Do you have a slope on your property down which excess water flows, causing erosion on the slope and/or a landscape drainage problem below? Homeowners can address this problem by building dry creek beds. Besides the practical aspect of improving landscape drainage, these features can also be attractive. In fact, some folks with absolutely no drainage problems in the yard build them just because they like the way they look.
Instructions for Constructing Dry Creeks
- First, plan the course that the dry creek bed will take down the slope. Mark the two edges of that course with landscaper's paint. A curving course that winds its way down the hill looks more natural than a straight course. How high up the slope should you start? In some cases, there's little choice. For instance, if a landscape drainage pipe that's already in place is dumping all of that excess water onto your property, your decision is clear-cut: Begin the project by grading the land right under that pipe.
- But in cases where you have more leeway (especially for features that will be purely decorative), attempt to disguise the "headwaters" of the dry creek bed by making it bend out from behind a large boulder or some plant material. When the source of a stream is mysterious, viewers have to use their imagination. And what viewers construct in their minds can greatly enhance what they merely see with their eyes.
- We've talked about how high up the slope to start. But what about where to finish down below? Some homeowners redirect excess water toward the street. But it's best to think about a worst-case scenario when dealing with public property, because that means dealing with the government. And the government can be a real stickler when it comes to issues like redirecting excess water. So check with your local public works department first. If their response is positive, get something in writing that says so.
- What if you're not allowed to redirect the water to the street? Unless you already have a landscape drainage system in place (allowing you to route the runoff into that system), you have two main options. You could channel the water to a location on your land (but make sure it's truly your land, not a neighbor's) where it's less troublesome and where, if the soil is sandy enough, it can percolate harmlessly down into the ground. A second option is to build a pond and funnel the water into it.
- So much for the start and finish of the course. What about its depth and width? These dimensions don't have to conform to any exact rule. After all, look at dry creek beds in nature: They are not all of the same depth and width. But there's a general rule you can follow: Dry creek beds tend to be wider than they are deep, which is good news for you, because it means less digging. A 2:1 ratio is about right, meaning you could make your feature 3 feet wide x 1.5 feet deep, for example.
- With the planning done, now it's time for the first real work in the project: the digging. It's easy to build dry creek beds, provided that the soil you'll be digging through isn't strewn with roots and rocks. Those with difficult soil to work with can take solace in the fact that the digging will be the toughest part of the project. The rest is easy.
- Take the soil that you're excavating and mound it up along the sides of your dry creek bed, as you go. This will reduce the amount of digging that you have to do, since you'll be lowering the base and raising the sides in one motion. Tamp down this excavated soil with a tamping tool.
- After the trench for the dry creek bed has been dug, lay down landscape fabric along its whole length. You want the fabric to cover the mounds of earth on both sides, as well as the trench. Hold the fabric in place using fabric pins or garden staples. Now for the part of the project that will be visible to viewer's: the rock.
For projects intended to improve landscape drainage on very steep hills, some folks mortar the rocks into place to form a solid channel that will carry water away. Unless you find that it is a necessity to take this measure, however, it may be best to avoid it. Mortared structures in contact with the ground are susceptible to frost heaves in cold climates. But if you do go this route, to guard against frost heaves, you can dig your trench deeper and apply a few inches of crushed stone before laying down your landscape fabric. The good news is that the use of mortar is usually unnecessary for dry creek beds located on all but the most severe slopes. If you're afraid of having your stone wash away, use lots of large stone to anchor the project.
If you do use mortar, apply it only to short sections of the fabric at a time, since mortar dries quickly. Use at least 2 inches of mortar. Lay the rocks in the mortar, then repeat the process with the next short section. It's easier to work from the top of the slope, down.
- You can use rock of various shapes and sizes, but many homeowners prefer to select more round rocks ("river rocks") than flat ones. Round rocks conjure up an image of the water that has been gushing over them, knocking them about and causing them to become round over time.
- Place small river rocks in the center of the trench; the water (if any) will flow over these.
- Place your larger rocks on the sides of your feature, where they'll help channel the water and where they'll have the most visual impact. Save any boulders for the biggest bends in your stream's course and to disguise the "headwaters" of the dry creek bed (as discussed in step #2 above).
Planting Ideas, Tips
- After you build dry creek beds, you can dress up their sides a bit. As always with hardscape features, you can make them look better with plants, because the plants will soften the hard look of the hardscape. Adding a planting to your dry creek bed will further aid in preventing erosion, as well, because the plant roots will hold back soil.
- Unless you will be digging through very fertile soil, you will probably have to improve the ground for planting by adding soil amendments to it.
- If you're ambitious, you can go beyond a simple planting and install a landscape bridge over the feature and plant tall ornamental grasses to serve as "bookends" at both entrances to the landscape bridge. Adorn the landscape bridge with hanging container gardens to create a knockout focal point for your yard.
- Plant selection depends on the same factors that you would consider for any other planting, with practical factors taking priority. If your dry creek bed is a big one, there may be multiple sets of growing conditions to address. For example, if part of it is going to be really wet at times, grow plants that do well in wet areas there. Grow full-sun plants in a spot that receives sunlight all day long, but shade plants in a spot shaded by a large tree. By the way, that large tree will also increase your maintenance, as any debris that falls from it (branches, leaves, etc.) should be removed.
- Once you have taken into account the practical factors, you can move on to deciding which plants would look best in the planting. Many gardeners like the look of the branches of a small weeping tree hanging over a stream bed (dry or otherwise), with Crimson Queen Japanese maple (Acer palmatum dissectum 'Crimson Queen') being an especially popular choice. But when using such trees and shrubs, mix in some suitable shorter ground covers, as well. A planting will look more natural if plants of different heights are combined, rather than going with plants that are all of the same size.
- Complete the project by adding mulch around the dry-creek-bed plants, to keep down weeds. A variety of different materials can serve as mulch, but, for obvious reasons, stone mulch is a strong choice here.
- Landscaper's paint
- Landscape fabric
- Fabric pins or garden staples
- River rocks and boulders
- Mortar and a wheelbarrow for mixing the mortar (in projects where mortar is called for)
- Tamping tool