Whether tree roots will continue to grow after a tree has been cut down depends on the species. Some tree roots will eventually die because they can no longer get nutrients through photosynthesis. However, other species that reproduce through root sprouts can continue to grow and produce new sprouts for seven years or more. For example, the roots of elms, ficus, and willows tend to regrow aggressively, while the roots of pines, oaks, and maples will typically die. To determine if a root system is still active, look for new sprouts on the old trunk, stump, or any exposed roots.

While there is a lot of debate about whether boiling water is strong enough to kill tree roots, it is not best to remove the roots from large, old trees. You may be able to weaken young roots enough to remove them manually, but boiling water will likely not do the trick for large root systems.

Generally, you’ll want to prune back the trunk by 1 to 2 feet each year to promote bushy growth. Doing so concentrates vegetative buds closer to the bottom of the tree, where you can easily harvest fruit. For side shoots that are a year old, leave at least six leaves. 

Never remove more than 30% of a tree’s foliage during pruning—even if your tree is really overgrown. Removing this much foliage at a time could kill your tree.

Generally, you’ll want to avoid pruning more than 25% of the tree’s canopy at one time. While pruning your tree is important, it’s possible to do it too often or to go too far. Again, this is why hiring a tree trimming pro to do the work is wise. However, if you do decide to DIY, going slow and trimming gradually is the name of the game.