The berries and leaves of ‘Blue Princess’ holly are are toxic to humans and pets.
In the warmer parts of its hardiness range, it should have protection from the harsh afternoon sun.
Soil
Well-drained soil is key for these shrubs.
The Spruce / Evgeniya Vlasova
This will establish an extensive root system.
Just double-check it’s never waterlogged.
Temperature and Humidity
The lowest temperatures this plant can endure are about -20 to -10 degrees Fahrenheit.
The Spruce / Evgeniya Vlasova
Prolonged exposure to unseasonable heat or cold can weaken or kill it.
Mulch can help to insulate the roots against temperature extremes.
It’s also ideal to plant the shrub somewhere that is sheltered from harsh, drying winter winds.
The Spruce / Evgeniya Vlasova
A moderate humidity level is ideal.
Fertilizer
Minimal fertilizer is required for this shrub.
In fact, too much nitrogen in the soil can keep ‘Blue Princess’ from fruiting.
The Spruce / Evgeniya Vlasova
Use an organic fertilizer made especially for holly, following label instructions.
It’s also beneficial to mix compost into the soil at the time of planting.
Thebest time to prune hollydepends on aesthetics.
The Spruce / Evgeniya Vlasova
To accomplish this, stagger the depth of your cuts.
Hollies bloom on old wood produced the previous growing season.
So remember that the later you prune, the fewer flowers and berries will be produced the following year.
For ‘Blue Princess’ holly, growers in zone 4 and 5 should consider some form of winter protection.
Disease issues include a variety of fungal problems, including powdery mildew, leaf spot, and tar spot.
Water at the base of the shrub rather than with overhead spraying to reduce fungal spore transmission.
These hybrid shrubs are sold under various male and female cultivars.
‘Blue Prince’ is a male pollinator paired with the female version, ‘Blue Princess.’
With Blue Princess holly the goal is not flowers, butfertilizedflowers that will lead to attractive red berries.
Feeding with an acid fertilizer can counteract this if you have highly alkaline soil.
Mulching with pine needles can also help acidify the soil.
Prevent future episodes by regularly treating the shrub with a fungicide.
Burned Leaves
Browned leaves and dead branches are most commonly due to winter injury.
Remove the dead leaves and trim back the branches to green wood.
With proper care and growing conditions, most holly shrubs are capable of living 100 years or more.
If your shrub is producing the hallmark red berries, then you know it is female.
North Carolina State Extension.
