Answer: You may not get fruit from your lychee tree every year because fruit production is closely related to winter and summer temperatures. The problem is that the lychee tree originated in southern China which has wet, humid summers and dry cool winters.
The other problem we have is the lack of "early heat". In China and in Florida, where these trees set fruit reliably, the heat arrives in March. This way the fruit has plenty of time to ripen and by August the lucky people who live in these area are enjoying their lychee fruit.
While you cannot control the weather, you can hope for a cool winter and an early summer so your lychee will produce fruit.
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