Location and Microclimates
Your location may determine certain design, style and plant choices you make. Take time to study your location at different times of day. Ideally, it would be best to study the effects of weather within the landscape through the seasons. Each location can contain many microclimates, or micro niches. Climate is the compilation of weather events for a long period of time for a wide area. Plant’s survival often depends more on its exact placement in relationship to features surrounding it than to the climate. Unless you have a flat plain with no trees, buildings, walls or boulders, you will have a variety of microclimates to work with.
Temperature and Wind
If you plan to landscape your home, you will have areas sheltered or exposed to the wind. You will have shade and sun areas. If your home is brick, and faces south, you have a microclimate up to a ½ zone warmer (5 degrees) than an exposed site on the north side of the home. Add this to another ½ zone difference for living in the city (as opposed to living in the country). Sloping areas that end in a swale will be moister; soil at the top of mounds will be drier and if amended, provide better drainage. What this means to you as a gardener, is that you will be able to increase your plant palette by thoughtfully placing plants in the proper microclimate. Thoughtful placement also lowers your maintenance effort and time.
Water Runoff, Slopes and Swales
Sloping landscapes offer advantages and challenges. Plan to use it to your advantage, not as a challenge. A slightly sloping yard gathers water at the bottom, a natural gathering point for moisture loving plants. When the slope ends in a sidewalk or street, the water runs off into that, unless you capture it first. Roof runoff aids in the water needs for high and medium water-use plants. I rarely water the landscaping on the west side of my house, where I’ve put a path, shrubs and groundcovers. Our rainfall provides adequate moisture most of the time for my low and medium water-use plants (already established).
Instead of using roof runoff naturally, you may decide to install rain gutters and a water catchment system. Approximately 600 gallons of water can be harvested from inch of rainfall over a 1000 sq. ft. area. Catchment systems have 3 main components: the gathering area (rooftops being the most common, driveways or slopes), the gathering system (rain gutters, downspouts, channels, canals, dry river beds; filters and the storage tank or barrel) and the distribution system (spout and watering can, hoses, pipes, pumps or a tie into an irrigation system).
If your yard is more steeply sloped, a series of terraces correct this problem, adding visual interest at the same time. A rock garden, similar to an alpine rock garden, is one style that’s ideal for slopes. Or cut wider terraces composed of medium or low water-use plants. Ornamental grasses or xeric groundcovers help anchor the soil. Slopes with fescue and bluegrass lawns require even greater amounts of water.
For lower maintenance slopes, choose a different groundcover if you choose not to terrace. Vinca major and minor and Cerastostigma plumbaginoides, hardy blue plumbago are some traditional choices, Callirhoe involucrata, winecups, Oenothera speciosa and O. berlandiera, Showy and Mexican evening primrose, are native choices for groundcovers. Like the vinca, they are not good choices mixing them within flower beds, but by themselves, as they will out compete most plants. Veronica pectinata, wooly veronica, V. pectinata ‘Rosea’, V. ‘Blue Reflection’, Thymus ‘Ohme Garden Carpet’, ‘Reiter’, ‘Pink Chintz’ are a few adapables to use that are not as aggressive, but still good spreaders.
Hydro-Zoning and Water-use Defined
Grouping plants together in the landscape according to their water needs is referred to as hydro-zoning. Siting your hydro-zones properly in your landscape is one of the most effective ways to use your microclimates. Basically, plants are grouped together in high water, medium water and low water-use zones. All plants need a certain amount of water for survival. This varies from plant to plant, and varies with soil and weather/climate conditions. As you gain experience with your chosen plants, soil and micro niches, you can finesse the placement of the plants to minimize your irrigation maintenance. Just the addition of an accent rock or slight mounding in xeric beds creates pockets of moister areas (close to rock and in lower areas) and dryer conditions with better drainage (top of mound).
Typically, high water-use plants are grouped together close to the water source. Medium water-use plants are placed a little further out and low water-use plants are located the furthest out. There are, of course, native plants that require no irrigation, once established. Hydro-zone these as well, or mix them with low water-use plants and they’ll perform better for you in the garden setting than in nature.
High Water-Use Plants
I classify high water-use plants as plants that require 1 inch of water weekly under average summer growing conditions. Fescue and bluegrass lawn grasses fall into this category. Plants typically grown in the Northeast, Southeast and Pacific Northwest and many tropical plants fall into this category, as a general rule. Native plants that originate in riparian regions may also be high water-use.
Landscapes that incorporate the xeriscape principles with an emphasis on water conservation can contain plants of all water needs. For greater water conservation, just limit the area devoted to high water-use plants. Bluegrass and fescue lawns are high water-use plants. It is recommended to limit high-water-use lawn areas to a third of your landscape. You don’t have to deny yourself the pleasure of these plants unless your water supplies are limited.
Other favorite high water-use plants can be grown in containers and pots, or in shady, moister corners of your garden. Vegetable gardens are high water-use plants. Water can be conserved by the use of well amended soil, mulch, drip and/or emitter irrigation and row covers. If water is limited, catch, store and use rooftop rainwater. Or practice spring, fall and winter gardening (use poly tunnels to cover winter-vegetables) to reduce the use of water.
I grow colocasias, alocasias (elephant ears) and caladiums each year in containers and at my front entry, a 4’ x 6’ bed. It receives roof runoff and is shaded for all but a few minutes each day. I’ve amended the soil well for organic content. A few minutes of watering whenever I water the containers is all that’s needed to sustain this lush subtropical foliage.
Medium Water-Use Zones
Medium water-use plants are plants that need to be watered every 2, or 3 weeks, depending on the plant. Medium water-use plants are native to the mid and tall-grass prairie areas of the Great Plains and south and southeast Texas and other areas receiving 25 inches and more of rain. Use this as a general guide. Our climate is similar to the Great Plains, but not exactly like it. Our soil has less organic content. We are hotter, less humid and receive less rainfall, but many of the weather conditions are similar. Plants that have adapted to those regions will adapt to our region with proper soil amending and irrigation.
Some better known examples are agastaches,rudbeckias (black-eyed Susans) echinaceas (other than our native Echinacea angustifolia), many salvias, heucheras (coral bells), geraniums, gaura, scabiosa, dianthus, campanulas, many non-hybrid tea roses, some ornamental grasses and most of the traditional shrubs we’re familiar with. In fact, many shrubs and ornamental grasses, if planted in well-amended soil and established, can actually be considered low water-use. Many trees adapted to our area fall into the medium water-use category, once established (however, trees require irrigation that is less frequent, but longer).
Low Water-Use Zones
Low water-use plants are plants that require an inch of rainfall or irrigation a month during the growing months under average conditions. Plants that originate in semi-arid, cold desert and in higher elevations in the southwest (and other similar eco-regions of the earth) with alkaline clay and caliche soil and little organic matter do very well in our area. You many find it surprising how many beautiful plants this category comprises! When they are brought into the garden setting, with soil amended for drainage and with no more than 3 inches of organic matter, they perform beyond our expectations and bloom longer than they do in native conditions on their own.
The recommendations for supplemental irrigation are based on soils that have been amended for that category of plant, high, medium and low feeders, and the soil is amended for the plant’s requirements of soil drainage.
Some of our local native plants are Calylophus, sundrops, Engelman’s daisy, Scutellaria, skullcap, Melampodium leucanthum, Blackfoot daisy, Berlandeira lyrata chocolate flower, gaillardias, blanket flowers, Ipomea leptophylla, bush morning glory, Oenotheras, Penstemons and Zinnia grandiflora, prairie zinnia. Other native and non native plants (to the Texas Panhandle) that are adaptable to our low water-use areas are Origanum libanoticum, hop, or Lebanese oregano, Anisicanthus wrightii quadrifidius, flame acanthus, Salvia greggii (Zone 5 or 6 for us), cherry or autumn sage, S. chamaedryoides, germander sage or New Mexican Blue Sage, many sedums, Veronica pectinata and V. ‘Blue Reflection’, Artemisia versicolor, ‘Sea Foam’, Marrubium rotundifolia, silver edged horehound, Caryopteris, blue mist spirea, Nepeta faassenii ‘Select Blue’, a catmint variety, Centranthus ruber coccineus and alba, Jupiter’s Beard, and Cerastostigma plumbaginoides, hardy blue plumbago to name a very few.
These watering guidelines are for average weather conditions in the Texas Panhandle. Our highest average maximum high temperature is 91° for July and August. Conditions more extreme (hotter than 93° over several days) may require more water for all types of plants. Gardening is about enhancing the appearance of the plant over how it would appear in nature, it's about thriving, not just surviving. Gardening is about giving care according to the needs of the plants. From season to season, year to year the amount of care required may vary, depending on conditions.