Stretch your Water Supply with Beautiful Flowers – Robert’s Plant List for Rainwater

By author and guest blogger, Robert Kourik (more about Robert below!)


Buckwheat Flower


Spanish Lavender

Spanish Lavender

Indoor plants love rain water. The salts and minerals found in many water supplies, plus the chlorine, build up in the limited soil volume of the house plant pot—they can be seen as a white crust on top of the soil. Over time, chlorinated household water can even kill sensitive houseplants. For some gardeners, a rain barrel (or many!) connected to the home’s downspout is a must for watering indoor plants. But what about outdoors?

Outdoor plants also love rainwater. And it is best distributed with a drip irrigation system. The precious amount of rainwater you have collected should be stretched as far as possible. Some “droughts” in the country are only a handful of weeks. Other gardens have dry skies from June until October.

All gardeners can use the efficient distribution of water to make the best use of their stored rain water: drip irrigation saves up to 50% of your water compared to using a sprinkler. But planting the right plants is the first way to save you a lot of water.

Below I have included a plant list—a recommended plant palette for the water-wise garden. USDA plant hardiness zones are included to note species that are appropriate for different US climate regions.

Plant Hardiness Zone Map

The USDA’s Plant Hardiness Zone Map is an index of planting suitability in different US climate regions.

Some plants such as lavender (Lavandula spp. Zone 5-9), yarrow (Achillea millefolium, Zone 3-9), Powis Castle wormwood (Artemisia ‘Powis Castle’, Zone 6-9), Bearded iris, and New Zealand flax (Phormium spp., Zone 8-9) use 75 percent less water than lawn grass. Some other plants with a low water use (up to 70% less water than lawn grass) include*:




Aloysia triphlla Lemon Verbena 8-9
Aquilegia Columbine 4-9
Artemisia spp. Various names (includes Wormwood) 6-9
Coreopsis spp. Coreopsis 4-9
Erigeron karvinsklanus Mexican Daisy 4-9
Eriogonum spp. Buckwheat 6-10
Eriogonum grande rubescens Red Buckwheat 8-9
Euphorbia spp. Euphorbia 7-10
Gaillardia x grandiflora Arizona Sun Blanket 5-9
Gypsophila paniculata Baby’s Breath 4-9
Helianthemum nummularium Sun Rose 4-10
Iris douglosiana Pacific Coast Iris 6-10
Lantana spp. Lantana 7-11
Limonium perezii Sea Lavender 9-11
Linaria alpina Toadflax 4-9
Lobelia laxiflora Mexican Lobelia 9-11
Mentha piperita Chocolate Mint 8-9
Nepeta fassnell Cat Mint 3-9
Oenothera spp. Primrose 4-9
Osteospermum spp. African Daisy 9-11
Salvia corrugata Corrugated Sage 9-11
Salvia spp. Salvia (Check your local nursery) 3-9
Santolina chamaecyparis Santolina 7-9
Sisyrinchium californicum Blue-Eyed Grass 3-9
Stachys byzantina Lamb’s Ears 4-9
Tagetes lemmonii Copper Canyon Daisy 9-10
Verbena spp. Verbena 5-10

Once you’ve planted, set up your drip irrigation

Inline Emitters

Drip Irrigation with Inline Emitters

Drip irrigation is not only water efficient, it also promotes increased yields of fruits and vegetables. The use of drip can usually increase yields by at least 20%. In one case, with chilies, the drip system saved 38% of the water and increased yields by 48%. For row crops (i.e. vegetable gardens!), use in-line emitter tubing with emitters installed every 9 – 12 inches. In-line tubing has an emitter built inside the tubing so there is nothing to snap off.

For perennial gardens with irregular plant spacing, use custom-punch emitters. These will allow you to better control the amount of flow to each plant.

To use drip irrigation with your rain water:

  • Store as much as you can. Consider a large cistern, or a multi-barrel system to save space.
  • Use a 100-micron filter between your rain barrel(s) and drip line or soaker hose. Otherwise emitters and pores will clog.
  • Place the 55-gallon drums as high as possible above the drip tubing. Or, add a booster pump for good water pressure.
  • Keep the filter clean at all times. Use a toothbrush and bleach as necessary.
  • Flush the drip hose once a year when it is raining to get any dirt out.
  • In cold climates, store the filter indoors and drain the tubing.
  • Water in the evening, making sure no foliage gets wet.
  • Place the emitters about six inches from the base of the established plant.
  • Use no more than 30 feet of drip irrigation hose per connection.
  • For soaker hoses, use a specialty rain barrel soaker hose designed for non pressurized water sources – they have a special porosity ratio.

I wish you happy gardening!





Does Robert Kourik really know his stuff when it comes to sustainable gardening? Well, just ask the experts: Sunset Magazine described his Drip Irrigation book as “The last word on [the subject]” and “infused with good humor.” Businessman, author and environmental activist Paul Hawken describes Robert’s work as “uncommonly valuable.” To see the 15 books Robert has written on topics like roots, grey water, lavender, edible landscaping and no-till gardening go to


*Source: Water Use Classifications of Landscape Species (WULCOLS) report.


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