Gardening on a slope, or, Gardening in hiking boots, or, Who needs to go for off-trail hiking in the Smokies anyway?

Every year in a garden has something that needs to be tackled. This year’s [2016] big outdoor job was to improve our handling of flooding and mud slides from the property above us. As a result of an enormous gully washer last year—it appears we are going to see more of these with climate change—a major stone retaining wall began to show signs of stress near the house. Among many other tasks, we removed over 50 buckets of mud that had slid down to our foundation wall on the north and east sides. Although the three main culverts under the house did their job as fast as they could to handle the deluge, water and mud came within an inch of flooding our ground floor.

One of the Knox County stormwater engineers who came out to our property to take a look at our predicament suggested that the Japanese rain ladders we had put in years ago should be re-oriented in a different direction. We have done that and will also use them partially for new plantings to hold the slope of the rain ladders.

A very large snag on the northern property line that had stood dead for 18 years or more finally came down—it was the oldest of several that have died along the upper property line—and we have maneuvered pieces of it into place to also shed water towards what should be the drainage ravine. (Consider that drainage “solutions” need maintenance to continue to be effective. We have removed all wooden steps that had filled with mud, flushed out muck and debris from all of our 15” culverts underneath the house foundation, and installed many catch basins and retention ponds for the 100-year-rains that now seem to come every few years.)

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I am not a professional, certainly, but I thought you might be interested in some of what I think we’ve learned from experience at Blue Note. 

I love a very lush landscape (some would say “blowsy”—the influence, no doubt, of the great metropolitan public gardens and country cottage gardens I grew up in as a youngster) as well as good design lines; and I try to emulate what I’ve seen in different places. But, basically, the design I finally arrive at comes from being in a place, with a sense of the space, for a long time and working with what is already there, not what I might wish were there.

Of course, we could not have done any of the essential garden hardscaping without Kenneth’s expertise and hard work, and sometimes a crew of helpers, too, especially since we really cannot use almost any heavy equipment on our site. About 15 years ago when the concrete terracing and steps were first constructed, we were one of the larger employers of Lakemoor Hills neighborhood teenagers, some of whom are now established professionals in challenging fields. Every once in a while we get a letter from one of them telling us how much it meant to them to show up every day on time and learn how to do very heavy work for long hours with their hands on Kenneth’s crew. One of them even featured the experience in his valedictorian speech!

Slope gardening—or, gardening in hiking boots—in this environment is challenging but it is also interesting. There are real advantages in working under constraints; personally, I think it is harder to start a garden on a flat, blank slate.

Some lessons learned:

Use grading stakes and long boards rather than the hoses that all the gardening books tell you about to check for how a terrace line or “cut” looks from an indoor viewing window and from a distance instead of just from the proverbial “bird’s eye” view on paper. You will never view your garden, in this lifetime, with a bird’s eye.

Check horizontal and vertical placement with levels for everything, including containers; humans are comforted by those, especially in the “mayhem” of a lush natural landscape.

Remember that angles on a slope are compound rather than simple and can take a while to get right; it is worth taking the time to get it right, but sometimes it just needs to be re-done until it is: try and try again. The eye will eventually “see” what’s right, just like you can tell when a stone wants to live where you place it. (I’ve been known to get the opinion of the mailman who drives by my driveway entrance garden every day.)

Recycle pretreated lumber for planting “pockets” and peg burlap into the earth with earth staples for holding soil around plants during the time they take to take root on a slope—I call them “slope scarves.” The old lumber and burlap will rot, but by that time the plant will likely be secure and at home and holding the slope on its own.

Many American gardens are essentially “amphitheater” type gardens but think about special view slots and hiding some areas from immediate view for a surprise or to pull people in around a corner. Few people can resist a bend in the path or a curious part of a corner.

Snobs will look down their noses at common plants used en masse but don’t let that bother you if they are needed as placeholders or slope-holders. Nature abhors a vacuum and it could very well put something even worse there until your ship comes in and you’re ready with the perfect plants.

Invasive weeds are tough to deal with but they can be reduced and weakened over time; it is worthwhile learning more about their life cycles and just keeping at it. My worst: bittersweet, campsis, and mahonia. Bittersweet is supposed to be allelopathic but you could never prove that by what I see. All of the vines, of all types, were taken off all of the tall trees last year here at Blue Note Garden; you can already see them going back up on them but pruning to the ground every couple of years keeps them in check.

Every property has at least one ravine or depression that can be used for clippings and compacted brush. Wildlife love them and their organic matter enriches the place they grew in to begin with. We have a very large barred owl who visits almost every day to hunt small mammals like voles, moles and chipmunks; most often he parks himself on a low tree branch and with practiced precision dive bombs the edges of the brush piles near our two ravines.

Remember that a big advantage of slope gardening is that you can reverse the order of height. Sometimes taller plants “in front” and at a lower point on the slope look and perform better.

They’re old design rules but I also like: 1) repeat the same elements—construction materials, containers, plants—to tie different parts of the garden together; 2) a truly wonderful single specimen is terrific but otherwise groupings of 3 or 5 or 7 are more appealing (don’t worry if all 3 or 5 or 7 don’t “match”—that’s why there is the tale of the Three Bears; when I look at my Baby Bear Boxwood I remember the earnest young man who dropped a concrete block on it while the box was also young because he was trying to carry too many—a nice memory, actually); and 3) if you’re after serenity in the garden, as I am, keeping to 3 colors in your palette (if in endless shades) is also a good policy (wildly successful colorists like watercolor artist Margaret Scanlan can handle many more but most of us cannot).

If you value a particular plant, don’t move it from where it’s doing well; instead change your plan and vision to accommodate it. Conversely, move a plant from where it’s clearly unhappy until you get the right combination of soil and exposure and who-knows-what-else it really wants.

Important rule for shade gardens in general: For God’s sake, don’t put paths in sun; use the sun for garden beds and put your paths in the shade looking from the relative cool of the shade into the attractive area of plants flourishing in sun. I don’t know why so many people put their paths in sun; it is a waste and not particularly attractive either.

If you don’t have enough sun for a favorite plant that you can’t live without, buy it grown to maturity by someone who does, enjoy it for the season, and pass it on as a gift to a gardener who has the perfect conditions for it before the next growing season. They will thank you many times over!

Favorite and challenging plants here:

Entrance on Wagon – Our yews are inspired by Alice in Wonderland but I admit they are way overdue for their every-other-year pruning. I promise they will be pruned soon. We let them grow naturally but prune them gently on the drive side and like an open hand. Sadly, this past winter killed a Lonicera fragrantissima (Winter honeysuckle) that I should have propagated before it died because it was grown from a cutting of a bush at UT that was bulldozed away recently when an old building was demolished; I am told one of the UT students that now has a native nursery has it so I will try to get it again; the fragrance is exceptional. The grass in the container is little blue stem. The variegated Japanese polygonum is a weed but its color with the Blushing Pink rose is nice at this time of the year and its arching branches keep people from driving into the stone wall; it doesn’t like the heat of summer so I pull it all out then. The large shrub near the mailbox is Chimonanthus praecox (Double Wintersweet), another exceptionally fragrant shrub.

Rhodo drive – The 25 hemlocks on our property have been injected for wooly adelgid and that has lasted pretty well; for smaller ones or partial infestations I spray any oil concoction I come up with as well as a strong hose burst to shake off the adelgid tufts; I keep an eye on them. I’ve removed many of the rhododendrons that were struggling in drier spaces throughout the entire garden and now most of the healthiest ones are the very old ones along the driveway. (They are a royal pain to water in drought conditions but I do it to honor their age and persistence. I take a book out there and move the hose every 10 minutes to the next one and complain the entire time. As my reward, birds also come to drink from the water spray and they are a delight to watch. The rhodos are also overdue for a major pruning planned soon for when a Japanese friend returns from a visit home. I should also be drenching for ash borer (same chemical) because we have a couple of very large ash but otherwise I use no chemical except the very rare application of Round-up on poison ivy (covered immediately with cardboard and tarp to localize the effect).

Circle drive – Fragile, spidery strap-like lavender petals on Koromo Shikibu make it my favorite azalea. Also: the tropical-looking but honestly-native edgeworthia ‘chrysantha’; danae; sarcocca hookeriana (Himalayan sweetbox—sorry, I mistakenly referred to this as skimmia this morning—what was I thinking of?); variegated (marbled) hellebores, Christmas hellebore; Panicum ‘Northwind’ for vertical element at bottom of stairs, purchased grown elsewhere in sun. (When we remove the rotting wooden staircase we hope to move the stairway next year and make it a concrete/stone one (possibly a slope) that winds around the big rock. Kenneth calls this a typical Theresa project. One of you cleverly noticed the vigorous vine going up the old dead cedar trunk in the middle of the driveway and asked its name. It is the native Decumaria barbara, otherwise known as wood vamp. It is very nice in and out of bloom.

Wildflower areas – Every year I discover something I didn’t know I had. For 18 years I have resisted pulling as a weed a plant that had all the earmarks of a native azalea except that it did not bloom; this year it finally did, with beautiful delicate pink petals, so far unidentified. A euphorbia that came in with the birds might be a thug eventually but so far it is playing reasonably well with the other plants and putting up a fight with the vinca that is exactly what I need. I’m sure there are genuine weeds in the areas that I should be more aggressive about removing, but I don’t want to harm the rarer items. Reputedly, one of the original residents of here was something of a wildflower collector before it was fashionable and so I try to be cautious. Another find recently was a native “nodding” trillium amongst the several hundred trilliums and hepatica we have here. When wet, the resurrection fern on the big rocks is absolutely spectacular; I wish I could afford to keep it “in water” with irrigation but perhaps it is better that it makes do as the rains come. We also have a couple of small patches of cliff brake fern, which has now become very rare. Plants in the German-made window boxes on the steel beam walkway over the waterfall are in the difficult western exposure but their saving grace is that there is a water reservoir at their roots. Heuchera and sown seeds such as nicotiana and even carnation do pretty well there, supplemented by annual torenia and disease-resistant impatiens. By the end of the season, vines that would be rampant in the garden instead cascade down from the boxes for an impressive length.

Beech garden – The reason why we have adapted our living room as a more open, better lit, glassed-in “screened” porch is this magnificent tree whose roots I was too afraid to injure, even with a beam platform. It has been hard to get sedum to take hold in the gravel slope but it is finally happy and spreading. Three dwarf hemlocks moved from a location less than 20 feet away have suddenly taken on new life in the new place they obviously vastly prefer. There is a climbing Japanese hydrangea vine on the beech that, at 15 feet now, is in recovery mode after being cut down mistakenly when vines were removed last year from the trees. Before being cut it was at least 50 feet up into the beech tree and was spectacular in full bloom. On the back side of the beech is an American hydrangea vine that is much more slowly growing. I apologize for not weeding the paths and beds in this area more thoroughly; it is impossible to get the weed roots out whole from the beech roots until there is very good, soaking rain which we’ve had in short supply so far this year. A couple of you asked about the Aralia cordata in the container, ‘Sun King’ Golden Japanese Spikenard which is a contrasting color that the late blooming Hot Shot azaleas really need for brightness. The dwarf evergreen that looks a lot like arborvitae is called Thujopsis; it is rare and has taken over 15 years to get to its current 20-inch height. The yews at the back of that bed—because we want to see the Tennessee River from our living room/porch during the winter—are called Taxus Everlow and they are just that. The other evergreen in this area that is nearly prostrate is Cephalotaxus harringtonia ‘Prostrata’ and it is very fine in every respect.

Maple and hydrangea garden – Maples on our northeast exposure suffered this winter/spring from late cold winds, with most others fine. Half of the big umbrella magnolia near the northwest balcony had to be removed this year. Hydrangeas are most appreciative of the cool weather and are doing splendidly this year. One of my favorites here is the Japanese Schichidanka hydrangea. In the very old big blue pot is Madame Mouillère, a French “hortense” hydrangea that is a newer and better form of the Soeur Thérèse that is the classic white in France. (I’ve had Soeur Thérèse here a couple of times but I think it doesn’t like the heat; temps are generally cooler where it flourishes in France.) Wilkerson Mill Gardens just south of Atlanta is an excellent source of exceptional hydrangeas; Beaver Creek Nursery also has many good ones. The pretty-but-past-their-prime light blue blooms in the bog garden fountain near the reflecting pool are camassia bulbs backed by native yellowroot, acorus and carex. The pretty little shrub near the stairs with the golden leaves is Spiraea thunbergii ‘Ogon’.

I particularly like the mixed shrub and tree plantings on the property’s borders because they really bring in the wildlife. Below the tall hardwood trees, there are several varieties of aesculus, calycanthus, hamamelis, chamaecyparis, cornus, cryptomeria, corylopsis, magnolias, illicium, osmanthus, vitex and viburnum, among others. It is an incalculable pleasure to be outside working in the garden and seeing raptors, birds and butterflies move through the middle layer of the garden.

Maintenance – We do a weed eating of specific areas a couple of times a year but otherwise I mainly pull weeds as I can get to them, especially after good rains when the roots will come with the plant. I often find the stones we’re looking for when I weed. The “landscape” here can get by on its own. It did so for many years when we first came to live here when we were both working long hours. Once we did work on the exterior, we mainly concentrated on constructing safer ways to sit and walk on the slopes and that work has been worth every ounce of its investment. In recent years, I have added plantings for either privacy and screening on the boundary lines of our property or for viewing from inside the house. There is a lot more that could be done with the trees here and I keep a list of priorities for when I can afford that work—I recommend Cortese Tree Specialists for their skill and care. A couple need to be dropped and they are marked—one is an ash and the other is a young maple too near the power service line. Several need lower limbs cut—“limbed up” to allow a bit more sunlight onto lower-story trees and shrubs. One large maple may eventually better serve as a standing snag—similar to the large ash further down the slope that managed that conversion all on its own to the delight of many birds and squirrels—in order to avoid dropping its larger dead limbs on plantings beneath it.

Watering – No irrigation and very little landscape watering except for the driveway rhodos, which otherwise look like a tribe of pathetic elder statesmen during drought. I have main hose lines with full KUB source pressure to make it up the slope from Carriage that then have smaller lines branching off of them. I pretty much only water new plantings and containers and for them I haul a lot of water from the frog/reflecting pond in a 2-liter can—it seems to give them a better start and, of course, is free of chlorine.

Fertilizing – My old horse, Bilbo Baggins, is everywhere in this garden because its fertility is largely a product of manure from him during the last 12 years of his life on the horse farm where we previously lived. (The new gentleman farm owners asked that we let him stay in the pastures he was accustomed to—and Kenneth’s vast collections also to reside in the barns—while we took care of Bilbo every day and transported his manure at intervals to Blue Note until he died at age 36. It puts a lot of problems in perspective to start and end every day by shoveling horse manure into sheetrock buckets! I actually miss him and the act of taking care of him very much, but then I remember he truly is in the excellent—if scant—soil in our garden.) Leaf mold and mulch is a big part of the ecology of our woodland garden. I would prefer to vacuum and shred leaves but I have not found any way to do that in a reasonable or economical way. I remove some build-up of leaves but, for the most part, the wind distributes as it will and we just try to keep the driveway and paths periodically raked. Very occasionally I need to rescue something from under a pile but for the most part the plants seem to do fine.

Finally, if you would like to read more on the subject of the American woodland garden, there is no finer classic source than Frederick Law Olmsted. For the present day, the best author is Rick Darke.

This entry was posted in Gardening and Wildlife at Blue Note Garden on May 20, 2016. It is based upon a talk given to several local garden clubs by Theresa in 2016-2017.