Q.
Which fruit trees are best planted in rocky soil?
A. As long as trees get the right amount of water and the right kind of fertilizers you can grow fruit trees in marbles!!! The more soil is present, the less often fruit trees are watered and fertilized. The more rocks means fertilizer needs to be applied more often. Granular, quick release fertilizers (many inexpensive fertilizers) should be applied about every 8 to 10 weeks. Slow release fertilizers are applied about every three months.
Fruit trees that are tender to winter cold (they will freeze) should be finished with their fertilizer applications in time for cold weather. So if cold weather usually comes no later than mid December (the Las Vegas area is an example of this) then fertilizer applications should be finished by about August 1.
Rocky soil, to me, means soils low in organic content as well as full of rocks.
In the desert, these soils may be growing fruit trees that are productive but
can handle soils covered in rock on the surface of the soil better than some
other fruit trees. I am guessing this definition could be extended into a
prepared soil covered with a two to three inch layer of rock.
Stone fruit trees are like apricots,
plums, and peaches; those trees that produce fruit that have a hard “pit” in
the center. Stone fruit trees are among the best trees, in general, to grow in
rocky soil because of their root’s tolerances to low soil organics, root
structure and ability to suck up water from the soil at low levels of soil moisture.
Fig trees can get large, over 40 feet
tall, but they also can handle severe pruning to keep them smaller. We have
done that over and over at the University orchard in North Las Vegas and have
had no issues with it for 15 years! Remember to give them extra water, above
and beyond what they need for their growth, if you want them to hang on to
their fruit and be productive. Unlike their water needs for growth, they need
more water to produce fruit during the hot summers.
Olive trees a make it onto my list of
recommended fruit trees to grow in rocky and low organic soils even though it
is not used that much by some. Olives can be grown (outside Clark County) for
fruit production. The fruit is either used as a condiment (green or black
fruit) or the fruit is extracted for its oil (olive oil) or both.
Citrus is probably the most often asked
about fruit tree regarding soil organics. Yes, there are huge differences among
citrus and their organic requirements. Most citrus are tropical to semitropical
which include the true lemons, oranges, clementines and grapefruit. All four of
these types of citrus do okay in rocky soils or grown under rocky surface
mulch.