Why Rockscapes Aren't All They're Cracked Up To Be
Posted on: Tuesday, November 12, 2019
Why It's Time To Let The Landscaping Rocks Roll
Almost year round, but especially during the summer, we’re looking for ways to keep our homes and yards more comfortable without breaking the bank on air conditioning and water bills. Smart landscaping choices can help keep you cool both inside and out.
Hardscaped Landscaping Is Hotter Than You Think
It can be tempting to cut down on your water bill by landscaping entirely with hardscape features like boulders, crushed rock or rock mulch and artificial turf. However, you’ll likely offset those savings with an increase in your air conditioning. These landscaping features can actually increase the temperature of an area – absorbing heat from the sun and releasing it into the surrounding areas both day and night.
If you do have organic softscape features (plants), the extra heat released from the rocks increases plant respiration rates, meaning a plant could use food faster than it could make it. This is especially true for non-native plants not adapted to Arizona’s hot, desert conditions.
If you intend to use rocks as ground cover, avoid placing them next to your house on the south or west side to avoid excess heat from being released into the home. We also recommend incorporating fifty percent shade over the top of your rock ground cover by planting heat-tolerant trees, shrubs, ground covers and other types of plants.
Artificial turf is another popular option for reducing landscape water use and can make a good alternative in small areas like parking lots or street-side beds. However, it also absorbs heat and will increase the temperature in the immediate area. In fact, it often becomes dangerously hot to bare feet if exposed to direct sunlight - making it a poor choice for patios and play areas and something for pets to avoid as well!
Preparing an area for artificial turf requires excavation and the addition of added base materials and soil compaction, which can damage and inhibit the healthy root growth of plants that are in your yard.
Benefits of Softscaped Landscaping
Real turf/grass, meanwhile, helps cool the area as it releases water into the atmosphere through evaporation. Other softscape features like shrubs, vines, groundcovers and trees can also help cool things down and reduce the load on your air conditioner.
Beat the Heat Buildup
Energy-efficient landscaping requires a little bit of basic knowledge about how heat moves through your home. Walls, windows, roofs and glass doors all absorb the sun’s radiant heat and bring in hot outdoor temperatures through conduction or infiltration. Shading your property with trees and shrubs can slow that exchange of hot air for cool by cooling outdoor surfaces and reducing the rate at which they absorb heat.
A tree’s growth rate, and the shape and density of its canopy, determine its shade value and potential energy savings. A fast-growing tree may offer shade faster but is likely to be less hardy than a slow-growing counterpart. Look for trees that produce a dense canopy with multi-directional branches and light-colored, smooth leaves. When you plant it, make sure to take into account the size it will be at full maturity, and the amount of space needed to develop a healthy root system.
Plant shorter trees or taller shrubs along the sides of your home to deflect the afternoon sun away, and take advantage of the cooling effect they can have on the ground around your home. Training hardy vines to grow on vertical trellises along your home’s exterior also helps deflect the sun and prevent the walls of your home from absorbing heat.
Encourage Cool Breezes
The same trees and shrubs that provide shade during the day can also help guide cool evening breezes during the times of year when it’s comfortable enough to open your windows at the end of the day. Since air moves most quickly in the air beneath the lowest branch and the ground, prune to circulate air toward your windows. Shrubs planted underneath windows and near those trees also help to channel air up and into first-story windows. Prune a small gap between the shrubbery and the walls of your home to prevent moisture buildup and reduce humidity.
Landscaping With Softscape Features In Poor Soil
Softscaping your lawn or rockscape to help keep your yard and home cooler only works if the plants can grow and thrive in your local soil. If your yard is primarily made up of sandy, rocky, shallow soil lacking in nutrients you’ll either need to do some serious soil amendment, or consider installing planters that are filled with a pre-mixed soil.
Raised Beds vs Basins
There are two different types of planters to consider when you’ve decided to create a growing medium from scratch, and they are raised beds and basins. Like their names describe, raised beds are boxes that are built directly on top of, or elevated above, ground level, while basins require digging into the earth to a set depth and creating a space that will sit flush with the rest of your yard when complete. Here are some insights from a few of the master gardeners just south of us in Pima County on the pros and cons of each.
Basins definitely have the advantage here. It’s a lot cheaper to dig into the ground than to purchase the container material and soil to fill it, on top of the labor required for physical construction. You can save money and reduce weight by partially filling it with gravel or biodegradable packing peanuts, but the change in texture can create an underground water table that will rot roots and limit the physical space for growing roots. Basin gardens will also need amended soil, but you can reduce that cost by mixing in some of the native soil that you initially removed.
Here’s where raised beds bounce back a little. Especially for new gardeners, a raised bed is ready for planting immediately after being completed. Set up the bed, toss in your dirt and you’re ready to go.
Basins, meanwhile, require digging at least a foot down into your yard which is time-consuming and difficult in places like the foothills where gardeners may encounter large rocks and cement-like caliche. In the valley areas, much of the soil is clay and silt which is easier to dig through.
Raised beds are a boon for gardeners with accessibility needs. They can be customized so that little to no bending or kneeling is required to work on your plants. However, raised beds do need to be narrow enough that you can reach the middle of the bed, and the gardening area is limited to the physical size of the container.
Basins can be as large as the space you are able to dig. Since they are at ground level gardeners are able to physically walk among the plants and don’t have to reach from a border. However, be aware that walking over the soil too frequently can cause compaction and inhibit root growth.
4. Plant Care
Basins are able to take greater advantage of flood irrigation and rainwater, which keeps the soil moist longer and can reduce the frequency of needed watering. How quickly the soil in raised beds dries out depends on what the raised bed is made out of. Cinder blocks hold water well, but woods and plastics/resins do not.
When it comes to protecting your edible plants from falling victim to the local wildlife, ground-level basins are more vulnerable. It’s a harder climb into raised beds, especially if you are using a smooth-sided container like a metal tub.
Another big cost for raised beds includes maintenance, especially preserving or replacing wooden frames.
If soil in raised beds or containers becomes diseased with fungus or other plant-killing conditions, all of the soil will need to be replaced. In-ground beds, on the other hand, will only need the spot where the problem is occurring to be replaced.
Both raised beds and basins will need soil amending before every planting season to make sure enough nutrients are available.
While basins are basically a giant hole in the ground, raised beds can be customized with colors, textures and architectural features.
So Which Form of Landscaping Is Better?
Ultimately, the master gardeners say, it comes down to the gardener. Both types of beds work well in local conditions, so whichever is more likely to get you out into the garden.
Of course, you should also consider which plants you’ll be growing, and how long you plan to keep them around. While small edibles and annuals are perfect for a raised bed, that shade-producing tree and row of hedges are better suited for a basin where it can stretch its roots and become an established and permanent part of your landscape.
Ask The Gardening Experts
Still need some help figuring out what works best for your lawn, groundcover and landscape desires? Stop in to any one of our three Valley locations and talk with one of our Trusted Garden Advisors about your unique yard. We’re happy to make recommendations from the ground up.