George's Current Ramblings and Readlings

Why So Many Japanese Maples Are Dying

July 21st, 2020

   Japanese maples have never been one of the easier plants to grow.

This Japanese maple never lost its foliage last year and has now died.

   The coveted cut-leaf types are especially finicky with their thin leaves and low tolerance for lousy soil and less-than-ideal sites.

   But this season,  and really the past two years, have been particularly troublesome to this widely planted specimen small tree.

   I’m hearing widespread reports from gardeners all over who either are worried by struggling Japanese maples with lots of dead branches or dead trees altogether.

   Gardeners are especially concerned because Japanese maples are so slow-growing and therefore so expensive.

   Unfortunately, the three main explanations for the glut of maple mayhem are largely out of our control. All are related to erratic weather.

   No. 1 goes back to the past two growing seasons, when we’ve had some record-setting rain dumpings. Those caused soggy conditions in poorly drained planting sites.

   Since Japanese maples aren’t fans of “wet feet,” it doesn’t take long for roots to start rotting in wet clay. Maples also are prone to several root-rotting diseases, which are encouraged in wet weather.

   With compromised root systems, that sets trees up for potentially fatal problems when other stresses come along.

   Cause No. 2 is one of those other stresses. We had an extended warm spell in early fall, followed by a sudden nosedive into freezing territory.

This weeping Japanese maple never turned color in fall. The leaves went from in-season red to brown and hung on most of winter.

   The problem with that is it shocks branches that haven’t yet fully prepared for winter cold. The most obvious result is trees whose leaves go from growing-season color directly to brown and then hang on.

   That happens when leaves aren’t able to go through the normal progression of gradually shutting down chlorophyll, then turning color, then “pushing” off the leaves by sealing off where the leaves attach to the stems (a process called “abscission”).

   With unsealed leaf attachments, trees can lose additional moisture over winter, which can kill roots.

   That’s happened in three of the past four falls, thanks to our increasingly wacky weather in a changing climate.

   Cause No. 3 was the real finishing blow.

Taking It to the Bank

July 14th, 2020

   Planting a steep bank is one of gardening’s worst challenges.

This is part of the bank nightmare as I found it in winter.

   When the bank is covered in weeds, pock-marked with rocks the size of riding-mower engines, and obscured by poison ivy, wild grape vines, and wintercreeper vines growing 40 feet up half-dead trees, it’s more nightmare than challenge.

   That’s what I faced in my new Pittsburgh back yard, which for some reason seemed like a doable challenge at buying time a year or so ago.

   Neighbors told me the previous owners seldom ventured outside, and other than a once-a-year leaf-raking, didn’t do any yard maintenance in the eight years they lived there.

   The huge bank across the whole back yard certainly showed it. The bank runs more than 100 feet across and 30 to 40 feet up, with a slope angle of about 45 degrees… enough to easily slip on (which my bruised elbows will verify).

   After a year of brutal labor, I’m getting it under control. I thought I’d share what I’ve done in case others of you have similar banking problems… or just enjoy a good horror story.

Why It’s SO Important to Get Watering Right

July 7th, 2020

   I hope you’re staying on top of the garden-watering.

Even toddlers know it’s important to water the new trees!

   Yeah, water is expensive, and watering the plants eats up a lot of time. But the alternative in a dry, blistering July spell like this can be even more costly in terms of dead plants.

   When temperatures rise into the 90s day after day, plant water needs go up with it. The heat itself adds to plant stress.

   Your job as plant caretaker is to make sure plants get enough water that they don’t dry and die in this outdoor furnace.

   Don’t get faked out by the quick-hit storms we often get in summer. Those can be fakeouts on three fronts:

   1.) They’re spotty. It’s entirely possible for one area to get a two-inch dumping but then nothing falls two blocks away.

   2.) Summer storms often look like they’re delivering more rain than they really do. I can’t tell you how many times I’ve seen heavy winds and seemingly heavy rains roll through, only to find a quarter-inch or less of water in my rain gauge.

   3.) Rain can come down so fast that more of it ends up in the sewer system than around the hydrangea roots.

   What really counts is how much moisture is in your soil where your roots are.

   Those 10-minute downpours often deposit only enough water to wet the mulch or to penetrate the lawn surface – just enough to keep the grass from going brown and crunchy. That’s why it’s not a good idea to let the color of the grass act as your “rain gauge.”

   You can’t always go by wilting plants as your guide either.

   For one thing, by the time plants wilt, most of them are already suffering growth setbacks.

   For another, plants sometimes wilt for reasons other than lack of water. Flat-out excess heat is enough to make big-leaf hydrangeas wilt during the day, for example. You can tell the difference first thing in the morning. If the leaves have recovered, the plant probably has enough soil moisture. If they’re still wilted, the plant likely needs water.

   A third problem is with needled evergreens. They can look perfectly fine for weeks after their roots have completely died from lack of water. Then they suddenly brown all over.

   That happens because conifers are good at holding moisture and color in their foliage long after the water flow from the roots has stopped. Think about how your Christmas tree stays green for weeks after it’s been completely severed from the roots.

   It’s way too late to do anything once an evergreen has browned. The time to water was weeks ago when the soil went dry.

   Fourth – and most ironic – is that plants can wilt from too much soil moisture.

   I’ve heard from several people so far this summer who overdid it with the watering and caused root death.

   One fellow told me he was losing a pair of new Hinoki cypresses because his landscaper told him to “dig a moat around the plants and fill it three times a day.” That amount of water led to soggy soil, which deprived the roots of oxygen and basically started “suffocating” the plants.

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.

“Zooming” the Grass Away

June 23rd, 2020

   A little virus named Covid-19 changed the way the whole world works.

My first Zoom talk is going to be on replacing grass.

   One of the changes has been in how we communicate in group settings.

   Whether it’s a teacher in front of a class or a speaker at a conference, the whole concept of group talks got swept away overnight.

   To fill the void, a lot of groups switched to online talks called “webinars” – Internet-speak for seminars via the web.

   Lots of companies offer ways to do this, but one that’s really caught on – from virus-isolated family meet-ups to corporate conferencing – is Zoom. The company’s name has even spawned a new meaning of an old verb, as in, “Do you want to zoom next Thursday?”

   The gardening world has been doing a lot of zooming lately since the pandemic shutdown came at a time when gardening talks, seminars, and conferences are normally in peak mode.

   All of my spring talks simply got axed, but I’m going to be doing my first Zoom talk on Thur., Aug. 27, from 7 to 9 p.m., for Phipps Conservatory in Pittsburgh.

   I had originally contracted to do an in-person talk on “Goodbye Grass” in the Conservatory’s Botany Hill with a book-signing and refreshments beforehand.

   With the likelihood of coronavirus sticking around at least for the foreseeable coming months, Phipps’ staff and I agreed that Zoom might be a better way to go.