What type of soil should I use with fruit trees?

Question

Background: We live on a large mountain. And the soil we have here is full of small, medium and large rocks everywhere. Throughout the time we've lived here, growing trees is really hit and miss. Due to our ignorance of planting trees and types of soil to use.

I know now that specific trees require specific elements (nitrogen) and a specific pH level in the soil in order to thrive.

1. Should I remove S/M/L rocks from the existing soil before planting new fruit trees?
2. Should you ever use top soil when planting new trees when replacing existing soil?
3. If not (2), then what type of soil is recommended for planting fruit trees?
4. How often should someone water fruit trees?
5. Is there a general understanding of the elements needed for planting fruit trees, and the pH level in the soil?

Answer 1

There are usually two solution of the problem: one is your solution: change the soil, the second (which I usually prefer) is to change the species.

Your question is very generic (on the other hand, I like to see generic answers, because it helps to see how other "gardeners" think and work.

Mountains are difficult places, because soil/rock origin varies a lot: a range of mountain usually share a common rock type, but locally (and within few feet) the rock could have different origin. Also soil depth varies a lot.

Many fruit tree doesn't care about rocks, and in any case you cannot remove rocks in such deep. Just a rocky soil has less nutrient and less water, so you should water more often and distribute fertilizer more often (still same amounts). Cherry trees have shallow roots, so they doesn't care so much. Grape vine and apples are often cultivated in rocky soils.

Changing pH and soil is often a problem, especially for trees: it is difficult and it take a lot of maintenance: pH will tend to reset (because of water flowing in and out, so it will tend again to the original pH), and also nutrients will flow away. I would have a not-rocky good soil near the trees, which helps reducing watering and fertilizing takes, but I would try not to change the pH of the soil (but maybe for few plants): too much work on long term, for a never sure outcome).

Your question 4 and 5 are too generic. Every species and varieties/cultivars have different needs. Trees could eventually find water below the surface, so you should also observe your trees to find when and how much to water. Observing wild trees also helps: get a local flora, and try to identify the trees, and which one likes dry or wet soil, which one want a acid soil and which one a higher pH. With such easy observation, you get much more information about your soil type (and maybe you will see that you have different soil types), than chemical soil analysis (which are biased on shallow depth and previous works/fertilizers on the collecting points).

[A pro tip: check our our neighbor gardens: it help you to find which trees growth well with your climate and soil]

Answer 2

When in doubt, plant what's growing wild - or plant a well-researched cultivar of the wild plants. You'll want to make sure that any cultivar has the same cultural requirements - especially water - that the species does.

Here's a site to get you started http://www.laspilitas.com/groups/native-trees.htm

I never replace soil when planting a shrub or tree (and almost never when planting perennials). If the soil is "native" to the site (hasn't been stripped and sold when a house was built), then that is what a native plant will grow in. Digging a hole and replacing "lousy" soil with "good black dirt" really just creates a large flower pot - the tree's roots won't easily leave the tasty soil you provided for them, stunting growth and often leading to an early death.