They say that the best time to plant a tree was 20 years ago, but since we don't have an app for time travel yet, we'll have to focus on planting during the second best time, which is right now. And you don't have to have a massive lot or backyard in order to plant trees for food, shade, or beauty, as there are many tree varieties that remain small enough to not crowd or shade out everything else, and which can function as either the canopy layer or the sub-canopy in permaculture-style plantings even in a smaller space.
Here are 10 great tree varieties for small yards and gardens:
A number of species of Amalanchier, or serviceberry, are available, with varying heights ranging from shrub-sized to small tree, and with some producing a delicious blueberry-like fruit after the fragrant white flowers are pollinated. Also called saskatoon, juneberry, shadbush, or sugar-plum, serviceberry trees also produce a flash of fall color when their leaves turn, and can thrive in a wide variety of climates.
2. Crape Myrtle:
Sometimes referred to as the "lilac of the South," crape (or crepe) myrtle (Lagerstroemia) trees are well-suited to full sun locations, are heat tolerant, and produce showy flowers even in poor soil. A variety of sizes of crape myrtle are available, from a compact shrub to a 30-foot tree, with flowers ranging from white to fuchsia, and with an "exfoliating" bark that offers winter contrast.
Although the flowering dogwood (Conus florida) is the most commonly seen kind of dogwood, there are a number of other varieties of dogwoods, ranging from shrub-sized to tree-sized, but most will thrive in moist, shadier locations. With showy flowers in white, pink, or red, dogwoods can add a burst of spring color to the yard, and certain species, such as the Korean dogwood (Cornus kousa) produce an edible fruit, while other species' fruit is more suited to the wildlife.
4. Japanese Maple:
Acer palmatum is a fairly common landscape tree, and with good reason, as its small stature and bold colors can be a great accent in a little space. Japanese maple trees come in hundreds of varieties, with a wide range of leaf types, growth habits, and colors, but most of them are best suited for partially shaded locations, and although the flowers are rather modest, the fall leaf color of these trees can more than make up for that. Although the fruit (samara) isn't edible, according to The Spruce, the Japanese sometimes fry the maple leaves to make candies.
The source of the common astringent named after it, witchhazel (or witch hazel) grows as a small tree or a large shrub bearing fragrant yellow or orange-red fall or winter flowers (which is why it's also sometimes called winterbloom). With several species commonly available, and many cultivars, witchhazels come in a number of sizes and shapes, and as the Chicago Botanic Gardens says, "the only major drawback to witch hazels lies at their roots—a preference for well-drained, loamy, acidic soil means that they grow less than happily in clay soil."
Elderberries (Sambucus) are most often seen as shrubs, although varieties that grow more like a small tree are available, and their flowers and berries are good for pollinators and other wildlife, while the fruit is also prized for making jam, wine, pies, and other delicacies. According to Garden.org, elderberries "grow best in a slightly acidic soil that is high in organic matter and stays consistently moist," but that is well-drained, and are suited to full or part-sun locaions.
Although a full-sized apple tree might overwhelm a small yard, dwarf apple trees can stay at or under 8 feet tall, while still producing a good-sized crop of full-sized fruit. There are literally thousands of varieties of apple trees, many of which are grafted onto dwarf rootstock, which keeps the trees smaller, while upper portion (the scion wood) determines the quality and type of fruit. From sweet early summer apples to late season keeper apples, there are apple varieties for just about any eating preference, and while some dwarf varieties can still grow larger than intended, judicious pruning can keep them in check. Many common fruit trees are available in dwarf sizes that would fit a small yard, such as peaches, apricots, pears, cherries, and more.
There's nothing quite like a ripe fig, right off the tree, and although figs seem like they're only for Mediterranean zones, there are fig varieties that can be successfully grown in a number of different climates, and in small spaces. Fig trees can be cultivated in protected areas in some northern climates, and can even thrive in pots or containers, which can then be brought inside or sheltered during the winter, and in contrast with other fruit trees, can benefit from heavy pruning each year to keep them to size.
The chaste tree, or monk's pepper (Vitex agnus-castus), is a multi-trunk small tree with clusters of fragrant purple flowers and lacy gray-green leaves. The fruit resembles a peppercorn and is used in alternative medicine, and the flowers are a favorite of butterflies, bees, and people alike. Vitex grows best in full or part-sun locations with well-drained soil, and can aggressively invade nearby soil in the right conditions. According to folklore, the tree was named so because it was believed that it was an anaphrodisiac, with medieval monks having chewed its leaves to help them maintain their vows of celibacy.
Redbud trees, which can actually have white, pink, red, or purple flowers, are a staple showy spring treat in the garden, and although some can grow 20 to 30 feet tall, can be a good addition to a smaller yard or garden, especially with some careful pruning. Redbud seeds are good forage for wildlife, and redbuds are said to be an important source of nectar and pollen for honeybees and other pollinators. This fast-growing tree prefers well-drained soil and full sun to part shade, and because it's in the pea family, can get some of its nitrogen from the air so that only light fertilization is necessary.
This list of trees for small yards is just a jumping off point for choosing the best varieties for your situation. These are commonly available trees, so if increasing biodiversity is important to you, other varieties that aren't widely available commercially or that are native to the area but not often seen in yards could be a much better choice. The local climate needs to be taken into consideration, as well as any specific space and height constraints, before getting too far down the rabbit hole of looking at tree catalogs and nursery stock. With hundreds thousands of choices of species and varieties available, there's a tree or shrub for just about any location, and the best guidance can come from local gardeners, orchardists, and arborists, who have hands-on experience, rather than just buying what looks good on an impulse. One great resource is this post on Backyard Orchard Culture.