Can Someone Please Invent This Plant?

June 30th, 2020

   There’s usually at least one suitable plant for any planting situation.

Evergreens can thin out like this in shade.

   But I have nothing to tell the guy who emailed me looking for an evergreen he can use to give dense privacy in the shade of his mature trees.

   Jim said he had tried interspersing ‘Green Giant’ arborvitae (an excellent plant) but found they lost their denseness under the canopy of his 60- to 70-foot-tall maples.

   He wanted to know if there was another option for something that would give year-round dense screening in the woodland shade and filtered light – something that’s also fast-growing and resistant to deer.

   “Is there any such evergreen?” he asked.

   Not that I know of. If you do, let us both know. Or get to work breeding something because you’ll make a lot of money.

   I suspect many people run into this dilemma. I can think of a few suggestions, but none that are ideal.

   Back in the good old days, I’d have recommended hemlocks. These natives with the soft, flat needles aren’t particular deer favorites, they do pretty well in shade, and they stay fairly dense, too.

Woolly adelgids have infested this hemlock.

   But twenty-something years ago, a bug called woolly adelgid came along to devastate the species. The problem has leveled out in recent years, but adelgids still pose enough of a threat that there’s a good chance they’ll find hemlocks and either thin them out from their chlorophyll-sucking damage (which undoes their screening benefit) or kill them outright.

   Breeders at the U.S. Agricultural Research Service have managed to come up with a new cross between the Southern native Carolina hemlock and the Chinese hemlock that’s resistant to adelgids. However, the variety, named Traveler, isn’t in production yet, is at least years away from being on the market, and might be borderline winter-hardy in central Pennsylvania.

   Upright yews are tough, dense, cold-hardy, and reasonably shade-tolerant, but deer love them.

   Upright Japanese plum yews? Deer don’t care for them, but they’re so columnar in habit that you’d need a ton of them three to four feet apart to do any kind of screening.

   Jim’s ‘Green Giant’ attempt was a good one because deer don’t like that form of western arborvitae nearly as much as our native eastern ones like the popular ‘Emerald Green’ variety. I’ve seen them do OK in part-day shade, but as Jim found, they really don’t do well in deeper shade.

   A big part of the problem is that most conifers (pines, spruce, firs, etc.) are full-sun plants in their native environments. They tend to colonize open meadows and hillsides and don’t compete well as under-story plants when bigger deciduous trees go up and above them.

   When we try to insert conifers in that situation, they quickly thin out from lack of light. They also usually run into stunted growth in general from the combination of shade and roots from the nearby shade trees.

   I’ve seen spruce trees, cryptomeria, and Hinoki and goldthread/greenthread falsecypresses hold their own for a while in a setting like Jim described. But in the long run, they thin out, too.

   Japanese umbrella pines are somewhat shade-tolerant, but they’re extremely slow-growing and too expensive for mass-planting.

   Leyland cypress, junipers, and pines are even more sun-demanding than arborvitae.

   Broad-leaf evergreens work a little better.

Camellias are excellent shade-tolerant screening evergreens — in the South.

   If we were warm enough to grow camellias, that would be a good solution, although they’re not terribly fast growers. Southern gardeners turn to these rosy-blooming beauties as their go-to screening evergreen in shade.

   We might get by with some of the hardier varieties of camellias, a la the April and Winter’s series, but I’ve seen polar vortexes knock them back to the ground every so often. They’re not a lock in the long haul.

   Ditto for aucuba, photinia, osmanthus, and some of the taller laurels, like skip and Portuguese types. They’re decent options in the slightly warmer Philadelphia and Baltimore/Washington areas, but we often get just a little cold and windy that the foliage gets beat up in winter. Or they die in our cold, wet clay soil over winter. Photinia and many of the laurels also are susceptible to disease.

   Both taller American hollies and the bushy blue hollies are somewhat shade-tolerant, but they get thin in time – and believe it or not – deer often eat the leathery, spiny leaves of hollies (American hollies less so than blue hollies and hybrids like Dragon Lady).

   Deer don’t like boxwoods, and these are somewhat shade-tolerant, but most of them are short. The taller ones are skinny, so like upright Japanese plum yews, you’d need a ton of them to make a difference in the woods. Plus there’s the new boxwood-blight issue to be wary of.

   Cherry laurels are some of the hardiest laurels, but they don’t get much taller than four to six feet. Plus deer like them.

   Nandina? Too little.

   Rhododendrons are shade-tough and can grow upwards of 12 to 14 feet, but deer like them even better than cherry laurel and holly and at least as much as eastern arborvitae and yews.

   I’m out of possibilities.

   Rather than try to force an unwilling or unable plant into an unhappy situation, maybe it’s possible to plant a line or staggered double row of conifers in a sunnier spot in front of or in back of the wooded area?

   If that’s not possible, maybe erecting a fence is a better idea. You wouldn’t necessarily need a huge one – just in the line of the view you’re trying to block.

   For that matter, do you need a shed? I know of some people who put up a shed more to block a view than to store tools.

   Like I said, someone needs to come up with a new plant…