Garden Assessment: Focus on Landform, Soil and Structures
Landscape problems to look for.
During our search for a new house last year, my wife and I developed a strategy when visiting potential properties. Carrie and our Realtor would go in the front door to evaluate the house while I toured the yard to assess the garden. As they reviewed the floorplan, bedroom count and storage space inside, my attention turned to the lay of the land, soil quality and the patio space outside.
Though I didn’t have time to complete a full site survey and analysis like I do at the beginning of a design project, there were a few quick appraisals I could make that told me if the garden stood in decent shape or needed work. After decades in gardens, I find this evaluation comes naturally, but it’s also something simple anyone can do. Whether you are assessing your landscaping after gardening on the property for many years or as a new homeowner, there are several important features to review above and beyond the prettiness of the plants. These include landform, soil and structures. Here’s how to do it.
Evaluate the Landform
Every garden assessment starts with a study of slopes, because these will affect the potential use of the outdoor areas and indicate how water moves through the property. Surface water runoff shapes a landscape, making proper drainage a key component in every garden. Large, complex properties may require a grading survey to understand the lay of the land, but most homeowners can see everything they need to know simply by observing the surface water.
First, check for poor drainage spots. I tell my design students to wait for a really rainy day and watch what happens. Puddles will form in low spots, but what’s important is to identify where the puddles persist. A low spot isn’t necessarily a problem if it drains in a few hours, but if standing water lingers in the planting beds, lawn, walkways or patio spaces, take note. Most plants, including turf grasses, suffer in saturated soil, and water can undermine stonework.
Examine the downspouts from roofs and gutters. Are they property attached? Does the outflow wash away soil or inundate nearby beds? Even worse, does it collect near the house where it may damage the foundation or get into the basement? Some drainage problems may require digging and installing drainpipes that carry the water away. If that’s the case, connecting all your downspouts to such a system is a smart investment.
Surface drainage fixes entail filling low spots with top soil and creating swales that direct water away from the house toward existing drains, streams, ponds, or open areas where water will soak into the soil. Hardscape may need to be reset to improve runoff, which provides an opportunity to install permeable patios and paths. These replace sealed surfaces with dry-set stone and gravel bases that allow water to infiltrate and disperse underground.
If you spot a problem area where water consistently collects you can also perform a perc test by digging a hole in the ground, filling it with water and observing how fast it soaks in. A percolation rate of 10 to 60 minutes per inch of water is considered adequate. Any longer and you need to think about re-grading the site or installing drains.
Evaluate the Soil
I use a catch phrase to demonstrate the importance of soil to my gardening students: “Soil is the foundation upon which all gardens grow.”
Like all maxims, it’s both obvious and true. Soil determines everything, from the success of a tomato crop to the beauty and bloom of perennial flowers to the longevity of your trees and shrubs.
There are two ways to approach soil. You can grow what it allows, or you can improve it so you can grow what you want. But before deciding your path, you need to know what you have. Start with a field test for texture.
Texture is an important attribute because it affects the soil’s ability to retain moisture and nutrients. Soils come in varying textures, from sandy to silty to clay, and every combination of the three. A well-balanced soil is called loam, though there are categories of sandy loam, clay loam and silty loam. The hope is that your soil doesn’t fall into one of the extremes—being too sandy or having too much clay.
You can perform a simple soil texture test in a matter of minutes. Simply grab a fistful from the ground in question and squeeze it tight. Open your hand. If the clump falls apart, you are dealing with sand. If it holds together, poke it. If it crumbles, that’s good news. Your soil is in the loam zone. If it doesn’t crumble, you’ve got clay.
Whatever the result, don’t fret. There are plenty of plants that like sandy soil, and clay is super fertile. Once you know what you’ve got, you can grow what will work or start improving your soil to expand your options.
In addition to feeling for texture, use your eyes and nose to inspect the soil’s quality. Besides the mineral particles of the soil which contribute to its texture, there are also organic components that provide the ingredients that bring your soil to life. Look for these. Bits of decomposing plants are good, as are thread-like fungi and tiny bugs or worms. These indicate that your soil is alive, with beneficial microorganisms present to promote the health and vitality of the ground you garden on.
Sniff your soil. If it smells rich and organic, that’s good. If it smells minerally, that’s all right too. If it’s stinky, that’s not so great. If your soil smells unpleasant and/or seems lifeless and sterile, the best way to improve it is to introduce compost, either storebought or homemade. Simply spread it an inch thick on any bare ground each spring. There’s no need to work it in. The active humus will infiltrate the soil after successive rains and start effecting improvements.
Evaluate the Hardscaping: From Pavers to Lighting
Hardscaping encompasses any material structures that allow for the practical use of outdoor spaces. This includes walls, walkways, patios, fencing, gates, decks, pergolas and arbors. It also includes practical items like water sources, lighting, planters and composters.
A garden’s usefulness hinges upon the character and condition of these features. Nothing last forever, especially material objects subjected to outdoor weather. Stones heave up, mortar cracks, wood rots and even plastic can degrade in time, so it is wise to evaluate your hardscape structures to get a sense of what may need repair or replacement.
The quality of materials used and the attention to detail during the construction of walls, patios and walkways is key to the longevity of these garden features. Moss and lichen as well as general weathering lends an air of established elegance to old stonework and should be preserved, but crumbling mortar and heaving step and patio stones must be repaired. More specifically, check for leaning walls and wobbly flagstones. For a proper walkway or patio, the stone used should be at least an inch thick, and wall stones must be solid.
Eliminate mortar altogether by replacing it with dry-set stone whenever possible. This allows for permeable patios that decrease lingering surface water or excess runoff and provides nooks and crannies to establish small plants.
Treated lumber and cedar, painted or not, will rot in time, but even more important is the type and condition of the hardware that holds it together. Screw fasteners are more secure than nails, but make sure they are galvanized or brass. Bare metal will rust and discolor the wood before it ultimately fails. Steel carriage bolts are even better, but should be treated with a black oxide coating, called bluing, to prevent rust.
Double check the footings of any wooden structures where the wood posts meet the ground. They’re typically set in concrete or fastened down with a metal bracket. Any wood in direct contact with the soil will be short-lived because the microorganisms in the soil—the same ones that break down your compost—will accelerate the decomposition of the wood.
There are many plastic composite materials currently available to replace outdoor wooden structures. They look like the real thing but they will never rot or require stain or paint. They’re also significantly more expensive than most natural materials, and they lack the organic look and feel that’s often preferred in garden structures. It’s up to you to make the aesthetic choice. For example, I’m okay with a composite fence along a far property line, but not close to the house.
Irrigation systems, if defunct or poorly maintained, should be shunned. The cost to upgrade, repair or replace the valves, lines and sprinkler heads will be matched by the frustration and hassle such work entails. Test each station to see if it works. If there are problems, be prepared to abandon the system and start fresh with more sustainable methods like rain barrels or switching to waterwise plantings.
A good garden also has a sufficient number of well-placed water spigots. Verify the location of these and make sure you have ready water where you need it, such as near a vegetable garden or container plantings.
Today’s landscape lighting is primarily LED technology running on low voltage wires that are easy to install and maintain. Older lighting typically relies on 120-volt lines running in conduit underground; it requires a licensed electrician to make any repairs. I prefer to abandon old lighting systems and install new low-voltage LED lights. Solar-powered lighting is an excellent option, but many of the fixtures available today are disappointing in their performance. Just like LED technology, they will continue to improve, but currently you can’t totally rely upon them for all of your lighting needs, especially safety and security.
