The mandarin tree, a compact and evergreen member of the citrus family, is a popular choice for home growers due to its manageable size and sweet, easy-to-peel fruit. These trees feature aromatic, glossy green leaves and produce white flowers that precede the fruit. Growing mandarins offers a rewarding experience, whether cultivated in the garden or in a container on a sunny patio. The success of a healthy, fruit-bearing tree depends on providing specific environmental conditions and consistent care.
Site Selection and Preparation
Selecting the proper location is the first step toward establishing a mandarin tree, requiring a spot that receives full sun exposure for at least six to eight hours daily. The tree needs this light for healthy growth and abundant fruit production. While mandarins are among the more cold-tolerant citrus, thriving best in USDA hardiness zones 8 through 11, they must be protected from hard freezes.
The soil must offer excellent drainage, as waterlogged conditions can quickly lead to root problems. Mandarin trees prefer a slightly acidic to neutral soil pH, ideally ranging between 5.5 and 6.2. If the native soil is heavy clay or drains poorly, planting in a raised garden bed or a large container is a necessary alternative to ensure the roots do not sit in standing water. For those in cooler climates, a container allows the tree to be moved indoors when temperatures drop close to 20°F.
Planting and Initial Establishment
When planting a nursery-grown mandarin tree, dig a hole that is approximately twice the width of the root ball but no deeper than the root ball’s height. This wide, shallow hole encourages the roots to spread outward into the surrounding soil. It is important to ensure the graft union, the slightly swollen area where the fruiting variety meets the rootstock, remains several inches above the final soil line.
Burying the graft union can lead to crown rot or allow the rootstock to sprout unproductive suckers. After positioning the tree, gently backfill the hole with the original soil and firm it lightly to remove any air pockets. A thorough, deep watering immediately after planting is necessary to settle the soil around the roots and minimize transplant shock. Do not apply any granular fertilizer at this stage, as the initial focus should be on root establishment.
Ongoing Nutritional and Structural Maintenance
Consistent, deep watering is a fundamental component of mandarin tree care, particularly during the active growth phases of spring and summer, as well as during flowering and fruiting. Instead of frequent, shallow sprinkles, water deeply enough to saturate the entire root zone, then allow the top few inches of soil to dry out slightly before watering again. Container-grown trees require more frequent checks because their soil dries out faster than ground-planted trees.
Mandarin trees are heavy feeders and require a fertilizer formulated specifically for citrus, which is high in nitrogen. A common schedule involves splitting the annual application into three parts, applied in late winter or early spring just before bloom, again in early May, and a final application in June. Fertilizing later in the season should be avoided, as it can delay fruit coloring and affect the quality of the developing fruit.
Pruning helps maintain the tree’s health by promoting air circulation and light penetration within the canopy. The primary goal is to remove any dead, diseased, or crossing branches. It is important to consistently remove any suckers that emerge from below the graft union, as these originate from the rootstock and will not produce desirable fruit. When shaping the tree, avoid excessive internal thinning that exposes the inner branches to direct sunlight, which can cause sunburn on the bark.
Protecting and Harvesting the Fruit
Mandarin trees are susceptible to common citrus pests such as aphids, scale insects, and citrus leafminers. Maintaining a healthy, well-fed tree is the first line of defense against infestations. For active outbreaks, organic management strategies like applying horticultural oil or insecticidal soap are effective.
Mandarins will not increase in sweetness after they are picked, so timing the harvest is crucial to ensure the best flavor. The fruit is typically ready when it achieves its full, characteristic orange color and feels heavy for its size, indicating a high juice content. Since the skin can color before the sugar content peaks, the most reliable test is to pick one fruit and taste it for sweetness. Mandarins should be harvested by cutting the short fruit stem with clean snips, rather than pulling, which prevents damage to the tree and helps the harvested fruit store longer.