Flower Management Before, During, and Following Drought

Agriculture at Colorado State University Cooperative Extensioin

Flower Management Before, During, and Following Drought

By Dr. Jim Klett, Larry Vickerman, and Carl Wilson Master Gardener,
Colorado State University,
Extension

If there are no watering restrictions:
The following practices will help keep your flowers healthy while conserving water.
- Proper soil preparation prior to planting will help conserve water. Prepare soil before planting by loosening soil to 12 inches. If it is a heavy clay or sandy soil, add two to three inches of compost on the soil surface and then till in to a 12-inch depth.
- Proper Mulch - Apply one to two inches of organic mulch between flowers to reduce evaporation and control water-using weeds.
- Fertilization - Fertilizing perennials is generally not needed if proper soil preparation is done prior to planting. Fertilizer causes lush growth that requires more water. If fertilization is needed, a slow release fertilizer can be applied in the spring.
  Moderate fertilization for bedding plants is recommended either as liquid or granular or a combination of both.
- Irrigation - Annual and perennial flowers under water stress will have drooping leaves and a lack of blooms. Foliage often appears gray-green in color. Water when signs of stress become obvious. Apply irrigation in the evening or early morning to minimize evaporation.
  Overhead spray irrigation is the least water wise method as much water is lost to evaporation and wind drift. Soaker hoses or drip irrigation are more efficient because they deliver water to the ground level near roots. Hand watering is another alternative that maximizes delivery of water to the soil and roots.
- Plant Selection - Some perennials are more efficient at utilizing water than others. Choose your plants to match the site conditions.
  Gray-leaved annuals and perennials are often more drought tolerant. Spring bulbs are drought avoiders as they complete their life cycle prior to the onset of hot weather.
- Some Drought Tolerant Annuals
  - Annual fountain grass - (Pennisetum setaceum )
  - Bachelor Button - (Centaurea cyanus )
  - Cockscomb - (Celosia plumosa )
  - Coreopsis - (Coreopsis tinctoria )
  - Cosmos - (Cosmos sulphureus )
  - Creeping zinnia - (Sanvitalia procumbens )
  - Cup Flower - (Nierembergia hippomanica var. violacea )
  - Dusty miller - (Senecio cineraria )
  - Gazania - (Gazania rigens )
  - Globe amaranth (Gomphrena globosa )
  - Johnny-jump-up - (Viola tricolor )
  - Mealy cup sage - (Salvia farinacea )
  - Mexican sunflower - (Tithonia rotundifolia )
  - Moss rose - (Portulaca grandiflora )
  - Periwinkle - (Catharanthus roseus )
  - Rocket Larkspur - (Consolida ambigua )
  - Rudbeckia - (Rudbeckia hirta var. pulcherrima )
  - Spider flower - (Cleome hassleriana )
  - Sweet alyssum - (Lobularia maritima )
  - Some Drought Tolerant Perennials Artemisias - (Artemisia species )
  - Blanket flower - (Gaillardia x grandiflora )
  - Blue fescue - (Festuca cinerea )
  - Creeping phlox - (Phlox subulata )
  - Creeping potentilla - (Potentilla neumanniana )
  - German Statice - (Goniolimon tataricum )
  - Globe Thistle - (Echinops ritro )
  - Hens and Chicks - (Sempervivum tectorum )
  - Ice plant - (Delosperma species )
  - Lambs ear - (Stachys byzantina )
  - Lavender cotton - (Santolina chamaecyparissus )
  - Little bluestem - (Schizachyrium scoparium )
  - Oriental Poppy - (Papaver orientale )
  - Ozark primrose - (Oenothera missouriensis )
  - Penstemon (Penstemon species )
  - Plumbago - (Ceratostigma plumbaginoides )
  - Poppy mallow - (Callirhoe involucrata )
  - Prairie coneflower - (Ratibida columnifera )
  - Prairie dropseed - (Sporobolus heterolepsis )
  - Purple coneflower - (Echinacea purpurea )
  - Russian sage - (Perovskia atriplicifolia )
  - Snow-in-summer - (Cerastium tomentosum )
  - Stonecrop - (Sedum species )
  - Yarrow - (Achillea species )
When watering restrictions are expected in the next few weeks, or if mild restrictions are in place:
- Annuals can be watered two to three times per week if approximately one inch of water is applied during each irrigation cycle. Water perennials deeply (one inch of water or more) two times per week during hot, dry periods. Water in the evenings or early morning to prevent evaporation loss.
- Mulching both annuals and perennials is critical to prevent moisture loss.
When no watering is allowed:
- Do not plant annuals when outside watering is not allowed.
- Do not plant new perennials; mulch existing plants.
After watering prohibition is lifted:
- Some perennials may not survive extended drought.
- Resume watering and check for signs of new growth that should appear in several weeks.
- Water perennials well in the fall and monthly during dry winters with no snow cover to ensure survival during the dormant season. Mulching the crowns of dormant perennials will prevent frost heaving and conserve moisture in the plant through the winter. For more information on dealing with drought conditions in Colorado, visit the Colorado State University Extension web site, www.ext.colostate.edu, and click on drought.

For more information on Gardening, contact your local Colorado State University Extension office.

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Updated Tuesday, November 27, 2007