The Case of the Giant Lemon

Starting about a year ago, we began noticing behemoth citrus fruit forming on our Meyer lemon tree.  At first it was a funny and curious finding.  Was there a Pomelo grafted to the same trunk?  Is the tree planted over a nuclear waste dump or leaky sewer pipe??

The tree, a dwarf Meyer lemon, was purchased from Home Depot in Napa, CA and transported in its original pot to Vista, CA with us 7 years ago.  We found a permanent home for it in the ground when we removed an 80s-era giant satellite dish in our side yard.  The spot was perfect for our "Charlie Brown tree." Happily in the ground, it gets plenty of sun, has set deep roots, and was able to grow out of its pathetic Charlie Brown state into a full-sized bigger-than-dwarf lemon tree with branches that extend 25 feet up.  The tree has been vigorous and healthy and has produced a bounty of sweet, juicy Meyer lemons for 3 years.  

Two of our giant lemons with a not-yet-ripe normal lemon in front

Two years ago, the mysterious giant fruit started forming.  It took months for these duck-pin bowling ball-sized fruit to ripen (for those of you not familiar with duck-pin bowling - the ball is about 30% smaller than a regular bowling ball).  Finally, one was ripe enough to pick and we excitedly cut it open.  Would it taste like a grapefruit?  Would the fruit be as juicy as the normal lemons the tree produces?  To our disappointment and not all that surprising, the skin and pith were thick and the fruit was pretty unexciting.  It was lemony in flavor but bland and the texture of the fruit was mealy.  Yuck.

But, the mystery prevailed.  We asked our gardener, friends, and neighbors but no one could explain the case of the giant lemons.  Then, a couple of weeks ago, I was touring a newly re-landscaped backyard a few streets away in the neighborhood.  These neighbors had planted several citrus varieties, and I happened to mention the case of the giant lemon.  Without batting an eye, my neighbor questioned - is it larger than a sofball? To which, I answered "yes."  Thick-skinned and pithy?  Again, "yes." And, not very tasty?  "YES!"

My neighbor explained that fruit trees often sprout branches from very low on the trunk.  All common citrus we find in nurseries today are grafted onto their trunks.  When the new branches sprout from the part of the tree below the graft, they produce the exact species of fruit we have - overgrown, pithy, and basically useless.  When I got home I carefully inspected the tree.  In fact, one sizable branch was growing from very low on the trunk.  And, all of the over-grown fruit were hanging on sub-branches from that one branch.  It became clear as day - half the tree that sprouted from that one branch had giant fruit; the other half from branches above the graft line has normal, delicious Meyer lemons.

We have since removed the trunk-size branch growing from below the graft and have shrunk our tree back to its appropriate dwarf size.  We have also learned that it is important, particularly with newly planted citrus trees, to remove early new shoots that grow from the bottom so as not to let them mature to the point of producing fruit.  That way, the shape of the tree is maintained and there will be no overgrown, inedible fruit.

Case closed . . .