Hybrid Tea Roses: Plant the Graft Union 4 Inches Below to 1 Inch Above, by Zone

Plant a grafted hybrid tea so the graft union sits 2 to 4 inches below the soil line where winters are hard, and level with the soil or about 1 inch above it where they’re mild. Iowa State and Colorado State Extension both say 2 to 4 inches below; the University of Georgia says 1 inch above. Each is right for its own winters, and the gap between them is what this guide sorts out.

The union is the knob where the named cultivar was budded onto a separate rootstock. Penn State Extension says that if it’s compromised, “the part of the plant above that graft union will die,” and whatever regrows from below is the rootstock, not the rose you paid for. In warm, wet soil the risk flips: Oregon State Extension notes that planting too deep invites disease at the graft. We compared eight extension pages on this question, and they disagree more than any competing article admits. Iowa State’s planting guide says 2 to 4 inches; its hybrid tea FAQ says 2 to 3.

Why the graft union is the weak point of a hybrid tea

The graft union is the one spot on a hybrid tea where a single cold night can erase the cultivar. Hybrid teas are bred for one large, high-centered bloom on a long stem, and most are sold grafted: a bud of the named variety is joined to a rootstock chosen for vigor. K-State Extension says the union normally sits “just at, or below, the soil level” and warns that “if the plant is killed at this junction, the desirable rose is lost” (K-State Johnson County). Iowa State describes the knob as vulnerable to severe cold and temperature swings, which is the logic behind burying it: soil moderates both.

Rootstock choice is regional. In Florida, roses grafted on Fortuniana grow larger, flower more and live longer than other roses, and UF/IFAS Extension in Charlotte County ranks Fortuniana first, ‘Dr. Huey’ second and ‘Multiflora’ last for lifespan there. UF/IFAS’s Gardening Solutions guide is blunter: “Any grafted roses should be on Fortuniana rootstock.” If you garden in Florida, ask the nursery which rootstock your rose is on before you ask anything else.

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Anything growing below the union is a sucker from the rootstock. The UC Master Gardener Program says to remove suckers “as close to the root stem as possible” instead of snipping them at the soil line. Own-root roses sidestep the whole issue: they’re grown from cuttings, so if the canes die back, Penn State says new ones “will often emerge from the rose’s deep roots” and they’ll be the same cultivar. In zones 3 and 4, an own-root hybrid tea is the lower-risk version of this plant if you can find one. Check the label or ask.

Graft union depth: what eight extension pages say

Across these pages, the recommended depth falls steadily as winters warm: 4 inches below the surface at the cold end, level with the soil or 1 inch above at the mild end. The table lists every page we read, in order from coldest to mildest.

Three things explain why the numbers disagree. First, the winters differ. Oregon State draws its own line at 20°F: where winter lows predictably drop below it, bury the union 1 to 2 inches; where they don’t, keep it above the soil. Second, depth and mounding are partly interchangeable. Penn State protects a grafted rose with a foot of mound, while K-State pairs a shallower union with a 6 to 8 inch cone, so a lower depth number doesn’t always mean less protection. Third, burying has a cost in mild climates. Oregon State says planting too deep there risks disease at the graft.

Treat the figures as ranges with about an inch of give, not exact requirements. Iowa State’s two pages differ by an inch for the same crop in the same state. That’s our reading of the evidence rather than a finding from any one page.

The sources also collide across zones 7 and 8, which is where many readers garden. By USDA’s half-zone bands, zone 8a averages a 10 to 15°F winter low and zone 8b 15 to 20°F, so Oregon State’s 20°F line would put all of zone 8 on the buried-union side. Georgia, a state that straddles the zone 7 to 8 range, recommends the union 1 inch above the soil. Nobody has tested hybrid teas against both rules side by side, so the chart below picks a compromise for those zones and says so.

Hybrid tea graft union depth and winter protection by zone

For USDA zones 5 and 6, plant the union 2 to 3 inches below the soil and mound 10 to 12 inches over it after the first killing freezes; in zone 8, set it level with the soil to 1 inch above. The chart below is our synthesis of the table above, and the last column says how solid each row is.

Read these as bands, not lines on a map. A zone 6 garden on an exposed hilltop behaves more like zone 5, and a sheltered courtyard in zone 5 can behave like zone 6. If your plant is in the cold half of its band, take the deeper number. For month-by-month work in your own zone, see our guides to growing roses in zone 5, zone 6, zone 7, zone 8 and zone 9, or the colder-climate versions for zone 4 and zone 3.

How to plant a hybrid tea at the right depth

Find the union first, then dig the hole to fit it, not the other way around. Iowa State says the hole should be “deep enough to accommodate the root system and bury the graft union at the appropriate depth,” and describes the union as the knob or crook in the stem. Here’s the sequence:

1. Locate the knob. It’s the swollen joint at the base of the canes. If your rose doesn’t have one, it’s probably own-root, and the crown goes 1 to 2 inches below the soil line per Colorado State.
2. Dig wide, then check the depth. Lay a shovel handle across the hole so it marks the soil line, then measure down from it. That’s a practical trick of ours, not an extension rule.
3. Bare-root roses: build a cone-shaped mound of soil in the center of the hole and drape the roots over it, as Iowa State describes. Plant in early spring before growth starts. Colorado State adds that keeping the canes from drying out is the most important step in dry climates, and that loose, moist soil can stay mounded over the canes for 2 to 7 weeks.
4. Potted roses: Colorado State’s rule is the same as for bare-root: the union goes 2 to 4 inches below ground level in its climate. Don’t copy the depth the rose was growing at in the nursery pot unless your climate matches that rule.
5. Sun and water: UConn puts the minimum at 6 hours of sun daily. Water the new rose in well, and keep the soil line where you set it as the soil settles.

A pair of long rose gauntlet gloves makes the planting and the later pruning far less painful (affiliate link; we earn a commission on qualifying Amazon purchases at no cost to you). For the full bare-root routine, including soaking and timing, see our bare-root rose planting guide, and for the other planting errors that cost roses a season, common rose-growing mistakes.

Winter protection: mound, Minnesota Tip, or nothing

Wait until several hard freezes have killed the leaves, then pile 10 to 12 inches of well-drained soil or compost over the base. UNH Extension says to “avoid applying winter protection until hard frosts have killed any remaining leaves,” and NDSU Extension wants the rose “completely dormant after several hard freezes,” then another foot of leaves or straw once the mound freezes. Mound heights climb with winter severity: K-State’s cone is 6 to 8 inches, UNH and NDSU use 10 to 12, and Penn State aims for about a foot over a grafted union. That scaling is our reading of the pages. None of them states it as a rule.

Bring the soil in from elsewhere. K-State says to haul it to the plant rather than rake it up from around the base. (Our guess at the reason: scraping soil from beside the plant bares the roots you’re trying to protect.)

The Minnesota Tip Method is the coldest-zone option. NDSU’s steps: tie the canes together with soft fabric, apply fungicide, dig a trench beside the base, loosen the roots on the opposite side, tip the plant into the trench, remove soil from the crown, cover it, and add a foot of leaves or straw once the soil freezes. It’s labor, but it buries the whole plant instead of just the knob. Skip the foam rose cone. NDSU says it “traps moisture that can lead to rotting” and can heat up on sunny winter days enough to wake the plant early.

Don’t prune hard in fall. UNH warns that heavy fall pruning “could mean loss of the entire plant in the event of a severe winter” and suggests leaving 18 to 24 inches of healthy cane under the mulch; K-State cuts hybrid teas to about 24 inches. Uncover in spring just before growth begins (K-State), or when lows stop dipping below 20°F (Penn State), whichever your climate hits first.

Blackspot and powdery mildew: the other way hybrid teas fail

Most hybrid teas are highly susceptible to blackspot, according to Iowa State Extension, so disease resistance is the second thing to choose after planting depth. The fungus needs about seven hours of leaf moisture to infect, with development fastest at 75 to 85°F and high humidity, and it overwinters “in fallen leaves and lesions on canes.” In practice, a leaf wetted by an evening sprinkler can stay wet past that seven-hour mark. That’s an inference from the 7-hour figure, not a measured result. This is also why you rake up fallen leaves before you mound for winter.

Powdery mildew behaves differently, and the two diseases give opposite watering advice. The Pacific Northwest Plant Disease Management Handbook says mildew spores germinate best on nights with high humidity or heavy dew near 70°F, can develop on dry leaves as long as the air is humid, and are actually burst by flowing water or rain. The way through is timing: water at the base in the morning so blackspot is less likely to get its seven wet hours, and if mildew is the bigger problem, a strong spray on the foliage in early afternoon lets the plant dry fast. The handbook says that reduces mildew but doesn’t eliminate it.

The first two rows are diseases; the rest are planting and protection mistakes that look like disease. Telling them apart saves a season of spraying the wrong problem.

Hybrid teas with real blackspot data behind them

Thirty hybrid teas were tested for four years in Shreveport, Louisiana, and five came out ahead. The LSU AgCenter and American Rose Society Easy-Tea trial ran from February 2009 to October 2012 as a replicated, randomized study, and its five “Easy-Tea” designees were chosen on blackspot susceptibility plus overall landscape performance.

One more rose, Tiffany, ranked 5th for blackspot resistance but wasn’t an Easy-Tea designee. Read the results with three caveats. The roses got four fungicide applications a year, so this is a minimum-spray trial, not a no-spray one. Two of the four years were dry, which lowers blackspot pressure. And the PNW handbook warns that roses resistant in one place “may be susceptible in another due to… different fungal strains,” so a Louisiana winner is a starting list for gardens elsewhere, not a guarantee. The trial also says nothing about cold hardiness, which is a separate question from disease. For wider variety choices by ease and fragrance, see our rose types compared by ease and fragrance, and for the disease side in depth, our rose diseases guide.

If you spray, read the label on a copper fungicide before the first application (affiliate link). Iowa State’s interval is every 7 to 14 days.

Pruning for one big bloom per stem

Prune hybrid teas hard in late winter or early spring, down to 18 to 24 inches. UConn says hybrid teas “usually require more severe pruning” than other roses, and the UC Master Gardener Program adds that “lower pruning (especially hybrid teas) produces longer stems and larger blooms.” The UC rule of thumb is to prune one foot lower than the full-foliage height you want. K-State notes by comparison that shrub roses need minimal pruning, which is why a hybrid tea is the higher-maintenance choice. Our complete rose pruning guide covers the cuts, and a sharp pair of bypass pruners makes clean slanted cuts above an outward-facing bud (affiliate link).

If a hybrid tea’s maintenance load is more than you want, the usual alternative is a shrub rose. Our guide to English roses that rebloom to frost covers the varieties, and the full picture of rose care across all types sits in our rose care guide.

Frequently asked questions

How deep should I plant a hybrid tea rose?

Plant the graft union 2 to 4 inches below the soil in cold climates, about 1 to 2 inches below in the middle zones, and level with the soil to 1 inch above in mild ones. Iowa State and Colorado State say 2 to 4 inches below, UConn says about 1 inch below, and Georgia says 1 inch above.

Should the graft union be above or below the soil?

Below in places where winter lows predictably drop under 20°F, above where they don’t. That’s Oregon State Extension’s rule, and the other pages in our table fit it as a rough pattern.

What happens if I plant a hybrid tea too deep or too shallow?

Too shallow in a cold climate exposes the union to freezing, and if it’s killed, the named rose is lost, per K-State and Penn State. Too deep in a mild climate risks disease at the graft, per Oregon State.

Do hybrid tea roses need winter protection in zone 7?

Usually yes. Zone 7 winter lows run 0 to 10°F, well under Oregon State’s 20°F line. A 6 to 8 inch soil cone, as K-State describes, is the lighter end of the protection range. Penn State’s protocol covers zones 5a to 7b.

Which hybrid tea roses resist blackspot best?

In the LSU AgCenter’s four-year Shreveport trial, The McCartney Rose, Traviata, Pink Traviata, Tahitian Sunset and Tiffany ranked highest for blackspot resistance. The plants still got four fungicide sprays a year, and results can differ by region.

How do I tell a rootstock sucker from a branch of my rose?

Anything growing below the graft union is a sucker. Remove it as close to the root stem as you can, rather than cutting it at the soil line.

Sources

1. Iowa State University Extension and Outreach. How to Plant and Transplant Roses — Yard & Garden, updated February 2025. Iowa State University
2. Iowa State University Extension and Outreach. What is the proper planting depth when planting hybrid tea roses? — Yard & Garden FAQ, updated December 2024. Iowa State University
3. Colorado State University Extension. Selecting and Planting Roses — reviewed August 2025. Colorado State University
4. Pettinelli, D. Start Now For a Rosy Summer — April 25, 2024. UConn Home & Garden Education Center
5. K-State Research and Extension, Johnson County. Winter Care for Hybrid Tea and Shrub Roses — updated June 2026. Kansas State University
6. University of New Hampshire Extension. Winter Protection of Roses [fact sheet] — updated November 2016. University of New Hampshire
7. NDSU Extension. Dakota Gardener: Winter protection for tender roses — October 24, 2024. North Dakota State University
8. Marquesen, S. Protecting Your Roses through Pennsylvania Winters — November 15, 2023. Penn State Extension
9. Oldfield, S. Plant rose bud union above or below the soil? — Ask Extension, March 25, 2021. Oregon State University Extension
10. Westerfield, B. and Florkowska, M. Roses in Georgia: Selecting and Growing Techniques, Circular 1001 — reviewed July 2026. University of Georgia Extension
11. UF/IFAS Extension. Flowers: Roses — Gardening Solutions. University of Florida
12. Mitchell, R. E. Gardening can be rosy — UF/IFAS Extension Charlotte County, November 25, 2020. University of Florida
13. Iowa State University Extension and Outreach. Rose Black Spot — Yard & Garden, reviewed April 2022. Iowa State University
14. Pacific Northwest Plant Disease Management Handbook. Rose (Rosa spp.) and hybrids — Powdery Mildew, March 2026. Oregon State University, Washington State University, University of Idaho
15. Benedict, L. F. and Owings, A. D. Finding Lower-Maintenance Easy-Tea Hybrid Tea Roses — Louisiana Agriculture, Summer 2013. LSU AgCenter
16. Mowery, L. Pruning Rose Bushes — UC Master Gardener Program. University of California Agriculture and Natural Resources
17. USDA Agricultural Research Service. How to Use the Maps — USDA Plant Hardiness Zone Map, 2023 edition. U.S. Department of Agriculture