Prized for their fragrant fruit, lychee trees (Litchi chinensis) are equally well loved for their evergreen foliage and tidy, rounded growth habit. They are highly frost-sensitive and will only grow outdoors within U.S. Department of Agriculture plant hardiness zones 10 and 11, where they are a common sight in ornamental landscaping. Lychee trees grow reliably well from fresh seeds, although seed propagation poses several challenges that may limit the tree's usefulness in the home landscape.
Only fresh seeds taken from fully ripened lychee fruit will germinate. Look for fruit with a solid red, pebbly skin and strong fragrance. Peel the fruit and eat or discard the juicy, translucent flesh inside. Each lychee fruit contains at least one seed, which is generally round and dark brown in color with a diameter of roughly 3/4 inch. Some lychee fruit contain shriveled or malformed seeds that are colloquially called "chicken tongues." Chicken tongue seeds germinate poorly and should not be used for propagation. Lychee seeds remain viable for only four to five days and should be sown as soon as possible after extraction to increase the likelihood of successful germination.
Sowing and Germination
Lychee seeds germinate reliably when kept under suitably warm, moist conditions. Fill a 6-inch pot with drainage holes with clean, unused potting soil and add water until the soil is evenly moist and the excess water has drained out through the drainage holes. Sow the lychee seed in the center of the soil at a depth of 1 inch. Maintain a temperature of between 75 and 90 degrees Fahrenheit and keep the top inch of soil moderately moist. Most fresh lychee seeds will germinate in one to four weeks, but some can take up to six weeks. Once the glossy, reddish-bronze leaves emerge, move the pot to a sheltered, lightly shaded location.
Aftercare and Transplant
Lychee seedlings grow quickly and will reach a height of 7 to 8 inches in a matter of weeks. However, their growth slows significantly after the initial spurt and they will stay below 1 foot for up to two years while producing a dense, productive root system Keep young lychee trees sheltered from drying winds and direct sunlight, and provide 1 inch of supplemental water each week to keep them hydrated. Slowly acclimate them to full sun in autumn of their first year. In spring or autumn of their second year, transplant them 15 to 20 feet apart in a sunny bed with acidic, fast-draining soil.
Gardeners hoping to grow a fruit-bearing lychee tree from seed are likely to be disappointed. Lychee seeds are highly variable and the resulting tree can take anywhere from five to 25 years to bear fruit, if it fruits at all. Additionally, the quality and quantity of fruit are unlikely to match that of the parent tree. Seed-grown lychee trees are best used as ornamental shade trees because their glossy, evergreen foliage and rounded growth habit will remain even if their fruit-bearing capabilities are lacking.