Hetz’s Japanese holly does not grow fast and can take several years to mature. The ‘Hetzii’ cultivar usually tops out at around 6 feet. But in some cases, this Japanese holly bush can grow up to 8 feet tall, though you can keep it small with pruning. The best time to plant it is in the spring or fall. Take care when planting, as saponins in the shrub are toxic to people and pets. Also, note that Japanese holly is considered invasive in certain areas, so check local regulations prior to planting. Holly shrubs are dioecious, so if you have your heart set on berries, you will need to grow a male to pollinate a female shrub. However, because Ilex crenata ‘Hetzii’ is specifically a female cultivar, you can’t just go out and get a male Hetz to complement it. You must use a male of a different type of Ilex crenata, such as ‘Bee Hive’, ‘Hoogendorn’, or ‘Rotundifolia’. Although pollen can travel some distance, experts recommend planting one of these males close by to improve your chances of pollination. This shrub generally has minimal pest and disease problems. But occasionally, spider mites and nematodes can infest it.
Light
Hetz’s Japanese holly can take full sun, meaning six hours of direct sun on most days, but it also can grow in partial shade. It can struggle in heat, so afternoon shade in hot climates can be helpful.
Soil
This shrub can tolerate a range of soil types, including sandy and clay soils. A well-draining loamy soil that’s high in organic matter is ideal, along with a slightly acidic soil pH.
Water
Hetz’s Japanese holly’s water requirements are moderate. A consistently lightly moist soil is best, but the shrub should not sit in waterlogged soil. Mature shrubs have some drought tolerance.
Temperature and Humidity
Hetz’s Japanese holly is not a fan of hot, humid climates. But it does have fairly good resistance to the cold temperatures of its growing zones.
Fertilizer
Japanese holly doesn’t need an excessive amount of fertilizer. But you can feed it annually in the spring with a slow-release shrub fertilizer to support healthy foliage growth.
Types of Japanese Holly
Besides ‘Hetzii’, there are several other types of Japanese holly:
‘Helleri’ is a dwarf, mounding type. ‘Golden Helleri’ offers golden foliage. ‘Sky Pencil’ forms a striking column. ‘Lemon Gem’ has yellow foliage that matures to a lime green color. ‘Dwarf Pagoda’ is another dwarf variety that only reaches around 2 feet tall.
Pruning
In general, you can lightly prune this shrub anytime from spring to fall to tidy up its growth and remove any dead or damaged portions. Stop pruning roughly two months prior to your first expected fall frost. More substantial pruning should be done in the late winter or early spring prior to new growth picking up.
Propagating Hetz’s Japanese Holly
Hetz’s Japanese holly can be propagated via stem cuttings. This is an easy and inexpensive way to create a new shrub, and it allows you to create more of this particular cultivar. The best time to take a cutting is while the shrub is dormant over winter. Here’s how:
Potting and Repotting Hetz’s Japanese Holly
Thanks to this shrub’s slow growth rate, it can do well in a container for quite a while until it needs to be transplanted into the ground for more space. While Hetz’s Japanese holly doesn’t have very deep roots, they will ultimately outgrow the space of even a large container. When first potting, opt for a container that’s a couple inches wider and deeper than the root ball of your nursery shrub. Make sure it has drainage holes, and consider unglazed clay for your container material to allow extra soil moisture to evaporate through the walls. Once you see roots growing up out of the soil and down out of the drainage holes, you’ll know your plant is root-bound and needs repotting. Carefully ease the plant out of its old container, gently tease apart the roots to help them spread, and replant it in either a larger container or the ground.
Overwintering
If you live in the coldest parts of this shrub’s growing zones, you can improve its chances of remaining healthy through winter by adding a thick layer of mulch around its base.
Common Problems With Hetz’s Japanese Holly
Hetz’s Japanese holly typically grows with few issues. However, if its environment isn’t right, some problems can arise.
Leaves Turning Yellow
This shrub’s evergreen leaves should remain a rich green until they ultimately depreciate at the end of their life cycle. However, soil that is too alkaline can cause the leaves to yellow. If you spot yellowing foliage, get a soil test done and then amend your soil if necessary based on its results.
