to eight hours of direct sunlight daily. For best results, plant in the spring after the danger of frost has passed.

The tree requires well-draining soil to prevent root rot, with a sandy loam at a slightly acidic pH of 5.5 to 6.5 being ideal. Water consistently while the tree is young and establishing. Mature trees are drought-tolerant but still need water during prolonged dry spells.

Feed the tree regularly with a fertilizer formulated for citrus. Pruning is done to maintain the tree’s shape, improve air circulation, and remove dead or crossing branches. When planting, make the hole wider than the root ball to allow roots to expand.

The Role of Rough Lemon as a Rootstock

In commercial horticulture, the rough lemon is often used as a rootstock. This involves grafting, a process where the top of a desired citrus variety (the scion) is attached to the rough lemon’s root system. The resulting tree combines the hardy roots of the rough lemon with the fruit characteristics of the scion.

Using rough lemon as a rootstock has several advantages. It is known for vigorous growth, which helps establish large, productive trees quickly. This rootstock has high drought tolerance and performs well in poor, sandy soils, often resulting in high fruit yields for the grafted scion.

This rootstock choice also has disadvantages:

• It is highly susceptible to citrus blight, a serious disease that can cause tree decline.
• It is vulnerable to Phytophthora root rot, especially in poorly drained soils.
• It is susceptible to infestations from citrus nematodes.
• It can negatively impact the quality of the scion’s fruit, leading to a thicker rind, lower juice content, and reduced acidity.