Soil and Site Basics
The "Short and Sweet" from Grandpa:
• Soil and Site aren't the same.
• Find out your hardiness zone.
• Do you have a "micro-climate" to grow in?
• Try to plant your fruit at higher relative elevation.
• Plant in full sunlight. Fruit can't be "made in the shade".
• Try to plant in well drained soils, with proper pH and good organic matter content.
• Watch out for deer and other critters! They are just waiting for you to plant.
Grandpa's "long winded" answer: Grandpa used to tell a story about a blueberry grower friend, who was always buying another farm, planting it up with something, and getting bigger and bigger. Grandpa asked him if he was ever going to stop and Cal said, "Probly not, if ya got dirt, ya gotta plant something in it!"
There's a big difference between soil and site! Soil is what you plant in. Site is where the soil is. It may be a toss up about which is the most important, but they definitely are intertwined, and you need both a good enough soil and a good enough site to grow "good enough" fruit. Site considerations: General hardiness zone, climate, relative elevation and light level are the main site characteristics to be concerned about.
Hardiness Zone: You can usually grow a fruit tree outside of its appropriate hardiness zone, but since the goal is to pick fruit, you need to make sure that the variety you have selected will be productive in your hardiness zone. Go to the USDA hardiness zone map and determine your particular hardiness zone. The United States Department of Agriculture (USDA) has studied and determined hardiness zones all across the country. In general, most of the fruit trees in Grandpa's Orchard™ are very suitable for hardiness zones ranging from 5 to 7. In Zone 8, many of these fruits will grow well also, but because the winters are very mild there may be difficulties with some varieties not breaking dormancy because of too few cold days in the winter. In "sub-tropical" Zones 9 and 10, most of the varieties in Grandpa's Orchard™ will not do well. In Zone 4 and particularly 3, you should probably stick with only the hardiest varieties.
However, if you are somewhat of a gambler and want to feel like a real farmer and take some risk, you can try growing varieties outside of their hardiness zones. Often you will be successful, but the real gamble is when one of those record cold years [frequency and severity of which is how they determine the Zones] comes along and freezes off your fruit buds (if you are lucky) or cold damages the trunks and limbs or just plain kills your trees (if you are unlucky). Place your bets!
Climate is a related to hardiness zone, but more involved. While hardiness zones are determined basically by how many "killing" freeze events occur over a long period of time, climate is more like the average that you live through every spring, summer, fall and winter. Most commercial fruit production is concentrated in "moderate" climates that have fewer extremes of heat and cold. Often, these are "micro-climates" that are smaller areas in the larger geography that have more moderate and nicer growing conditions than the rest of the area. The western shore of the lower peninsula of Michigan (the "Fruit Belt") is a perfect example. Because of the size and breadth of Lake Michigan, the "fruit belt" grows as diverse a range of fruit crops as anywhere in the U.S., except for California.
One of Grandpa's old friends, and a great peach breeder, once called his little corner of southwest Michigan the "banana belt", only partly in jest, because it can often times be such a moderate climate. No, bananas really don't grow there! If general, look around, if others are raising fruit then you can too. If you don't see any, do a little research. If others are raising tender ornamentals, outside their normal hardiness zones, then you have a decent chance of being successful with fruits with the approximate same hardiness rating. Gamble a little anyway!
Relative Elevation: In general, fruit trees will produce better on sites that have more vertical elevation and air drainage, than on flat sites where cold air tends to settle and blanket the ground on colder nights. Fruit trees are susceptible to both winter cold temperatures (hardiness zone) and spring cold temperatures when in bloom (frost sensitivity). There is no real insurance policy to protect you from spring frost. The best insurance is a good site and proper variety selection. If possible, chose a site with higher relative elevation, at the top or side of the hill (if you have one) rather than at the bottom. On frosty nights, cold air will settle and "flow" down the slope and "pool" at the lowest spots.
If you have a big enough cold air reservoir, then you have a better chance of surviving normal spring frosts. On frosty mornings, you can often see a frost line, above which fruit trees will be better off. But, don't despair if you have a flat site. Often, by planting a more vigorous rootstock, and training the tree to grow higher, then you can often set good crops above the frost lines on flat ground. Finally, if spring frost is a habitual problem, try to choose varieties that are known for their frost tolerance and later blooming characteristics.
Sunlight! Almost all fruit trees require full sun all day long for best production. Don't plant in shady locations that don't get at least half a day of full, direct sun light or you can expect weak, spindly trees, poor foliage, and pathetic fruit set! Fruit trees are sun lovers!
Soil considerations: You can almost always find a way to grow a productive fruit tree in almost any kind of soil, except a swamp, and then I bet Grandpa could have figured something out. There often are choices of rootstock to match soil types. There are management and planting systems to help with challenging soils. Soil drainage is probably the most important factor. Poorly drained and water logged soils are the most challenging.
If you dig a hole a foot or so deep in the ground during the "dry" period of the year, and it fills up with water, you probably will not be too successful in keeping fruit trees growing without some real help. If you live in an arid climate, where it is always dry, you can still have soil drainage problems, because you will have to irrigate to make your fruit grow. If you dig a hole, fill it with water, and it doesn't drain out within a day, then you have tight, poorly drained soil that you will have to deal with.
Soils that drain well always have good potential to grow fruit. On really poorly drained soils, you may have to mound where you plant a tree, or tile and ditch to carry off excess water.
pH gets a lot of attention from the garden experts! Grandpa doesn't exactly say "pHoohy" to the subject. It is well known that fruit trees will grow in a wide range of acidic to alkaline soils. It IS best if you can get your soil to read in the 6.5 – 7.0 pH range, but even if it is well below 6.0, even down to 5.0 or higher, or much more alkaline, up to 8.0, there are ways to adjust pH up (liming) or down (acidifying) to get a more desirable pH range. Grandpa would recommend that you test the pH of your soil so that you know where you are starting from.
If the pH is lower than 6.0 than you probably should do some liming to raise it closer to 7.0. If it is very alkaline, over 7.5, acidifying to lower the pH might be recommended. Over time, most soils in areas with generous rainfall tend to drop in pH because of "acid rain" and also because of normal fertilizing practices, which tend to acidify soil over time. It is much easier to adjust pH before planting, rather than after planting.
Humus and organic matter: You can grow a fruit tree in pure, dune sand if you work at it, and a lot of good fruit sites in many fruit growing areas are very sandy, but all sandy soils benefit by having more organic matter and humus in them. Adding peat, compost, or manure to very sandy soils will bring up the organic content and make growing easier, by allowing for better moisture and fertilizer retention and general soil life. Adding too much fertilizer rich compost or manure can cause even sandy soils to become more vigorous than one might want for fruit production, though, so use common sense. "Green" manures grown as cover crops, such as rye, oats, Sudan grass, and other green, low crops that you can turn under and let rot into the soil are another way to increase organic matter over time.
Critters! Native, wild deer have often become limiting factors in some commercial orchard sites, more so than climate, site and soil factors. Other wild critters can take a liking to fruit trees and be destructive also. If you see deer and rabbits on a regular basis during the daytime, then you IMMDEIATELY need to be prepared to take action to protect your fruit trees from damage right from the get go!. Both can literally put you out of business overnight. Even if you don't see them, prepare to take action at the first hint of damage.