The answer to how deep plant roses depends on your climate and rose type. In cold zones, plant grafted roses with the bud union 2-4 inches below soil level. In warm zones, keep the bud union at or just above ground level. Own-root roses go at the same depth they grew in their pot.
Getting the rose planting depth right protects your plant for years to come. I learned this after losing two grafted hybrid teas during a harsh winter. I had planted them with the bud union above ground like the nursery tag said. That advice was wrong for my cold climate.
The next spring, I planted new roses with the bud union buried 3 inches deep. Those roses made it through the next winter just fine. They've now been in my garden for eight years and bloom better every season.
The bud union depth roses need relates to how grafted roses grow. The bud union is the swollen knob where your fancy variety was joined to tough rootstock. This graft point is the weakest part of a grafted rose. If it freezes, you lose your named variety.
Colorado State says to bury grafted roses 2-4 inches deep in cold climates. Missouri Extension says 2 inches deep works in northern zones. This depth protects the bud union from freeze-thaw cycles that crack and damage plant tissue.
Warm climate gardeners have different concerns. When you bury the bud union too deep in mild zones, suckers from the rootstock can take over. Keep your bud union at soil level or just above in zones 8-10. This lets you spot suckers early and remove them before they drain energy.
Find your bud union by looking for the bulge between the roots and canes. It looks like a swollen knob and sits at the base of the main stems. Mark this spot with a piece of tape before planting so you can measure the depth as you fill the hole.
Own-root roses have no bud union to worry about. Plant these at the same depth they grew in their container. Look for the soil line on the stem and match it to your garden soil level. Going deeper won't hurt, but there's no benefit either.
Dig your planting hole twice as wide as the root ball and just as deep as you need. Set your rose in the hole and lay a stick across the top to check the depth. Adjust until the bud union sits at the right level for your climate before filling in soil around it.
Read the full article: When to Plant Roses for Beautiful Blooms
