Water-Wise Garden Zones: What plants go where?
Many plants can be considered water-wise or low water use, but not all low water plants have the same moisture 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 acheiving planting success or experiencing an utter plant failure. It is just a fact of nature that not all plants can be happy everywhere.
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), planting proximity to the house, misc. structures, hardscape features, any existing shade trees or other large natural shrubs, and the general topography of the property or site. Some yards and landscapes have more complex planting zones than others based on all these factors, but these zones provide a good guideline to help you form a plan and design a garden or landscape from. The descriptions and explanations of these zones should help you choose the right plant for the right spot in your garden or water-wise landscape.
Zone 1 – Oasis Zone
Oasis zones are those areas where more soil moisture is available. 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, shadier areas dry out slower and therefore require less frequent waterings. Oasis zone plantings are typically more lush looking, which is pleasing in hot, dry climates, but these plants do usually require more maintenance and attention depending on how elaborate the design is. Because of this, designers will often forego using a lot of oasis zone plants, instead opting for lower maintenance transition zone plants in the spaces near the house. (see Zone-2 below)
Zone 1 example plants:
Ornamental grasses, flowering perennials, evergreen groundcovers, bulbs, tuberous plants like Manfreda & hybrid Mangaves or Canna lily, Saliva sp., small ornamental trees, small palms, well-behaved accent plants, succulents, various non-native potted plants, etc.
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, or the house. There may be beneficial natural 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, the transition zone may include areas next to sidewalks, driveways, or perimeter fencing, etc.
Zone 2 example plants:
Most low water use Chihuahuan, Australian or southwestern native shrubs do well in this zone, as well as some Mediterranean plants, ornamental desert grasses, western native flowering perennials and sub-shrubs/ground covers. Medium to large shade & fruit trees, and large fruit bearing shrubs need to go 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 of a true desert. These zones occur mostly around the perimeter, edges and rocky high spots of a property. Sun, wind, and reflected heat are prevalent which translates to perpetually dry soils. 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 not as severe, but soils will 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 create 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 minimal amounts once the plants become mature which takes approx. 12-18 months from planting.
Zone 3 example plants:
Low 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 mid to high desert areas look for true native shrubs, perennials and small native trees.
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. For most woody shrubs and trees, it takes about 6-8 weeks to start growing new roots, this is the most critical period of time for them. 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. If there is adequate drainage, it is difficult to overwater new plants, especially in spring and summer when daytime temperatures are high. TIP: Lower, more mature leaves turning yellow is one typical sign that the roots are staying wetter than they like and you can allow more time between waterings.
NOTE: If you would like more detailed suggestions of plant varieties for these specific landscape zones or have other additional questions, please email us: 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.**
