June 2002 Colorado Green Article
Is there such a thing as “no-maintenance” gardening? Of course the answer is no but there are techniques one can use to minimize maintenance in the garden whether it is a small residential garden or a large commercial or public landscape project.
As a landscape architect, I don’t believe any of our clients have ever asked us for a high maintenance design though some are more interested in maintaining or hiring someone else to maintain their gardens than others. Everyone has busy lives where less work in one area, such as gardening, leaves room for activities in another arena.
When we first analyze a client’s landscape we look at all aspects of the space in relationship to the client’s needs and desires. Curiously enough the basic Xeriscape/ water conserving principles, now of greater importance than ever, are ones that apply to low maintenance design as well.
Let’s look at the things that are most often a maintenance concern in the landscape.
- Lawn and Hardscape
- Plant Control-edging, mulch, pruning
- Plant selection and health
- Grading & drainage
Lawn and Hardscape
One of the most frequently noted maintenance problems is “funny” pieces of lawn that serve no real purpose but need to be watered, fertilized and mowed. Our main object in designing a lawn area is to create a smooth flowing, usable area of lawn that is contained and separated from other planting areas by a mowing strip, if affordable, or at the very least good quality steel edging. Eliminating unnecessary lawn areas also saves water since lawns require more water than any other type of planting. Separating the other plants from the lawn makes it easier to water according to the needs of the different types of plants. Occasionally clients wish to create paths of lawn. In our climate this style of path is only practical where one doesn’t need much or any supplemental water and even then one has to mow, fertilize and trim the path. Either the path gets under watered or the surrounding planting beds get over watered, both clearly undesirable in a drought situation.
Reducing the size of a lawn to a useable size and shape allows one to have beds of plants and larger hardscape areas which also reduces water use. Most of our clients have a need for a larger patio or deck space than they originally imagined. Once one is outside, the scale of space is very different. A six-foot tree that would look large inside is dwarfed outside. The same is true of hardscaped areas. Furniture arranged on a patio tends to make the space seem much smaller. Most hardscape is lower maintenance than planted areas. The question becomes one of materials and installation techniques. Well-installed concrete is very low maintenance. Sweeping and occasional snow shoveling are usually all that is required for years. Concrete tends to crack so it needs to be designed to crack at proper intervals using expansion and contraction joints. Many people find plain concrete to be unattractive and the industry has developed many techniques over the years to enhance and change the look of concrete. If a client wants stone or brick this can be added in bands or other designs in the concrete or laid directly on top. Properly laid these additions should not add significantly to the maintenance of the surface. Some pointing of joints and the like may be needed after several years of our variable weather conditions.
Another type of flat hardscape is brick, stone or concrete pavers laid dry on a sand bed. This is a less expensive method of hardscaping and has a number of other advantages. It can be laid over tree roots and still allow water and air to get to the roots. It can be laid with ground cover growing between it such as pussy toes, wooly thyme or mat-type veronicas. It is flexible and can be added to or subtracted from as needs and desires change. It requires little to no watering. The disadvantages include occasional weed growth in the cracks, possible settling and/or heaving of the paving and some periodic need to water the ground covers. It can also be difficult to shovel and keep clean.
The use of ceramic tile tends to be problematic in our freeze/thaw climate but concrete or some kinds of stone tiles can be used. Walks are also made out of these materials.
It was once be true that wood decking was less expensive than concrete and the fact that a relatively handy homeowner could install a deck himself, or afford to hire someone to install it, has lead to a number of wooden structures in the landscape. Sometimes wood decks are the only solution to a difficult problem. In those cases I recommend using deck materials that are of the highest quality. Con-heart redwood is one of the best. While most recycled plastic wood substitutes remain unattractive, in my view, there are a couple of decent looking recycled plastic/wood products on the market that work well in the right situation. Installed in the mountains, where it is usually cooler, or in shadier city situations seem to work best for these products as high heat can cause them to sag and warp. Be aware that the sub-structure of decks and the like still has to be made of structural grade wood and the spacing of joists must be closer when using these products. Over the years we have designed decks for clients who have later traded them in for lower maintenance materials such as those mentioned previously. I still think a good quality deck is beautiful and we continue to design them but, over time, they require more maintenance than other materials.
One method of keeping plants under control is the use of edging. We recommend 1/8” x 6” hot rolled steel, welded or overlapped and bolted together at the joints, not the other flimsier varieties often seen in the landscape. The 1/8-inch dimension in combination with the “hot rolled” is important because the top edge is not sharp like other edges. The 6” dimension is important to keep the grass roots from creeping under the edging into the neighboring beds. This sturdy steel edging is much easier to install in a smooth continuous line without kinking or bending. Used in combination with brick, stone or concrete pavers (on the bed side of the edging) it makes a very nice mowing strip. A more expensive and permanent edging can be installed using concrete by itself or with stone or brick laid on top. The disadvantage of this method is the lack of flexibility in changing a bed edge. Eight inch or wider mowing strips are also useful at the base of walls, decks and other landscape features where lawn trimming is a problem. All edging should be installed so that it’s invisible except upon close inspection. Mower blades should be able to run over the edging or mowing strip without hitting it. We recommend the top of steel edging be at the top of the root zone of the lawn, not at the top of the blades of grass.
Mulching beds after planting is also one of the best ways to reduce weeds and conserve moisture. We do not recommend weed barrier fabric except under rock products or in cases where existing weeds are so bad (particularly bind weed, thistles and bluebells) that they warrant the use of the fabric. Most projects using weed barrier fabric look terrible after a short time. The mulch slides or blows off the fabric causing unsightly patches of fabric to show. In addition, the fabric really doesn’t prevent weeds from coming up unless it is installed where no plants are intended to grow. Where plants are planted through the fabric the weeds just have to spend time migrating over to the hole that was cut and then twine themselves in the new plants often causing worse problems. Birds and wind tend to scatter weed seeds that may take root on top of the fabric. Mulch tends to stay in place much better if placed directly on the ground. It has the added benefit of adding humus matter to the soil over time as it disintegrates. In general we find weed barrier fabric to be a nuisance at best and a big maintenance problem at worst. Unfortunately, many contractors and others in the green industry tend to use weed barrier fabric everywhere. Many municipalities require the use of weed barrier fabric on their projects and no doubt many of the design professionals also think it is the thing to do. It may be, like the use of black plastic in past years, eventually found to be undesirable except in proper situations as described above.
Plant selection, placement, health, and pruning
Good soil preparation is the foundation for healthy plant growth. Healthy plants need less attention (translate that to maintenance) than unhealthy ones. Good soil preparation often eliminates the need for fertilizers. Adding organic matter to the soil conserves water by holding water in the root zone. Leaving clippings on the lawn (lawn mulching) also eliminates the need for added nitrogen on the lawn. We recommend 4 yards of good quality compost per1000 square feet, thoroughly tilled into the soil to a depth of at least 6,” for all planting areas including lawn areas.
Since trees, shrubs, perennials and ground covers require less water than lawn, we recommend that they be located in beds separate from the lawn where they can be watered separately. When these plants are located in the lawn they often cause maintenance problems. The grass grows in and around them making the plants look terrible and the grass impossible to trim. Trees, planted in the lawn, are subject to injury by lawn mowers and trimmers. Their roots sometimes rise up in the lawn as well. Placing these plants in their own planting bed (with properly installed edging) eliminates these problems.
Pruning is another big maintenance concern. In general plants should be allowed to grow according to their natural habits. If the desire is to have a sheared plant, such as a juniper, one should start when the plant is young. Do not begin in ‘middle age’ when the plant is overgrown and, after being sheared, ends up being brown and bald. Topping shrubs and trees is always a poor solution producing ‘witches-broom’ type growth that requires constant attention. Care should be taken to selectively prune shrubs, when needed, according to standard industry pruning practices. Except for problems caused by storm damage, disease and the like, most pruning can be avoided by using plants specifically selected for the space available. Landscape architects and designers have a kind of “Catch 22” approach to this problem. If one selects and places plants according to their mature growth pattern, and this often varies depending on soil preparation and watering practices, the resultant new landscape would look very bare. Most landscape architects try to space shrubs in a kind of middle ground so that they look pretty good within a five-year period. If a shrub is listed as having a mature height and spread of 5-6’ we usually space them four feet apart knowing that the plant will start out way smaller, will look reasonably good in about 5 years and have some room to grow to maturity. Eventually these plants will grow together. If a client is willing to wait 10 or more years for a really good look we can space them at their more mature distance. Ground covers and perennials tend to spread faster and are placed close to their mature spacing when installed. Deciduous trees, which are slower to mature, are never the less permanent fixtures in the landscape and need the proper spacing for ultimate growth. On occasion we will place trees closer together to achieve a special effect but we try to give the big canopy trees their proper distance. Providing evergreens in the landscape that fit the space available has been difficult. Many of the available evergreen trees get very large. Everyone in the trade has experienced the site where that “cute little spruce” grew into an enormous space taker, over-shadowing many a building and grounds. Denver has taken to prohibiting standard Colorado Spruce in many of its projects because they grow so large. Spruce and firs also like water, though, like most trees, they can take less as they become well established. Pines, once established, require good drainage and much less water. The local nurseries have relatively recently begun marketing dwarfed and upright growing varieties of the larger evergreen trees allowing a wider choice for designers. Previously, upright junipers, bristlecone and pinon pine were the only reliable ‘small’ choices and each has its problems. One of our landscape contractors maintains that all the newly marketed smaller evergreen choices will eventually get large. He says they just grow more slowly. I hope he’s wrong as these evergreens offer opportunities previously unavailable. If they live up to their reputations, these evergreens will prevent the need for much pruning and removal of overgrown and half dead trees.
At this point it is probably good to mention the need to pay attention to the location of overhead power lines when placing evergreen and deciduous trees. The Public Service Company (Xcel Energy) can issue guidelines but the main thing is to make sure that only smaller maturing trees, less than 30’ mature height, be placed near power lines. The city is full of trees that are in violation of this guideline and periodically the Public Service Company sends a crew out to prune the trees that get in the way of the lines. The results are usually unattractive and may jeopardize tree health by weakening its structure. Spruce seem to be particularly vulnerable. If they become one-sided from a heavy pruning of their branches they may blow over in a big windstorm. Because of the danger, most tree services will not prune trees near or in contact with the power lines so one is at the mercy of the crews sent by the power company.
Trees can cause problems with paving. Some tree roots tend to rise up as they grow and can cause heaving of paving leaving an uneven surface that is less than perfectly attractive. In a perfect world trees would be placed away from paved surfaces so the heaving problems wouldn’t occur. However, most people like trees to shade paved areas and placing trees near a paved surface and/or a house is generally considered desirable. The shade from trees not only cools but also reduces water evaporation. .If there is a big root problem existing or anticipated one can try some of the root barrier products currently on the market.
Grading and drainage
Steep slopes and drainage are two additional problems that lead to maintenance difficulties. It seems that many of the new developments are building houses on small lots with extremely steep slopes. We have been called to many locations where slopes are steep, the client has been told that if they mess with the grading their warranty is void, and they are unable to walk around the house because the slope is so steep, much less grow things. Many projects offer walkout basements which create additional grading and drainage problems. No doubt the developer has brought in fill dirt and even if he tamped the soil properly, the soil is bound to settle. The developer has provided steep slopes in order to avoid water in the basement or cracking foundations. It seems to me there is some middle ground between the overly steep slopes often provided and no slope at all. Some soils engineers believe that adding organic matter to the soil and keeping the soil at a consistent moisture level is more important in combating shrink-swell soils than keeping water away from the foundations. They don’t want the soil to dry out completely or get too wet. Obviously maintaining drainage away from the house and other buildings is very important. It is a problem that affects both new and existing landscapes. Sometimes raising window wells, waterproofing walls and raising the soil level around foundations is necessary to create positive drainage away from the house and prevent flooding of basements as a result of heavy rains and over-watering.
Well-designed and constructed retaining walls and steps may solve a number of problems and add greatly to the usable landscape. A nearly horizontal slope allows plants to take in water more effectively. On steep slopes water runs off readily, washing mulch, soil and plants with it. Raised beds, created by retaining walls, or containers need to be filled with planter mix or the original soil needs to have the addition of materials to approximate a planter mix. Extra organic matter in combination with pore-opening and water retaining roughage such as wood chips, isolite, hydrosource, etc. will aid in retaining water and promoting root growth.
Berms may also be a source of maintenance difficulties. Unless there is plenty of room constructing a berm may not be a good idea. We recommend no steeper than a four to one slope. That degree of slope is considered mowable. Each foot of rise takes up eight feet of horizontal space. Steep berms (greater than three to one slopes) have the same problems any steep slopes have- water runs off, mulch sloughs off, erosion occurs and plants may have a difficult time taking root. But weeds have little problem taking root on steep slopes.
The above are some of the maintenance issues of concern to landscape architects and designers. Designs that take these ideas into consideration should reduce both maintenance and water use in the landscape.
Gail Barry is co-owner of Land Mark Design Inc., a small landscape architecture consulting firm. She is a registered landscape architect, a long time member of ASLA, and has practiced in the Denver area for over 40 years.