A 2 or 3-inch layer of some attractive organic mulch offers many benefits to trees. Spread wood chips, chopped leaves, shredded bark or a similar material in a circle directly on the soil under the tree.
Larches do not require routine pruning. If it is necessary to remove injured or diseased branches, it is best to prune in mid-summer.
Larches are most comfortable in moist soil. Of course, as with all new transplants it is important to water them when they are newly planted. Also, during times when rainfall is irregular and drought conditions prevail, even mature, well-established larches appreciate supplemental watering. Check the soil under the tree. If it is dry down several inches, run a drip system or sprinkler for minutes or so every week to 10 days until rain falls.
Do not fertilize larches until they have been in place at least a year. Then an annual light feeding of a granular all-purpose fertilizer is recommended. Sprinkle it on the soil under the tree, out as far as the branches extend for the rain to soak in. Use 1/2 pound of fertilizer for each 1/2 inch of trunk diameter, measured at the base.
While larches are able to handle very cold winters, they are vulnerable to wind damage in the first three or four years in the ground Protect young larches that are exposed to wind with a screen of burlap or the white spun agricultural fabric that admits air and light, but will block harsh winds. Do NOT use plastic of any kind, because it will cut off all air around the tree. Add an inch to the summer mulch over the roots of the tree.