When size is no object, any type of fruit tree will do, but even if you have a small yard, you don't have to give up on the idea of fresh fruit--you can still have fruit trees in your garden. Plan your space and know your limitations, and investigate all of the varieties of small fruit tree species and other planting methods that can help you be successful with fruit trees in a small yard.
Plant low to the ground berries like strawberries and surround the area with small berry bushes for a variety, including blueberry, blackberry, raspberry and mulberry. The bushes take a year or two to take hold and produce fruit, but once they establish themselves, they are there to stay. Strawberries last a year or two and require re-planting, but produce immediately and provide a bountiful crop in small areas.
Several popular fruits come in dwarf varieties. Apples, oranges, lemons and pears all have small versions of their larger standard versions. They produce the same great-tasting fruits and the citrus trees provide the same great aromas as larger trees, all contained in a small space. Dwarf fruit trees are excellent for older individuals, or those with physical limitations, because they are easier to reach for harvesting and care. Know your USDA hardiness zone and what trees work in your area. Certain fruits, such as apples, require particular climates to succeed and produce. Apples need 1,000 to 2,000 cold hours in order to develop the best fruit. Citrus normally prefers warm winter climates, but some recent developments created strains that are more weather resistant. A great benefit of dwarf citrus trees, however, is the ability to plant in containers that you can bring in during cold weather and keep indoors.
Self-fertile apple trees include Braeburn, Cox, Spartan, Sunset and Barmley. These trees do not require another individual in the vicinity in order to reproduce and are the best bets for small spaces.
All dwarf citrus trees pollinate themselves. This makes things much easier than in the past, when lone trees needed hand pollination in order to produce fruit.
Hazelnut trees are small enough to fit in a small garden. You'll need at least two, planted close together enough for pollination from wind, and the trees need a colder climate for winter cooling. When planted in the right environment, hazelnut is a short, broad and vibrant green addition to a small garden.
Cherry trees are a naturally small, standard tree that works well in small garden areas. Morello, Stella and Sunburst are small dwarf cherry trees that self-pollinate. You can add one of each for a variety, or if you are really pinched for room, you only need one to give you delicious, big, red cherries.
A less common but delicious fruit that is great for small spaces is the pomegranate. It tolerates extremes in temperature on both ends of the spectrum and is ornamental as well as delicious. Pomegranate is high in cancer-fighting antioxidants, too.