About
Rambutan, also known as hairy lychee, is a tropical broadleaf evergreen tree known for its juicy, flavorful fruit. Native to Southeast Asia, rambutan requires moist, well-drained soil, year-round fertilizer, and very warm, sunny conditions.
Like longan and lychee trees, rambutans are members of the soapberry family. The fruits have a hairy-looking outer shell containing sweet, floral-tasting flesh that surrounds a large, inedible seed. Here's everything you need to know to grow rambutan plant.
How to Plant Rambutan
When to Plant
Plant rambutan seedlings outdoors in spring once night temperatures are consistently above 60 degrees.
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Selecting a Planting Site
Choose a site with full sun conditions and loamy, well-drained soil. If possible, select a site that is protected from harsh, drying winds.
Spacing, Depth, and Support
Ensure that there's a clear space of at least 15 feet around the planting site for the tree to spread as it matures. Dig a hole that's at least twice as wide and the same depth as your rambutan plant's root ball. Remove the plant from its pot and place it in the hole.
Fill in the hole so that the soil level hits the same spot as it did in the container. Additional support usually isn't necessary.
Rambutan Plant Care
Light
Plant rambutan in a spot that gets full sun—at least six to eight hours of direct sunlight per day. A site with partial sun for at least 12 hours per day could also work.
Be sure to gradually acclimate seedlings or saplings that have been cultivated indoors over a few weeks before planting them outdoors in full or partial sun.
Soil
Rambutan plants prefer rich, loamy, well-drained soil with a slightly acidic pH (5.5 to 6.5). Avoid planting in areas with heavy clay soils that will retain excess moisture. If you're growing a rambutan plant in a container, use a high-quality potting mix amended with perlite or coarse sand for drainage.
Water
Water rambutan plants regularly so that the soil remains consistently moist but not soggy. Unlike some other fruit trees, rambutans are shallow-rooted and can experience leaf drop after only a few days without water.
However, two to four weeks of water stress can help induce flowering. Add a few inches of organic mulch such as wood chips around the base of the tree to the drip line to help retain soil moisture. Leave 3 to 5 inches of space between the mulch and the stem or trunk of the tree.
Avoid letting rambutan plants in containers dry out. Check soil moisture and water when the soil begins to feel dry to the touch.
Temperature and Humidity
Rambutan plants thrive in temperatures between 70°F and 95°F during the day, though they can withstand temperatures around ten degrees cooler and hotter than that range.
Temperatures below 50°F can damage young growth, and conditions below 40°F can cause leaf drop. High humidity of around 75 percent is ideal.
Fertilizer
Rambutans are heavy feeders, meaning they require regular fertilizing throughout the year to bloom and bear fruit. Feed plants with a balanced liquid plant fertilizer year-round.
Rambutan's fertilizer needs will vary as the plant blooms and produces fruit. In winter, change to a 15-30-15 fertilizer to promote blooming, then a 20-10-30 fertilizer to help with fruit set after the plant flowers. After harvesting, return to balanced fertilizer.
Pollination
Rambutans are naturally dioecious, meaning that a female tree they must be pollinated by a male tree to bear fruit. However, many cultivars are self-pollinating and don't require a second tree to fruit.
Types of Rambutan
The two main types of rambutan are red and yellow, which is typically how rambutan plants are categorized in the U.S. However, dozens of different cultivars are available in the plant's native range of Southeast Asia, including:
Nephelium lappaceum 'Binjai': This high-yielding red rambutan cultivar with firm fruit is the most widely grown in Indonesia.
Nephelium lappaceum 'Rongrien': This oval-shaped variety is native to Thailand and turns red with green tips on its hairs at maturity.
Nephelium lappaceum 'E35': This compact yellow rambutan cultivar has very sweet fruits that are particularly juicy.
Nephelium lappaceum 'School Boy': Deep red shells with green hairs conceal small, sweet fruits that grow profusely on this rambutan cultivar.
Harvesting Rambutan
Rambutan plants grown from seed can bear fruit in five or six years, though grafted or budded trees can fruit in as little as two years. In tropical climates, trees may bear fruit twice—once in late fall or early winter and again in late spring or early summer.
Expect fruits to ripen between 12 and 16 weeks after flowers bloom. When they're ready to harvest, fruits will be completely red or yellow and at peak sweetness. Fruits won't ripen off the tree, so it's best to wait until they are fully ripe to pick.
Mature trees can bear several thousand fruits in each harvest.
Pruning
There's no need to prune rambutan plants regularly, but it's a good idea to remove dead or damaged branches as you see them. Pruning after fruiting can help encourage new growth and keep the tree a manageable size.
Propagating Rambutan
Rambutan plants can be propagated by sophisticated techniques like grafting and budding, but air layering is easier and simpler for the home gardener. Rambutan plants respond well to air layering, which involves rooting a branch or section of stem while it's still on the mother plant.
The best time to propagate rambutan is in spring or summer. Before you begin, you'll need a healthy mother plant, a sterilized blade, sphagnum moss, clear plastic, aluminum foil, and string or twist ties. Here's how to propagate rambutan.
Soak a few handfuls of sphagnum moss in water until it's well saturated. Remove the moss and squeeze it to remove excess moisture.
Identify a vertical branch on the mother plant that gets plenty of sun. Use a sharp blade to remove a 1 to 2-inch area of bark all the way around the branch.
Wrap the damp moss around the exposed area of branch, then wrap a piece of clear plastic around the moss so that no moss is exposed to the air. Use string or twist ties to fasten the plastic around the moss and branch. Wrap the foil around the plastic to shield the moss from direct sunlight.
After about 12 weeks, the branch will have grown roots into the damp sphagnum moss. Cut the branch below the root ball and plant it in a container.
How to Grow Rambutan From Seed
It's possible to grow rambutan plants from seed—including seeds you've saved yourself from a ripe rambutan fruit. The fresher the seeds are, the better your chance of germination.
Carefully remove the flesh from around the seed, avoiding cutting or bruising the seed in the process.
Rinse the seed to remove any residue from the flesh, then soak it in room-temperature water overnight.
Plant the seed in a small container of fresh potting mix one inch deep with the flat part of the seed pointing down.
Water the soil and keep it consistently moist.
Keep the pot in a bright, very warm place, or use a heat mat to warm the soil. The rambutan seed should germinate within two weeks of planting.
After the seed sprouts, put it outdoors in a place that gets full, direct sunlight. If keeping the seedling indoors, use grow lights to provide adequate light.
Overwintering
If you're keeping a rambutan plant in a container outdoors, you'll want to begin the process of bringing it inside a few weeks before night temperatures drop below 60 °F.
Gradually acclimate the plant to shadier conditions over two weeks or so. When you're ready to bring it in for good, follow steps for bringing plants indoors for the winter, such as soaking the root ball to drive out insects and inspecting foliage for pests or damaged leaves.
Common Pests and Plant Diseases
Common pests such as fruit flies, moths, fruit borers, and fruit webbers can affect rambutan plants. In tropical regions, birds may also eat green or ripe fruits.
While rambutan plants aren't susceptible to many plant diseases, they may be affected by fungal issues like powdery mildew.