Start with about 1 inch (2.5 cm) of water a week, rain included. Iowa State University Extension gives that as a garden baseline, and when the rain falls short, you make up the rest. From there you adjust by species and by season. Watering evergreen trees is less about a set number than about soaking the root zone deep, and often enough that it never bakes dry.
It is the third week of November and I am dragging a hose down the north edge of my own lot, where the row of spruce runs. No rain since the first week of October. The soil is cold, but it still drinks, and that is the whole reason I am out here in a coat. Roots keep growing until the ground freezes, so a dry late autumn is the worst possible time to coil the hose and call the season finished. I give each tree a slow half hour. I set the hose at the next tree, go inside, and come back out when the coffee is gone.
Where the water lands matters as much as how much you pour on. Most of the feeding roots, the ones that take up water and nutrients, sit in the top 6 to 18 inches (15 to 46 cm) of soil, and they spread far wider than the branches do. A quick pass with a sprinkler wets the first inch and burns off by noon. Run the hose at a trickle instead, leave it in one spot long enough for the water to sink in, then shift it a few feet and repeat around the tree. Dig down a few inches when you are done, and keep going if the soil under the surface is still dry.
Species set the rest of it. Spruce and fir want extra water and do well in an irrigated lawn, while pines and junipers do better on drier ground and resent being watered like turf. That split is the practical half of evergreen water needs, and it should shape your planting plan and not just your hose schedule. Group trees with similar needs together in one bed. A blue spruce set next to a juniper leaves you picking which one to disappoint every time you water.
Winter watering evergreens comes down to one long soak before the ground freezes for good. Needles keep losing moisture all winter, and on a bright windy day in January a tree can dry out with frozen soil under it and no way to pull up more. Sending the root zone into winter wet reduces that desiccation injury. Do it in late fall on a day above freezing, and give the water a few hours to move down before dark. Dry autumns are the ones that do the damage, so put this at the top of the list after a rainless September.
More water is not always the fix, and that is the part of watering evergreen trees people get wrong. Both drought and soggy, poorly drained soil cause abnormal needle drop, so browning inside the canopy does not mean you should double the hose time. Dig into that root band near the drip line before you decide anything. Damp soil under dropping needles points at drainage, not thirst. Dry soil at that depth means you are behind and need to catch up. That one check saves a lot of trees from being drowned by an owner trying to help.
The routine that works is the one you can keep. Work from the 1 inch a week garden baseline through the growing season, counting whatever the sky hands you. Put it down slow and deep rather than fast and shallow. Extra for the spruce and fir. Less for pines and junipers once they have settled in. One last long drink before the ground locks up, and that covers watering evergreen trees for the year.
Read the full article: Evergreen Trees: 8 Types and How to Choose
