The Many Ways I Could’ve Failed on My Driveway Bank

August 23rd, 2022

   Did you ever feel like the deck was stacked against you on a yard project?

   All the time, eh?

   For me, I got that feeling when I started tackling the 60-foot-long, steep bank that lines my driveway.

   This area was a mess when we bought the place.

   Earlier owners obviously gave up because what we inherited was a forgotten tangle of weeds, flopped-over ornamental grasses, dead shrubs in various stages of decay, and layers of fallen leaves that had been piling up and rotting for years.

   Yet the area was big and prominent – readily visible from the street and the first view when entering our home land.

   I’ve been working on it for four years now, and although it’s not completely “solved,” the driveway bank is at least now more of a “landscape” than a “wasteland.”

   I thought it might be helpful to others of you facing challenges – at least this particular kind – if I went over some of what I did to overcome the problems, which include awful soil, big tree roots, runoff issues, weeds, varying degrees of shade, and above all else, deer.

   Any one of those could’ve caused big-time failure.

   Here’s how I sidestepped failure (so far)…

Runoff

   Problems with this had to be addressed before even thinking about planting.

   In heavy rain, runoff from the properties above was coming down the slope forcefully enough to cut channels in some spots while flowing down in sheets elsewhere, leading to erosion.

   To deal with the most concentrated area of runoff, I sunk a couple of catch basins higher up to collect the water and direct it through about 100 feet of plastic drain pipe from Lowe’s that I laid. I had to dig and bury some of it, but most I laid on top of the ground to cover later.

   Step two was installing sections of stone retaining walls, which created three levels of terraces. The idea of those was to break up the sheet runoff and allow water to soak in.

   The drain pipe got covered when I backfilled the walls with purchased topsoil.

   Step three was lining the top of the slope with a two-stone layer of retaining wall. The idea there was to discourage water from running down the slope in the first place, directing it along the top of the slope and out to the street’s storm-sewer system instead.

   If that sounds like a lot of heavy-duty labor, it was. Most people would’ve hired out the work. I would have, too, if we hadn’t already spent our savings on pressing repairs to the house.

   But without getting the deluges under control, planting the bank would have been a colossal mistake.

Lousy soil

   Soil on slopes is typically thin because of erosion.

   That’s what I was starting with, except what I had was heavy clay. I hit bedrock just a few inches down.

   This situation was another factor in why I decided to build the terraces. By bringing in backfill behind the terraces, that would allow much better soil depth for plant roots.

   The mistake I made was not investing in a higher grade of soil. I bought a dump-truck load of “topsoil” from a local landscape-supply company that assured me “it was pretty good.”

   By “pretty good,” I think that meant that it just wasn’t loaded with trash, debris, and rocks.

   The topsoil looked OK coming out of the truck and was “clean,” but I quickly realized the quality of it wasn’t much better than the clay I already had.

   The upshot is that I’ve had to improve the soil with my own homemade compost, with bulk leafmold compost from the borough, and with store-bought mushroom soil.

   Despite what researchers might advise about trying to stick with native soil, I’ve seen a marked difference between what I’ve planted in unimproved soil vs. what I’ve planted in generously enriched areas.

   If I were doing this over again, I would’ve sought out topsoil already blended with compost or similar organic matter.

Weeds

   One of the worst drawbacks of long-ignored beds is that the soil very likely has been banking up an enormous quantity of weed seeds.

   Not only is it a royal headache to get rid of established weeds, but those dropped weed seeds from years of neglect will germinate with abandon in the cleared, disturbed, and watered soil of a newly planted bed.

   I’ve been battling this issue throughout my whole property, driving home the lesson of how important it is to get weeds under control and keep them under control with regular vigilance. After years of doing that in my previous Cumberland County home, I had virtually no problem with weeds.

   Out here in Pittsburgh, I pull one set of weeds and soon get another. It’ll be years before the weed-seed bank goes broke. I’m working to make “withdrawals” while preventing new “deposits.”

   On the slope, I greatly reduced an immediate weed rebellion by mulching. For round one, I used wood chips that came from several dead trees that I had cut down and ground up.

   Round two the following year was a couple of inches of shredded hardwood, which knits together nicely to hold in place on grades.

   I’ve supplemented that with routine weed patrols and regular yanking while the weeds are young and easy to pull.

Big tree roots, variable light, and deer

   I’m lumping these three together because the solution to each revolves mainly around wise plant selection.

   Any one of the above issues is capable of killing or at least badly stunting plants if you pick the wrong thing.

   Some plants are pretty good about dealing with adversities, but others need very specific conditions to survive and thrive.

   In this case, I was dealing with multiple adversities. That meant I not only had to cross off anything with specific needs but anything unlikely to handle my “big three” hurdles (“big four” if you count the bad soil).

   I started with the deer problem. As anyone who’s gardened in deer country knows, there is no such thing as a “deer-proof” plant. A starving deer might eat anything, including spiny hollies and roses with thorns.

   The really maddening part is that deer aren’t consistent in what they eat and when.

   Neighbors might tell you a certain plant is “safe” because they’ve been growing it for years, but when you plant the same thing, it gets eaten to the ground.

   Or a plant you’ve been growing openly for years suddenly gets chewed one cold winter or rubbed to death by a buck who was focused on antler-itch-relief and not hunger.

   The saving grace, though, is that despite being such heavy and rampant feeders, deer are actually picky eaters… when they’re not starving.

   That gives us gardeners a fighting chance if we choose low on their favorite-plant list – or at least lower than what your neighbors have planted.

   That’s the tack I took. Using Rutgers University’s excellent “Landscape Plants Rated by Deer Resistance” list, I zeroed in on shrubs, evergreens, and flowers on the lowest rung of the deer menu.

   I’ve also been using deer-repellent sprays at the most vulnerable times, taking into account that young plantings are particularly susceptible to deer browsing.

   The second big hurdle relates to the two big pin oak trees growing on the slope. Big oak trees have big roots, and those pose tremendous competition for any new plant.

   Over the years, I’ve found that some plants are much better at competing with established tree roots than others.

   You can’t just go by species that are OK with the shade. Azaleas, rhododendrons, leucothoe, Japanese holly, and mountain laurels are among those that I’ve found are shade-tolerant but that struggle to establish when they’re inserted into beds under mature trees.

   So in this area, I had to whittle my plant list down to ones that are unlikely to be eaten by deer and good at coping with dry shade and root competition.

   I’ve had to really stay on top of watering everything in the early going. Those big trees suck up moisture in a matter of days, so I’ve had to soak new plantings twice a week during hot, dry spells (which have been happening more than I’d like this year so far).

   One lesson that gardeners too often learn the hard way is that even the drought-toughest plants aren’t very drought-tough until their roots have had a chance to colonize. That means even they need regular water for at least the first year or two after planting (and three to four years for trees).

   As for light, the uppermost part of the bank is away from the roots and shade, meaning that area needs plants tolerant of heat and sun.

   Complicating things further is the fact that the oaks are limbed up, allowing near full afternoon sun to shine into the west-facing part of the oak area.

   I spent the best part of my first year just watching where the light hit, at what time of day, for how long, and what the combination of heat/light/roots did to the soil moisture.

So what did I end up planting?

   With all of the above “reconnaissance” in hand, it was time to figure out what I should plant on the bank – if anything was left!

   One thing I’ve learned in 45 years of gardening is that there’s at least one plant that will thrive in every spot. It might be a weed, but clever nature has devised cheatgrass for sidewalk cracks and lupines for Iceland’s cold, barren lava fields.

   In the dry-shade-and-roots area, I’ve had five ‘Mt. Airy’ fothergilla, four Korean spice viburnums, three dwarf weigela, and groundcovers of variegated Solomon’s seal and pachysandra all survive. (I’m not a fan of pachysandra, but I caved in because of cost, future reduction in mulching, and fast coverage in addition to its passing my big-three-hurdle test.)

   This spring, I also added a Flame Thrower redbud tree. It’s not exactly thriving like it should so far, but I’m hoping it’ll hang in there through these establishment years to survive long-term.

   A gold-variegated elderberry previously struggled there, so I’ll be watching the redbud closely – especially since it was the most expensive tree I ever bought.

   Out where the light is brighter but the oak roots are still a factor, I’ve had good luck with seven dwarf Little Henry sweetspires (Itea virginica) and five ‘Hummingbird’ dwarf summersweets (Clethra alnifolia).

   These both colonize nicely, which makes them especially good choices for grabbing onto and covering a slope.

   My two western-most summersweets struggled by August of the first year, which I took as a sign they were getting too much heat and light since the other three (in slightly less light) were doing well. So I flipped the two western strugglers to the opposite end of the planting, and now all five are doing well.

   That clue gave me good information on the dividing line between the sun area and the part-shade/root-infested area.

   I planted a ring of three Russian cypress (low, spreading, soft-needled evergreens that look like junipers) around one of the oak trees, and these have struggled a bit. One died altogether after the first winter. Another is browning now. I’ll replace that one, but one more death, and I’ll be crossing Russian cypress off my list.

   Between the colonies of sweetspires and summersweets, I added a sweetbay magnolia this spring. The young tree was doing nothing after about a month, so I dug it up, improved the soil even more, raised the planting depth slightly, and gave it a dose of fertilizer. Almost immediately, new growth appeared.

   At the sunniest end of the bank, I’ve successfully planted a pair of dwarf lilacs, a Scarlet Fire kousa dogwood tree, a pair of abelias, a reblooming weigela, three dwarf panicle hydrangeas, and a screening backdrop of three ‘Green Giant’ arborvitae.

   I’ve also added a groundcover of leadwort (a.k.a. “plumbago”) that hasn’t been a 100-percent survivor but is at least trying.

   A few hardy geraniums and catmint add spot-color to this area.

   One thing I should add about all plantings on a slope… I always dig a sort of “shelf” or mini-terrace of soil where I plant each tree, shrub, and perennial.

   This level area allows water to soak in and makes a big difference in survivability vs. planting on the sloped grade and allowing the water to run straight past.

   There you have it. I can’t say it’s been easy, and I can’t say I can now sit back and watch everything get fuller and nicer on autopilot. But it’s alive. And light years better to look at than the gruesome desolation that was there before.