Most trees should outlive you. If a landscaper tells you the lifespan of a tree is 10 years, they don't know what they're talking about.
Trees are free. Carefully comb over your yard for baby trees, especially in mid-spring!
Similarly, If you live near a gravel driveway or gravel parking lot, you can find baby tree sprouts that can be easily transplanted by gently removing the gravel bits from around the roots, wrapping the roots in wet paper towel, and transplanting to a large pot.
Do not pile up mulch around the base of a tree. You can mulch under the tree, but it should be a mostly flat layer, not a raised mound, and keep the mulch a few inches away from touching the trunk. Roots need some access to air or the tree will grow roots upward through the mulch, and the roots will slowly wrap around the trunk and strangle the tree to death. It's called root girdling and it is very sad.
Trees need friends!!! If possible, plant two or three trees instead of just one. Trees share nutrients through the mycorrhizal network and they protect each other from storm damage.
Always get a tree that is native to your area and suited to your local environment.
Growing an oak from an acorn is easy. Go to an area where there are oaks in the fall, and collect the acorns that have turned brown and whose hats have popped off. Get large pots at least 8 inches depth, and lay the acorns on their sides on top of the potting soil, then cover them with a layer of damp fallen leaves, and leave them outside all winter long. Just be sure to cover them with some wire mesh or something to protect them from squirrels
Please keep oaks and other large trees about 20 feet from any structure because they will grow huge. Websites will tell you to keep trees X distance away from "structures or other trees" but other trees can go as little as 6-10 feet apart whereas structures need to be like 15 feet away minimum, generally speaking
Prune the tree while it's dormant, NOT in the middle of summer!
If you happen to be from the Eastern United States, please consider getting an oak! They are keystone species and host plants for literally hundreds of insects. We have too many maples here too, so maybe consider a Sweetgum or Black Gum for pretty fall colors?
If you have a tree that's tied to a stake to keep it upright, get rid of that thing as soon as you can, particularly if there's zip ties holding it to the tree, because those can grow into the bark and kill the tree...
If your tree is dead, please consider cutting off the branches and leaving at least 6-10 feet or so of trunk standing. Dead tree snags like this are important nesting places for many birds and you might see a woodpecker
If you live in North America, whatever you do, do NOT get anything marketed as an "ornamental flowering pear tree." They're typically Pyrus calleryana, and they're virulently invasive
Bugs eating a few holes in the leaves of your tree? Good for them! (They aren't hurting the tree unless they're like, fully skeletonizing it, and they're just the caterpillars of butterflies and moths. Want Luna moths or Tiger Swallowtail butterflies? Let the caterpillars eat their dinner mmkay.)
Don't throw away the fallen leaves! Butterflies, moths, stick bugs, lightning bugs, ladybugs, and many other insects hibernate the winter in the fallen leaves. Use them as mulch for flower beds, compost them, or just leave them alone! You'll probably want to stop mowing after the leaves fall if you'd like to see bugs.
