Mulching and Weeding - Small seedlings sprout everywhere, so periodic weeding is necessary where they are unwanted. A layer of organic mulch 2 to 4 inches thick keeps the soil moist and should take care of any serious weed problems. First lay down some landscape fabric and cover that with a mulch such as chopped leaves or wood chips out to the tips of the branches (drip line). Keep the mulch about 6 inches away from the trunk to avoid stem rot and rodent damage. Avoid mulching with un-chopped leaves because they mat together, preventing water from soaking into the soil. Peat moss makes poor mulch, because it draws water from the soil like a wick and is difficult to rewet when dry. If you don t mulch, be careful with weeding tools, to avoid damaging the tree s root system. It s best to hand pull weeds growing close to the tree. You can control hard-to-kill perennial weeds by spot treating with a fatty acid soap herbicide or a glyphosate herbicide, both of which are biodegradable. If you splash the foliage with the chemical, rinse it off with water.
Elms need watering most when they re first planted, during droughts and in late fall before the ground freezes.
Elms need only one application each year of fertilizer such as commercial sludge, fertilizer with a slow release form of nitrogen, or compost. Spread the granular fertilizer on soil to 1-1/2 times the distance from the trunk to the tips of the branches, and remember more isn t always better! Be sure to read the package directions carefully to determine the correct amount to apply. Encourage hardening off for winter by stopping any feeding 2 months before first frost.
Pruning your young American Elm tree is important to develop a strong well-shaped tree. Pruning needs to be done 1-3 times a year during the first few years of growth. Train young Lacebark Elms one of two ways - to a single leader that begins branching at about 12 feet, or to a lower multi-branched form with limbs starting about 4 feet above ground level. Shorten excessively long branches.
On established trees prune broken or rubbing branches of all Elms in late winter. If you have an American Elm, avoid pruning it from July through September, studies have shown it makes them more disease-prone. Remove and destroy diseased American Elm wood immediately, as bark beetles that carry the Dutch Elm disease breed in the dying and broken branches. Cut back roots that threaten to dislodge sidewalks or disturb underground pipes. -