Native Planting Design for Erosion Control

By Guest Blogger Troy McGregor

Troy McGregor, owner and operator of Garden Natives nursery, contributes practical and knowledgeable information on successfully incorporation California natives into your garden.  Today's post is on erosion control for sunny slopes.

 Heavy soils and slopes aren’t the terrible twins that most homeowners think. With slope comes drainage and with drainage comes more native plant choices. Stabilizing a slope makes a lot of sense and requires more than jute netting and crossed fingers. Get it wrong in a really wet year and you risk damage to not only your property but those of your neighbors.

Enough of the ‘Doom and Gloom’ – lets talk about solutions. Our native plants are slope specialists that have been holding California together for quite a while now. Using a combination of trees, shrubs and perennials not only holds the soil in place, but reduces the impact of rain and slows run off. Living on the ‘Hot’ side of the hills is often a challenge for the traditional natives. The soils are different, the weather is warmer and the fog just doesn’t have the legs to climb past Tilden. Don’t be discouraged though as many other natives are more than happy to move in.

Today’s example is a  front yard with mild slopes that require vegetation. One is in baking sun all day and the other has sun till about 2pm. Irrigation is via drip (in-line ½” with emitters spaced at 18” – not single emitters) and is used during the warmer months every 30 – 60 days.

Here is a combination that will work in most situations. Manzanita, White Sage, Deer Grass and Californian Fuchsia.

Arctostaphylos densiflora ‘Howard McMinn’ (Manzanita) is a bullet proof manzanita that earned its place in the landscape years ago. Its design height is around the 6’ mark but it is capable of growing larger. For larger manzanitas try Arctostaphylos bakeri ‘Louis Edmunds’ (8-10’) or Arctostaphylos manzanita Dr. Hurd (10’ +). I like to prune manzanita up to expose that incredible bark and the twisted form of the trunk.

Arctostaphylos edmundsii ‘Carmel Sur’ (Manzanita) is a well behaved and polished looking ground cover. When fully grown it can cover an area 6’ wide which is perfect for both reducing runoff and slowing the speed with which rain contacts the soil.

Salvia apiana (White Sage) is a plant you don’t see to often which is a shame. It may lack the showy flowers of its cousins but it more than makes up for it in form and foliage. This is a classic contrast plant and one I try to use a much as possible. In an ordinary flat yard, our wet winters and heavy soils would see white sage pack its bags and head back down south. Fortunately for us and the salvia we have a slope which means drainage. The suitcases are back in the cupboard and its margaritas all around. We have a happy plant. Expect white sage to grow between 2-3’ high and 3’+ wide. Flowering stalks will emerge in the spring adding another 3-4’.

Muhlenbergia rigens (Deer Grass) is an adaptable and striking grass that is showing up in more and more landscapes. This is a big bunch grass with a big root system that is ideal for our slope. In the central valley it can reach 6’ high (incl. flower stems) with a girth to 6’. In our area it is uncommon (but not impossible) and more likely to be 4-5’ high and wide. This warm season grass contrasts well with both the small leaves and bark of the Manzanita and the foliage of the Salvia.

Epilobium ‘Catalina’ is one of the larger Californian fuchsias having a design height of 3-4’. New growth begins when the weather starts to warm up in the spring with the flowers following in late summer through to fall. ‘Catalina’ is a flower mass producer which will have the hummingbirds flocking to the yard. These plants have a bit of a habit of spreading themselves around by either seed or rhizomes, which is only a problem in a highly manicured garden. Prune plants back to a few inches from the ground when new growth begins in the spring for a fresher appearance.

                 

Try adding some annuals and bulbs such as Mentzelia lindleyi (Blazing Star) and Dichelostemma ida-maia (Firecracker flower) for early season color until the fuchsias get going.

Comments

[Susan]

Hey Troy!
I like the annuals idea - any suggestions on how to adjust the irrigation to accomodate?

[Troy]

Great Question. As a general rule you shouldn't need to adjust your irrigation at all.

For example: In a perfect situation you would have purchased fresh seed in late summer or early fall and scattered it in a pre prepared location just as the rains start. The rains and cool weather would initiate germination and continue into the spring promoting solid growth of new plants. Being water watchers we would have turned our irrigation system of during all of this rain and not turned it on until the soil started to dry in spring or later.

In years such as the last one where rains were not sufficient enough to keep the soil moist enough for germination, a little assistance from the irrigation system would be helpful.

Additional irrigation once the rains have ceased may prolong the blooms of some species but it is best to replicate their natural cycle, ensuring repeat visits in following years.