DO YOU KNOW THIS ARBORVITAE?

We know you know all about arborvitae, but do you know how we know? It’s because we see them everywhere! What you may not know is that there are some close cousins within the family. Cupressaceae (Cypress) is a broad family with many notable members, such as the Redwoods (Metasequoia, Sequoia, Sequoiadendron), Bald Cypress (Taxodium), Cryptomeria, Arborvitae (Thuja), False Cypress (Chamaecyparis), and Juniper (Juniperus).

A wonderful plant to add to your hopefully expanding pallet is a much lesser-known cousin, Thujopsis dolabrata, or “False Arborvitae,” sometimes called Hiba or Hiba Arborvitae. What is interesting about this plant is the less-than-stellar reviews it gets in the Dirr manual and the misleading descriptions from the Missouri Botanical Garden. This highlights the importance of local knowledge of a plant vs. broad sweeping references. Don’t get us wrong, both sources are authorities on plant materials, but they are written through geographic lenses.

Let’s start with what this plant is. Upon first glance, it looks just like what you picture when you think “Arborvitae.” In fact, continued on page 22 continued from page 20

Thujopsis is from Greek – opsis meaning resembles – as in this plant resembles Thuja. Perhaps you will notice that the leaves are a little wider, or a bit deeper-green in color, but it is a tough ID. Native to central and southern Japan, this plant is found deep in the forest, growing in consistently moist, deep soils of higher organic content. They are fully winter hardy in zone 5 and will maintain their deep green throughout the winter.

The straight species is a large tree, reaching into the 50-foot range (100 on native sites in Japan), and spans about half that in width. We’ll discuss some great cultivars in a bit.

We’ve had one of these at the Funai Arboretum for some time and have loved it, but during a fall visit to a private garden guided by our great friend Bill Hendricks, this plant took on a whole new meaning in our understanding of proper plant placement and use.

Dotted across this private garden (acres in size) were specimens of Thujopsis, in a few cultivars, planted in varied sites. Some in deep shade, some in full sun, but all in deep soils that don’t get too dry during the summer. We found that while many references state to keep this plant in full sun to part shade, specimens in the deep shade of this decadesold garden looked equally as stunning.

Seeing these beautiful plants had us wondering a couple of things. One, why does Dr. Dirr say this plant “isn’t worth the commercial effort” and two, why don’t we have more of them in our own gardens?

Dissecting the first question, it’s a simple answer. The landscape industry isn’t asking the nurseries for this plant and the nurseries are pushing this plant. So, WAKE UP CALL, we all need this in our landscapes! The answer to the second question is even easier, we want too many plants for our allocated budgets!

That being said, let’s investigate the more common cultivars you need to be either growing, or buying this season.

‘Aurea’ is a smaller shrub form of False Arborvitae, settling under 8 feet… and it will take quite some time to get there. Its foliage is very splayed out, giving this shrub a ferny texture which features gold/yellow highlights through the summer. We would place this one in full to part sun and enjoy the yellow in the foliage. Deep shade won’t allow the highlights to fully develop.

‘Koreanum’ is a bit larger, reaching into the 10-to-15-foot range and about two-thirds in width. This beauty will be at home in deep shade and seems to form a more conical shape (in the shade), versus a more rounded top in full sun. Think for a minute, this is a solid evergreen, great for screening, that is happy in full sun to full shade – literally a must have plant.

‘Nana’– like all nanas out there – is a dwarf cultivar, coming in at around the 3-foot range. This plant makes cute little green meatballs (without the ugly sheering effect) and fits perfect in a conifer collection, or your typical homeowner’s landscape. No pruning ever, no clean up ever, no real pest issues – just a perfect evergreen ball!

‘Variegata,’ as expected, is a variegated form, again in the 10-to15-foot range and just slightly less in width. The variegation is a near pure-white and makes a stark contrast to the deep green of the plant. Like ‘Koreanum,’ this plant is good to go in all light conditions and makes a great accent. Or, you can mass them up at the back of the border to build a perfect living fence.

We promise, this is a plant to start asking for if you are a landscaper and absolutely one to grow and sell to your clients for our nursery friends. Need one more reason? How about the deer seem to leave them alone and there are practically no real pest or disease issues!