Water-Wise Garden Zones: What plants go where?
Many plants can be considered low water use or water-wise, but not all low water plants have the same watering requirements. Choosing the right plant for the right spot can be challenging. In this guide we provide valuable information to help you make good design decisions. Knowing what type of plants to plant where can be the difference between achieving planting success or experiencing an utter plant failure. It is just a fact of nature that not all plants can be happy everywhere, although many plants can perform well if they are planted in a location that suits their evolutionary parameters and tolerances.
Note: In this blog article, we are not talking about USDA Hardiness Zones. Those are guidelines based on the average lowest temperatures typical to your region according to elevation, latitude, and other factors.
Water-Wise Zones represent the different moisture & exposure zones that occur on a property or in your yard. There are 3 typical xeric zones to consider when you are choosing plants for low-water landscapes.
- Zone 1 – Oasis
- Zone 2 – Transition
- Zone 3 – Xeric/Hot Zone
Most landscapes consist of one or more of these different zones based on things like:
Sun exposures (north, south, east or west), reflected heat, surfaces, etc.
Planting proximity to the house, structures, hardscape, or other natural features.
Any existing shade trees, large natural shrubs or other competing plants.
Topography of the property or site, soil composition, natural swales/berms, etc.
Some yards and landscapes have more complex planting zones than others, when considering all of these factors, but these 3 basic zones provide a good guideline to help you to form a plan, design a functional garden, and achieve a properly planted water-wise landscape, no matter where you live currently.
The descriptions and explanations of these zones should help you choose the right plant for the right place in your garden or water-wise landscape. The info and suggestions here are generalizations, but should give you a good guide & platform of knowledge to start from.
Zone 1 – Oasis Zone
Oasis zones are those areas where more soil moisture is available or typically lingers in the soil longer. In low or inland deserts these are often dry shade as well. Think of a shady grotto. These areas are typically shadier, less exposed, and usually nearest to the house, especially at entryways, around patios, decks, or beneath windows. Even in hot climates, shady areas dry out slower and therefore require less frequent waterings. Oasis zone plantings are typically lusher looking due to the plants that work well here, which is pleasing in hot, dry climates, but these plants can require more maintenance and attention depending on how elaborate the design is. Because of this, designers often forego using a high number of oasis zone plants and instead opting for lower maintenance transition zone (Zone-2 below) plants in the spaces near the house or shady spots.
Zone 1 example plants:
Ornamental grasses, flowering native or adapted perennials, evergreen groundcovers, bulbs, tuberous plants like Manfreda, Mangave hybrids, Lilies, Saliva sp., small ornamental trees, small palms, well-behaved accent plants, succulents, various non-native potted plants, etc. Too many good options to list them all here. TIP: Remember, sun-loving perennials don’t flower well in shadier spots, so choose shade tolerant flowering perennials for Oasis zones such as Aquilegia sp., Mimulus sp., Bulbine sp., Aloe sp., Verbena sp., Tradescantia sp., Agapanthus sp., Jasminum sp.
Zone 2 – Transition Zone
Transition zones are basically the middle areas between zone 1 & 3. Think of a semi-arid steppe. These spaces are generally more open and exposed but can get some shade during the day from trees, the house, a building, or other structures. There can be natural, but beneficial topography such as berms & swales in the transition zone compared to flatter areas directly adjacent to the house as well as hardscape features to design around. Depending on the site and sun exposures, some transition zone areas may include spots next to sidewalks, driveways, or perimeter fencing, etc. Site visits and some daily observations should dictate whether zone 2 transition zone plants or zone 3 hot-zone plants should be used.
Zone 2 example plants:
Low-water use native Chihuahuan, Mohave, or Australian native shrubs do well in this zone, as well as some Mediterranean and South African specie. Low-water use ornamental grasses, most western native flowering perennials, adapted evergreen & deciduous shrubs, sub-shrubs, ground covers are all valuable options for this zone. Medium to large adapted shade & fruit trees, and large fruit bearing shrubs should be planted in this zone. Medium to large (arborescent) Yucca sp., Nolina sp., Agave sp., and non-native cacti or succulents also do well in transitional zones.
Zone 3 – Xeric/Hot Zone
The xeric zone is the hottest, most exposed zone. Think, true desert areas. These zones occur mostly around the perimeter, edges and rocky high spots of a property. Sun, wind, and reflected heat are prevalent most days which translates to perpetually dry soils and heat. In the xeric zone caliche & alkaline soil characteristics are the norm, especially in low desert environments. In mid and high desert environments soil drainage is typically better, but soils still tend to be alkaline (pH 7.1 – 8.5). The good news is that most native & adapted plants can tolerate these exposure elements and can usually tolerate low water, poor drainage situations once they are established. Berms & swales can be designed in and engineered to form natural water catchment areas, but all-in-all these are dry, exposed areas. Plants in zone 3 will still need to be on supplemental irrigation, especially during establishment, but it can be reduced to more minimal amounts once the plants are established. Establishment is variable depending on the species, but you can expect a range of 6-18 months from planting for most native or regionally adaptable shrubs, trees and accent plants. Perennials typically take less time.
Zone 3 example plants:
Low to mid-desert native flowering shrubs, native perennials or ephemeral wildflowers, native cacti species, Yuccas, most Agave sp., several types of succulents, Dasylirion sp., Hesperaloe sp., small native tree species like mesquite, desert willow, and some varieties of Acacia can do well. In high desert areas that have colder winters, seek out true native shrubs, grasses, perennials and small native trees. Some yucca species and Agaves may work fine depending on your location. Ask us for suggestions.
Final thoughts and Words of wisdom
Yes, even water-wise plants need water to thrive, especially when they are first starting out. The trick is to water them enough to be healthy and become properly established, before you can start weaning them off to a lower sustainable amount of water. Remember, in the nursery, plants in containers get watered regularly to grow and look their best, so that is what they will need for a while after planting. Don’t plant into a dry hole. Add water to hydrate the surrounding soil profile just prior to planting, especially when the sun is intense and temperatures are already high.
For most woody shrubs & trees, it takes about 6-8 weeks to start growing new roots, this is the most critical period of time for them. Most perennials can start growing new roots in 2-4 weeks, but full establishment can take 6-8 weeks or longer, depending on the species. The hotter and drier the weather, the more difficult this growth transition is, so be diligent and consistent about providing water for your new plants. Keep in mind, if the soil has adequate & appropriate drainage, it is difficult to overwater new plants, especially in spring and summer when daytime & nighttime temperatures are high. TIP: Lower mature leaves turning yellow is one typical sign that the roots are staying wetter than they like and you should allow more time between waterings or adjust the watering schedule accordingly to avoid root rotting or eventual plant death in this scenario.
As with all our Plant Care blogs, if you have further questions or need additional information regarding this guide, please don’t hesitate to reach out to us directly: happyvalleyplants@gmail.com
Watch for our next blog: Soil Matters for tips, recommendations and details about preparing and providing the proper soil for your low-water use plants.
**Blogs & photos by Daniel S. Goodspeed, without use of AI. No photos or blog info may be reprinted or reproduced without permission or consent of the author, Happy Valley Plants™ or its subsidiaries. **
