Some say fall is the best time of year to plant a tree, but many garden enthusiasts embrace spring as the time to establish new roots. Autumn Ridge Nursery has more than 250 types of trees you can buy online — everything from the American filbert ($5.95) to the yellow transparent apple tree ($8.50). Another great source is Tree Heaven, where you’ll find gorgeous spring trees like dogwood ($8.99) and Japanese maple ($10.99), along with a variety pack of 10 quality trees ($24.99). Heronswood’s top tree picks include the sycamore maple ($21.95) and a birch from Nepal ($18.95) along with the glorious magnolia ($21.95). For something more exotic, consider the palm tree selection at Aaron’s Nursery. But it’s hard to top this offer from the Arbor Day Foundation: If you join the foundation for $10, you’ll receive 10 free trees. Before you start digging, consult the Plant Hardiness Zone map: That’s where nurseries categorize plants, flowers and trees according to numbered climate zones, to make sure your favorite tree is suited for your area. At Arborday.org, finding your zone is as simple as putting in your ZIP code, and the shipping schedule outlines ideal delivery windows. You can even use the handy Tree Guide to get a complete picture of almost any tree. Don’t be afraid: Most online nurseries provide a 100 percent money-back guarantee on the quality of their trees.