Best Practices for Growing Lychee Trees

There are two "rules of thumb" I have learned to follow after two decades of growing lychee trees.

• Provide good wind protection.
• Provide a growing environment consisting of organic mulch and organic compost.

These basic principles apply universally, whether you are a dooryard grower or a grove owner.

In the following discussion I will elaborate on both concepts.

Lychee trees grow in recurrent flushes of growth followed by periods of dormancy. Depending on the ambient temperature and availability of nutrients the dormancy phase of the growth/dormancy cycle can be shortened down to almost nothing, thereby resulting in an almost continuous growth phase.

The new growth on a lychee tree consists of very delicate leaves which emerge (if the tree is healthy) as a wine red flush, becoming darker green as the growth hardens off.

Figure 1:  Delicate new lychee growth flush

This delicate new growth is easily damaged by wind and the damage becomes progressively worse as the wind speed exceeds 15 mph.

Figure 2: Wind damaged leaf

Lychee trees must re-grow new leaves periodically as the photosynthetic capacity of the leaf diminishes with age. If all or some of the new growth becomes damaged the production of photosynthetic exudates will decrease, which will slow the expansion of the root system. An abbreviated root system will not support much of a canopy. This is why trees grown in a container can only attain a limited size.

Figure 3: Protected Side of Grove

Figure 4: Exposed Side of Grove

Grove planted trees, more directly exposed to the prevailing winds, almost always grow more slowly than the interior trees. In Florida the prevailing winds are from the East (NE, East, SE) with an occasional west wind accompanying an approaching cold front.

Figure 5: Artificial Shadecloth Windbreak Installed at One End of a New Grove

There are several informative articles on this website www.lycheesonline.com which deal with the advantages of using organic methods in the culture of lychee trees. The most important article is the http://www.lycheesonline.com/soilbiologyprimer.cfm by Elaine R. Ingham .

This landmark article is effectively the "Bible" of organic farming (gardening) and should be read by anyone considering organic techniques.

Figure 6: The Soil Food Web

As I have often described, lychee trees originated in mountain rain forests in Southern China, Thailand and North Vietnam. The soil ecosystem of the sub-tropical mountain rain forest is extremely complex making the relationship between soil organisms that convert nitrogenous organic material into a form of nutrition which can be utilized by the tree is equally complex.

It is not surprising that when the soil environment surrounding the rhizosphere (root zone) of a lychee tree approximates that encountered in the primal mountain rain forest environment the trees thrive and grow rapidly.

There are two basic components comprising a healthy organic soil environment. Mulch and compost are the two essential elements that comprise a healthy organic soil environment.

We define mulch as the slightly decomposed material that results from shipping/shredding tree leaves branches and trunks. Most landscape and tree maintenance companies use industrial machines to process tree parts.

Figure 7: A Vermeer Industrail Chipper

Figure 8: Grove Mulching on a Large Scale

Figure 9: Bulk Mulch Spreading

A "good" mulch strikes an even balance between woody material that decays slowly and rapid deteriorating leafy material which is a primary nutrition source for detritivores. Earthworms are an example of a detritivore, which are major decomposers of dead and decomposing organic matter. They derive their nutrition from the bacteria and fungi that grow upon these materials. They fragment organic matter and make major contributions to recycling the nutrients it contains. Earthworms stimulate microbial activity, mix and aggregate soil, increase filtration, bury and shred plant residue and provide channels for root growth.

Mycorrhizal fungi, an important soil organism (mushrooms are the reproductive fruiting body of mycorrhizae) , thrive on the slowly decaying woody residue. The presence of soil Mycorrhizal fungi can greatly enhance the absorptive capacity of the root system. To learn more about soil microbes and their importance, read the informative article by professor Emeritus Al Will http://lycheesonline.com/MicrobialRevolution.cfm

We characterize organic compost as deteriorated vegetative matter. As depicted in the photo below the discarded material from your kitchen or garden. that otherwise would be consigned to the garbage disposal. This material is actually a very valuable resource of "fast" nitrogen, which can be used to "feed" the soil food web and indirectly the root system of your lychee tree.

Figure 10: Typical Organic Kitchen Waste

Figure 11: Organic Kitchen Waste Shredded

Many types of organic composters are commercially available. Composters which can conveniently be rotated and have internal aeration, which enhance aerobic bacterial decomposition, are especially effective. A plastic bucket with a cover will also do the job.

Figure 12: Compost Tumbler Cross Section

Figure 13: Compost Tumbler

The mulch applied around a lychee tree should be spread out past the drip line to a distance of 3-4 feet for a 3 gallon sized plant.

Figure 14: Properly Mulched Tree

This mulch provides an organic environment which retains moisture and maintains soil temperature. To demonstrate the effectiveness of this mulch go ahead and move some aside. Underneath, you will notice earthworms, various arthropods (springtails, orbatid mites, centipedes, millipedes etc.) and the presence of numerous microscopic organisms (not visible) such as protozoa, nematodes, fungi and bacteria.

The root system of the lychee will extend out under this layer of mulch and as the roots expand, the canopy will increase proportionally in size.
In the photo below you will observe a tree in a 3 gallon size container and a tree in the ground. Both of these trees were from the same batch of air layers and are the same age. The difference is that the tree in the ground has been there 8 months and it has been wind protected, mulched and fed with organic compost.

Figure 15: Three Gallon Tree (Sweetheart) next to Protected/Mulched Tree

Figure 16: Same Tree 4 months prior

The following photos illustrate the stark contrast between two trees of the same age. One has been grown in a protected area and the other was grown in an exposed grove without mulch or organic fertilizer.

Figure 17: Wind Protected Lychee (Sweetheart) Grown with Organic Compost

Figure 18: Unprotected Lychee (Sweetheart) No Mulch/No Compost after 1 year

This article was last updated on: April 30, 2010