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Ravine-Bird's Eye View
above: A drone's view of our ravine in mid-fall 2018. Much is under construction in this photo, but it's clear where paths have been built. There are boards waiting to be cut and placed for a puncheon near the center and the round circle is approximately where the natural spring is located. We will be directing water from the spring into a pool and then out of the pool to continue on the way it normally runs.

THE RAVINE PROJECT

WHERE WE STARTED

It never occurred to me that our ravine would take on the significance of Sisyphus when I began the project. It was triggered initially by the unfortunate death of our cat, Tashi, on Thanksgiving, 2015. At that time, the blackberry in the ravine had gone completely amuck and was shooting over a 12’ tall Camellia and eyeing our house as its next obstacle. It made a great hiding place for a coyote.

My reaction to the death of our cat was obviously one of immense sadness, but I was also furious with myself that we had too long ignored the rambunctiousness of the thugs in our ravine-flora and fauna. I spent the remainder of that weekend attacking ivy and blackberry at the upper edge of the ravine. Indeed, until spring came and I had to address our upper garden’s needs, I was a weed-pulling maniac.

plan
PLAN VIEW

 

 

 

Ravine before
Looking west along the south slope just after the cherry trees were removed in January 2017 & we began removing ivy here.

WHERE WE'RE GOING

I returned to the ravine the following fall, to plant some natives and various ferns and continue clearing ivy, blackberry, and also drifts of stinging nettles. Here I was in the midst of a wild space trying to eliminate invasive species or plants a little too well established for a garden that had grown there for many years (including the 25 years we had lived there). A nearly overwhelming task, except I looked at it ‘one bite at a time’. As I pulled, a path evolved. We had always wanted a path to our creek (at the far end of our ravine and at the bottom of very steep slopes). I began to fantasize many paths and where they might lead and I also began to consider the design of a wild, native space. Now ‘design’ and ‘wild’ could easily be mutually exclusive. However, guidelines help a gardener create not only a cohesive space, but one that will maintain the nature that the gardener perceives or conceives.

Our ravine is a woodland area primarily, with the exception of a hot, sunny slope that faces southwest. At the bottom of that slope there is a natural spring and wetland. There are four steep sides, so it’s a large, bowl-shaped, sunken garden. Getting in and out of it was going to be difficult and would involve terracing and many steps to reach the spring, which is roughly thirty feet from the top to the bottom. The diversity of biomes, in this roughly half acre, is extensive.

Ravine biomes
A view of the most diverse north slope of our ravine with biomes circled and labeled.

GOAL SETTING

I realized that, with so much plant potential, a theme for the garden would assure a cohesive design. Plant lust could easily cause the design to go sideways, so I wrote a list of goals to guide my editing.

  • Include as many native plants as possible, preferably at least 30%. This includes nativars. Also include ornamental exotic plants but they have to act like natives (i.e. using the water on site once established) and suit a woodland garden. (Banana and palm trees would be out of character.)
    Clarkia
    White flowers of native Clarkia and Holodiscus fill this photo while globes of spent Alliums add some form to the mix

  • Limit flower colors to white, pale lavender, and soft yellow so they can be seen from a distance (our living room window specifically).
    Ravine Polygonatum
    Polygonatum x hybridum 'Striatum' (native cultivar) Isn't deer resistant, so I have to spray on occasion, but it's so beautiful it's worth the effort.

  • Select deer resistant plants. Bunny resistance is a plus. God help us if beavers show up!Viola
    Viola and Romanzoffia californica have so far proven deer resistant and are terrific at covering ground and even reseeding!
  • Much of the area is shady within that wide range of biomes, so I want to include a fernery and learn more about ferns, in general. Tellima_Polystichum
    Native Tellima grandiflora and Polystichum polyblepharum (tassel fern).
  • Keep native plants in place and work around them as much as possible, moving them only as a last resort. Big leaf maple and elderberry seedlings and a few other high-spirited natives are exceptions to this rule.
    Angelica
    Angelica arguta in our spring - it's a nice stand of it and I have no intention of moving it.
  • Use materials that keep the garden and its paths natural in appearance.cedar chips
    Cedar chips not only look natural, they are lightweight and therefore easier to maneuver than stone up and down steep slopes. Naturalistic art emphasizes this is a natural garden.
  • Develop an inexpensive, naturalistic way to retain and stabilize soil, create terracing, and carve paths. Use as little outside help as possible, with the exception of my spouse and occasional friendly volunteers.Fascine
    A typical fascine construction using two tree stakes and found branches on our property. Pinus 'Chief Joseph' is newly planted waiting for some more plants to surround it.

  • Watch what Nature does.oyster mushrooms Oyster mushrooms helping to decay a fallen alder log.

Over time these goals might change, but it's a great method to keep you mind focused when you visit a nursery and your eyes begin to glaze over and your brain gets a little fuzzy.

IMPLEMENTATION STRATEGY

Having a list of goals is a great start, but it’s also important to develop implementation strategies. After the first year, we had to remove 3 mature cherry trees (due to aging issues- they are not long-lived trees on the west side of the Cascades) that I had planted 26 years prior, as well as one of the medium size big-leaf maples. (There is an abundance of the latter, as well as an insane number of seedlings.) I had the tree company cut everything to a specific size that I could easily use in creating steps to improve access to the bottom of our ravine.

A few months after that we vacationed in Rome where I discovered an ancient Roman method to retain soil. I was delighted that our debris piles of logs and branches could be assembled into something called 'fascine'. Soon after I saw elegantly-fashioned bamboo fascine at the newly installed portion of the Portland Japanese Garden. I knew that I had discovered an inexpensive technique to retain and stabilize soil and could make it look good. Win-win, I said to myself and set about to make my implementation list:

STRATEGIES LIST
  1. Evaluate whether any large plant currently on the site needs to be removed, particularly larger trees. Have tree health appraised and if any are unhealthy, remove them before beginning anything else.

  2. Exercise caution about how much existing material should be removed at any one time. Limit it to what can be planted right away to maintain slope stability.

  3. Stabilize soil with constructed fascine. Set two verticals plumb into a slope at a distance that is practical. I use 2” x 6’ tree stakes which I set roughly six feet apart. Pile up collected branches behind those up to a height where, if soil were to pile up against it, the height would be where the soil’s angle of repose causes it to stay in place. Pound or trim the posts to just above that height. Fascine is designed to eventually decompose, so a planting strategy has to be part of this approach. (If you have extreme situations, i.e. visible soil cracking, you should always consult with a geotechnical engineer for additional advice.)

  4. Plant intensively (closer together than normal) with smaller plants to limit slope disruption and with plants that have fibrous roots (like ferns, grasses, and sedges), rhizomatous roots that will help knit soil together (like salal and inside-out flower), and trees and shrubs that will grow larger soil-stabilizing roots.

  5. Create access into the ravine by terracing slopes and establishing paths for garden maintenance. This involves cutting into some areas and filling (and compacting) others, respecting the existing slope as much as possible.

  6. Define your best approach to hold soil. We are using fascine to hold the upper side of the path and on the other side of the path use 2-3’ long rebar as the verticals, depending on the degree of slope and lay burlap ‘logs’ against them to retain soil. (Burlap logs: Bundle lengths of smaller branches in burlap and tie the ends with twine.) Dig soil for paths when soil is dry to moist, but not wet. It’s more stable then. When it’s wet, it’s extremely slippery and very dangerous.

  7. Always water new plants until they are established - yes - even 'drought-tolerant' plants. Some will take longer than others. Place plants in locations that match their native habitat as closely as possible for the best success. Be cautious about overwatering on a slope. You don't want to wash your soil away!

  8. Limit how much material has to be removed, Weeds are obvious, but birds love areas of twig piles, so keep as much of those in place as possible. Consider using them in an artful way, a la Andy Goldsworthy.

  9. Use materials on site or lightweight materials to make it easier to get them into place. We decided to use cedar chips initially because they have sharp edges that help them dig into the soil, are fairly easy to move into place, and don’t decay rapidly. Once everything is stabilized and we need to add new material, we’ll use trail mix (a shredded bark mix) over landscape fabric.

  10. Watch Nature, paying close attention as you remove weeds. We’ve discovered some precious and unusual native plants and - salamanders!. Our huge alder log, that divides the ravine in half between our road and our house, is an amazing host of fungi – including edible oyster mushrooms. It also has native, summer-dormant licorice ferns. (Incidentally, we discovered morel mushrooms at the top of our ravine this spring.)

salamander


  1. Pace yourself. Balance your enthusiasm with a dose of caution, especially on slopes that can mean some physical soreness beyond which you’re comfortable. I work there all year, bundling up for cold weather, and usually work a few hours at a time. In good weather, I work until I’m tired varying the type of work I do to exercise different muscle groups. It’s easier to work longer in cool weather.

  2. Talk to as many gardeners and experts about native plants as you can. Study them online and through books that have a good array of possibilities and information. I belong to several native plant Facebook groups, too, which provide a surprising amount of information. You’ll be surprised at how many natives are very garden-worthy plants.

  3. Keep your eyes peeled for resident critters, learning what their tracks look like, in some cases. Spray plants for deer & rabbits as needed with an organic spray, especially newly installed plants. We are already organic gardeners, but this area will need to be especially so, given its close proximity to Salmon Creek. Watch for deer damage to native plants. Only spray if it’s really necessary, otherwise let nature take its course.

WORK IN PROGRESS

Today, 3 years later at the beginning of 2019, we are about 1/2 around the ravine. This year many new plants will be added, as we contine to remove the weedy thugs, stabilize the steep slopes, and add plants that might have been here naturally or naturally work with native plants. During the summer, when the wetland has dried out a little, I'll tackle taming the spring. Stay tuned for some before and after photos.

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REVISED: 14MAR2019