blackberries Blackberry Bane

The hillside that we’d had denuded of blackberry vines last summer was needing something. It is a steep slope, about 45 degrees, so we want it to be held firm with deep-rooting plants. The steep hillsides around here have never been managed with erosion control in mind, mostly being allowed to populate with blackberries. Blackberries are a noxious weed in our region, and are not a good erosion control plant. Though they have aggressive and spreading root systems, their root type is thick and tuberous, a little like a potato. The roots don’t spread very deep or wide in a “net” fashion like you’d want for holding soil.  And though blackberry vines grow tall, their understory lacks leaves, so they don’t provide a lot of leaf surface for capturing and absorbing rainfall.

The Quiet Movement of Soil

Soil erosion is an under-served subject, most people don’t think much about it since it usually happens so slowly it’s not noticeable. There are some interesting clues that soil movement has been taking place on our property, however. Take a look at the alder trees which are at the bottom of one of our slopes. TreesThey are sitting on a gentle incline that leads to a steeper slope.  You can see that over time, they have been sliding downhill. The uphill-side of their root systems has been gradually uncovered and exposed. So gradually that the trees have just adjusted by growing bark there. And their trunks are bent, where they keep having to curve to correct their path and grow upwards. So, though we’ve not had any major mudslides or acute hillside loss, we are experiencing very slow hillside loss every day. And that needs to be stopped. So, we’re working hard to remove the blackberries everywhere, and replace them with better slope-holding candidates. 

Grass as First-Tier Defense

Grass is one good one, especially deep-rooting varieties designed for this purpose. When our hillside was graded last summer, we immediately put down about 200 pounds of grass seed. And we covered it with loose straw, which is one of the recommended ways to discourage soil slides while your plantings are taking hold. As the straw decomposes, it also provides moisture-holding properties, and finally fertilizer for whatever you’ve planted there.

GrassBut, our efforts were thwarted some. The chickens took great delight in scratching through all that straw to eat the grass seed. :-{ This caused much of the straw to slide down the hill over time, defeating its purpose. And the soil there is sandy and low-nutrient, so the grass plants that did manage to germinate look somewhat anemic. And besides, we don’t want to have to mow that hillside; it’s too steep to comfortably walk on it while swinging a string trimmer. We could flash-graze it eventually, but it may be a while before we have that area fenced. We’d like to populate it with bushier plants that will fill it in over time, make it maintenance-free and also attractive.

Trees, Shrubs and Ground Cover

plantingEach year, our local NRCS branch, the Snohomish Conservation District, holds a plant sale. They provide small and inexpensive plant starts intended for mass-planting and restoration projects. Most of what they sell are native plants, and native is good, it means the plants will need less “help” to thrive in our climate and soils. The plant sale also specializes in erosion control plant species. I ordered 135 plants from them this year just for this hillside. I chose plants that are good for erosion control, don’t mind dry/sandy soils, and don’t mind shade, as this area will be very shaded once we build a barn next to it. I tried to avoid plants that are blatantly toxic to livestock. And, I chose smaller species- we don’t need any 100-foot-tall pines falling down on the barn during a windstorm! The Washington Native Plant Society has great information on choosing native plants for certain landscaping goals.

The varieties I chose were:

Top story: Vine Maple, Oceanspray, Cascara, Serviceberry

Middle story: Mock Orange, Nootka Rose, Red Flowing Currant, Indian Plum

Understory: Salal, Coastal Strawberry, Kinnikinnick

Order

Above is what our order looked like: it never seems like much because the cultivars are pretty small. But this is nice, it makes them easier to plant! And it’s what makes it affordable to buy over one hundred plants in a sitting. This order cost $227, averaging about $1.68 per plant.

It took us a couple of hours to get them in the ground on Saturday. We tied fluorescent ribbons to them so that we can spot them and monitor them as they grow. I was a little disappointed that some of the plants weren’t packaged as well as they could have been, and their roots were getting dried out, even though I’d just picked them up the day before. This comes with the territory, as much of the sale is staffed by volunteers, so packaging quality can be hit-and-miss. We doused all the plants in a bucket of water and root-pruned them before planting, and thankfully it rained the next day. So hopefully we’ll have a decent survival rate. As we see how the different species perform there, we can buy more of the most successful ones in next year’s sale if need be.

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