Water for young trees in dry country

Put drip on a newly planted fruit tree the day you plant it and keep the root zone from ever drying out: a deep soak at least once a week, twice a week in summer heat, daily to every other day on sand. In zone 4 and colder, start tapering in mid-August, stop by late August, and give one last deep drink after the leaves drop. Drip is how every tree we plant in Montana gets its water for its first three years, swales or no swales, and a shovel is the best moisture meter you'll ever own.

The first-year rules

One deep watering a week is the minimum; two in summer heat is better. The rest of our rules, with reasons from our friend Bob Purvis of Homedale, Idaho:

1. Deep means wetting the whole root zone. Young trees need about half the water of mature ones, Purvis says, given more often and for less time.
2. Sand needs more trips. Clay holds much more water, so sandy ground gets watered more often and for shorter spells so water doesn't run past the roots.
3. When in doubt, give more rather than less, unless you have heavy clay or it rains all the time. In all our years we've seen one overwatered tree, and a burst pipe had it standing in water. Granted, this is Montana.
4. Keep the grass back. Weeds are "first in line for water and nutrients," so Purvis says to keep a circle 3 to 4 feet across clear for the first 3 to 5 years. We use mulch.
5. Water wider each year. Roots "will not explore dry soil," and after the first year they spread well past the branch tips. Move the emitters out with them.
6. Never let it get dry in the first place. A dry root zone stops the shoots and the roots, and dried-out topsoil and mulch can turn water-shy, so rewetting takes more water and more time than keeping it moist would have.

A bare-root tree needs 6 to 8 weeks to establish roots (Purvis), so keep the hole moist through that stretch.

Earthworks don't water trees

If you build swales, keyline rips or planting basins anywhere in Montana or the dry West, put drip on the trees anyway, for the first three years at least. Earthworks bank spring water in the ground, and that's worth doing. They don't reach a first-year root system in July. Missoula's normals are 14.11 inches a year, 0.85 in July and 0.83 in August, and MSU's Western Agricultural Research Center says apples "require around 20 inches" of water in a growing season and that in the Intermountain West "trees left unwatered will die." The people who built the earthworks movement irrigate their new plantings too. Brad Lancaster in Tucson: "You typically need to irrigate the newly planted plants for 1 to 3 years to get their root system growing well and established." The Greening the Desert project in Jordan "needs irrigation during the dry season," in its own words. MSU calls drip "the preferred method" for new orchard trees, and so do we.

Why drip, and why a hose isn't irrigation

A garden hose runs about 13 gallons a minute (Utah State). Spread over a 3-foot basin that's roughly 178 inches of water an hour, against the 0.2 to 0.4 inches an hour a loam can take in (NRCS). The rest runs off, ponds, or goes down a crack, and fast water on dry ground slakes the surface into a crust that sheds the next watering too (NRCS). Most hose waterings are also far too small: wetting just the top foot under a young tree takes about 4 gallons in sand, 7 to 9 in loam and 11 in clay (from Texas A&M's rule that an inch of water wets a foot of sand), and a ten-second splash puts down 2. Dry soil has one more trick. Once it dries below a critical water content, organic coatings on the particles make it shed water, so it "may simply pool on the surface or may move down preferred pathways, leaving large amounts of soil dry even when a large volume of water is applied" (University of Florida). That water repellency has been documented on unburned ground in the Bitterroot Valley, and it rises with organic matter, so a dried-out mulch and duff layer is the layer to watch. Anyone who has watered a bone-dry houseplant and watched the water run straight out the bottom has seen the same thing: dry peat shrinks from the pot wall and is hard to rewet (Clemson). A drip emitter run for hours puts the water on slowly enough to soak in, keeps the leaves dry, and never lets the root zone reach that point. Run the emitters under the mulch, and move them out as the roots spread.

Why we don't buy "deep and infrequent"

You'll read in many bulletins that trees should be watered deeply and seldom so the roots go down looking for water. We're skeptical, and most of the establishment research we've found points the other way. A young apple quits growing under water stress too mild to measure: in a study of second- and third-year trees, "Growth cessations occurred in mild water stress conditions before any difference in stem water potential appeared" (Chen and colleagues, 2019). Roots don't go looking, either. Purvis's line is that roots "will not explore dry soil," and Michigan State's Bert Cregg puts it this way: "roots do proliferate where resources are available." Colorado State's schedule for new trees is daily for the first week or two, every 2 to 3 days through week 12, then weekly, with the warning that "Larger volumes of water applied infrequently may result in drought-stressed roots," and WSU waters young trees one to three times a week in warm weather. The studies that show deeper roots with less water are about mature trees on deep soils getting less water in total. Deep and often aren't opposites. On drip you get deep by running long at a slow rate, and often because a young root zone in sand or gravel holds about a day of water and in loam a few days. Clay and silt hold more and can go a week; organic matter adds less storage than the sales pitch says (WSU). Keep the root zone moist, not wet: over-irrigation "slows root growth, increases iron chlorosis in alkaline soils" (Utah State), and Purvis warns of root rot.

How to tell if a tree is thirsty

Dig down and feel. Our best advice on watering is to develop your internal calibrator: push a shovel into the root zone and see whether the soil is moist or dry. Most of a fruit tree's roots sit in the top foot of soil, some in the second and fewer in the third (Purvis), so check down there, not at the surface. Dry soil is hard to rewet, so don't let it get that far.

The tree will tell you too:

• Terminal buds setting early. A young tree that stops growing and sets buds at its shoot tips in June or July is short on water. Purvis explains why: a tree that dries out slowly, short of the wilting point, reacts by setting a terminal bud.
• Short growth. Purvis looks for 16 to 24 inches of new growth a year on apple trees that aren't bearing yet. If it isn't there, he says, look at your watering.
• Droop that lasts. In hot, dry weather, Purvis notes, even well-watered trees can't move water to their leaves as fast as they lose it in the afternoon, then recover overnight. If the droop is still there in the morning, water.

How much water, and how to measure it

More than you'd think in July. We don't have our own Montana figures, so here are Purvis's numbers for a mature apple orchard in Washington State:

Purvis says orchard foremen typically water too much in spring and sometimes not enough in summer, and the table shows why. At 0.25 inch a day, rain plus irrigation has to supply 1.75 inches a week. Young trees need about half. Even apricots, which Purvis ranks among the most drought-tolerant fruit trees, do better with extra water in arid country.

To see what a sprinkler actually puts down, use Purvis's method: set out tuna cans marked in tenths of an inch and read them afterward. Use one with a fairly flat spray, not an oscillating sprinkler that throws water high, because wet leaves promote scab, mildew and brown rot. In hot wind, water at night; more of it reaches the trees.

Drip or flood

Drip is how every tree we plant gets its water for its first three years. It puts water on the root zone slowly enough to soak in and keeps it off the leaves, the same reason Purvis warns against oscillating sprinklers.

Flood irrigation is the other end of the scale, and it's Luke's specialty: he designs flood-irrigated tree crop systems, and our mission talks about systems that are "drought proof/water abundant." Darren Doherty, the Australian keyline designer, prefers flood outright. Keyline Design Mark IV, which he wrote with Abe Collins, calls drip tape a vegetable method that uses a lot of plastic, says "slow irrigation drowns soil aerobes," and describes keyline flood irrigation covering up to eight acres an hour with one person running it. That's a big-farm view. Our line is that flood comes after drip, not instead of it: drip for every tree for its first three years, then flood for established trees on ground that holds water (clay-rich or silty), with ditch water and the right slope. On gravelly, low-organic-matter calcareous benches, flood water runs through and past the roots the way it runs through a dry pot, and drip stays the tool.

Either way, don't let roots sit wet. Purvis warns that roots kept waterlogged for long stretches can die of root rot.

The August shutdown

In zone 4 and colder, start tapering the water in mid-August and stop by late August. We know it may be hot then. But first frost may be a month away and serious sub-zero cold two months off, and the tree has to shut its metabolism down and harden off, which matters most in its first few years.

One more inch of growth isn't worth it. A terminal bud in June means thirst; in August it's what you want. Purvis notes young trees tend to grow later into fall than mature ones. In late October 2020, Missoula went from mild fall weather to -10 to -20F almost overnight, and it wiped out a lot of trees rated plenty hardy on paper because they hadn't gone dormant yet (more on our cold hardiness calculator page). It's the same reason we don't feed through the roots into July.

Make the last drink a soak, not a swamp. Our zone hardiness guide puts it bluntly: wet feet going into winter kill more trees than cold does.

Read the land first

Look at where water wants to go before you plant a tree. P.A. Yeomans, the Australian engineer behind keyline design, ranked what shapes a farm by how hard it is to change: climate, land shape, water supply, roads, trees, buildings, fences, soil. Soil comes last because deep living soil is, in his words, "more of a goal than a constraint of design and planning." Darren Doherty's Regrarians Platform stretches that list to ten layers, adding economy and energy, and his shorthand is "You have to be blue before you're green and black," meaning water, then plants, then profit. Mark Shepard puts earthworks and water ahead of trees at New Forest Farm in Wisconsin.

Keyline in plain words

Find where a valley's steep upper part flattens out; Yeomans called that the keypoint. Work the ground parallel to a line through it, and each rip line runs slightly downhill from the wet draw toward the drier ridge, spreading water that would otherwise pile up low. Regrarians lays out tree rows on the same pattern, about 52 feet apart. Done properly, Doherty says, it makes a swale "largely redundant," though he allows for one sitting right on a valley's keyline.

These are design ideas we like, on modest evidence. An Ontario trial found keyline plowing did nothing for soil organic matter, though "the subsoiled plots held more moisture than the control," and a British Columbia trial found a single keyline pass did not appear to increase infiltration. Keyline was never a no-irrigation system, either: Yeomans caught runoff in dams so he could flood-irrigate below them. Rip before you plant, since subsoiling beside trees root-prunes them (Savanna Institute). Collins and Doherty make the same point from the other side: "Keyline soil development on pastureland prior to tree establishment will accelerate tree growth."

Where to put trees relative to water

On the slope, below your water and above your cold air. Cold air is heavy: on clear, still nights it runs downhill like water and pools in low ground, so the low spot where water collects is where frost settles too. In the 2026 bloom frost, growers up on the benches and higher on the valley floor fared much better than those down low. Purvis puts it plainly: plant on a slope, "but not at the top of a windswept hill, nor down in a valley," and the leeward side of a pond or other water is excellent.

Water stored above the trees can reach them by gravity, the way Yeomans set up his farms. Then match the tree to the water you can get to it. Dwarf trees have small root systems and need more diligent watering (Purvis). Bud 118, which carries about 90 of our apples and crabs, is a rootstock he calls appropriate for droughty soils, and he says standard-size trees suit ground that's dry and can't easily be watered.

Mulch, ponds and small-scale flood

Mulch keeps the water you already put down from leaving. Purvis says it reduces moisture loss and keeps the soil cool, and our planting guide calls for "copious amounts," hardwood by preference. Mulch also replaces the grass that would drink first: Washington State University notes cover crops compete with young trees for water, and Purvis notes roots spread much further in a bare strip than under sod.

A pond above the orchard is the small version of Yeomans's farms: catch water high and let gravity move it. Shepard sizes a pond from the catchment area feeding it times the inches of the biggest rain event. Keep trees off the dam; Regrarians warns that "trees should not be allowed to grow on an embankment that is holding back water." Ask the Montana DNRC about water rights before you dig.

If you flood, keep the sets short and let the ground drain between them. On heavy, calcareous ground that matters twice, since MSU lists saturated soil, along with high pH and bicarbonate-heavy water, as causes of iron deficiency.

Related guides

• What to do when your bare-root trees arrive
• Feed the soil, not the tree
• Winter protection for young fruit trees

Where this comes from

• Our planting guide, About page, rootstocks page, zone guide, hardiness calculator and notes.
• Bob Purvis's lecture notes on home fruit growing (water management) and on apricots.
• P.A. Yeomans: The Keyline Plan (1954), The Challenge of Landscape (1958) and Water for Every Farm.
• Darren Doherty: the Regrarians Platform; Keyline Design Mark IV, with Abe Collins; his comments on swales.
• Mark Shepard: Restoration Agriculture (2013) and Water for Any Farm.
• RAIN Algoma's keyline plowing trial (2015); the Savanna Institute's Perennial Pathways (2017).
• Montana State University (Growing Fruit Trees in Montana, EB0222; the Western Agricultural Research Center's apple irrigation guides) and Washington State University Extension.
• NRCS soil quality sheets on infiltration and slaking; Utah State, Colorado State, Texas A&M, University of Florida and Clemson extension pages on watering and soil water repellency; Brady, Robichaud and Pierson (2001) on water-repellent soils in the Bitterroot Valley; Chen and colleagues, Annals of Botany (2019); Bert Cregg, Michigan State; WSU's Andrew McGuire on organic matter and water.
• Brad Lancaster, harvestingrainwater.com; the Greening the Desert Project, Jordan; the British Columbia keyline trial (2018 report); NOAA 1991 to 2020 climate normals for Missoula.

Updated September 2026.