Drought Survival for Your Garden

By the Plant Information Specialists

·· Water-Wise Gardening ··


Drought Survival for Your Garden


In times of drought, limitations on the water supply usually go into effect. These restrictions can be challenging to the gardener. A Stage 1 Drought Emergency affects watering of landscape plants.

General Suggestions

Water conservation in the landscape is one way to help our natural resources last. Don't wait for restrictions on outdoor water use, or worse yet, an outright ban. You can begin now to assess and improve your garden so that it becomes far more "water-thrifty".

Site Inventory and analysis

To conduct a site inventory and analysis with water conservation in mind, determine what plants have a high water demand. Learn the prevailing wind directions, patterns of sun and shade, existing topography, and soil type on a site in order to improve growing conditions. Assess the condition and placement of your plants; do they conform to the principles of water use zones as outlined below? Note existing large expanses of lawn and ways to minimize these areas to some extent if possible.

Create Water-Use Zones

A well designed water-conserving landscape organizes the landscape into water use zones. Plants are re-arranged into three water use zones; high, moderate and low. Group water- demanding plants together close to the water source if they are spread out through the garden. The high use zone should comprise the smallest area, such as a planting near the front of the home, where ornamentals are easily visible and near the water source. The largest numbers of plantings should be in the low water use zone, where established plants need no supplemental irrigation. Drought tolerant turf grasses, woody ornamentals, and native or naturalized plants fit into this category. Moderate use zones would include plants that need to be watered as they show signs of drought stress.

Landscape to Conserve Energy

Environmentally sound landscape techniques include planting for energy conservation and microclimate improvement. For example, a house with southern exposure will benefit from the strategic placement of deciduous shade trees along the southwest corner, to lower the amount of heat and glare received on summer afternoons. Existing microclimates may be utilized to establish particular types of plantings; a garden in the shade is almost 20 degrees cooler than one in the sun. An area that recieves sun only in the early morning will tend to dry out less, as the overall transpiration losses will be lower.

Water Harvesting

Saving rainwater is a simple, water-wise idea. Connect downspouts from roof gutters to a plastic rain barrel equipped with a tap to save every precious drop of rainfall. The rain barrel will come with a top filtering screen to keep out leaves, twigs, and most importantly, mosquito larvae, which breed in standing water. Try to utilize this water as soon as possible to avoid larval breeding. To easily water your garden, attach a hand-held hose with shut-off nozzle to the barrel's tap.

Water Efficient Irrigation

Traditional sprinklers require high water pressure and waste almost 25-30% water due to evaporation and wind effect. Most existing water wasteful systems can be refitted with low-flow components to deliver water precisely where it is needed--- to the root area. With systems such as point/source drip, micro irrigation, drip line, and soaker hose, less water is wasted, uptake of nutrients and moisture is maximized and soil borne diseases can be reduced, as leaf surfaces are kept dry.

Water-Wise Horticultural Techniques

Planting

- Group plants together with plenty of room so their roots do not compete for water
- Reduce size of water-thirsty turf areas
- Introduce drought tolerant species
- Group plants according to their water needs

Watering

- Water newly planted trees and shrubs as they are most vulnerable to drought.
- Water early or late in the day to reduce water losses from evaporation
- Water thoroughly--deep watering encourages deeper rooting
- Water efficiently--low-flow watering delivers water precisely where it is needed

Maintenance

- Amend soils to improve drainage and water-holding capacity
- Use mulches to conserve soil moisture
- Keep weeds down as they compete for moisture
- Prune out all sucker growth, dead and dying wood and unwanted growth
- Incorporate more "hard" landscape features like patios, decks, fences, structures, etc. to reduce large expanses of a water-thirsty lawn

Further Suggestions

Designing for drought will help keep our green investments and natural landscapes alive. While some plant species are more xerophytic than others (better equipped to withstand dehydration), others have developed drought resistance by slowing down the growth process. Oak, black locust, ginkgo, callery pear, Kentucky coffee tree, and honey locust will slow growth considerably under drought conditions. Certain trees have little drought tolerance. These include katsura tree, shadblow, birch, mountain ash, yellow wood, and flowering dogwood.

Shrubs With Low to Moderate Water Requirements

Anthony Waterer Spirea Spiraea japonica "Anthony Waterer" Moderate
Bayberry* Myrica pensylvanica Low
Black Haw* Viburnum prunifolium Moderate
Broom Cytisus species and cultivars Low
Butterfly Bush Buddleja davidii Low
Chaste Tree Vitex agnus-castus Low
Rugosa Rose Rosa rugosa Low
Inkberry* Ilex glabra Moderate
Juniper* Juniperus species and cultivars Low
Korean Spice Viburnum Viburnum carlesii Moderate
Nannyberry* Viburnum lentago Moderate
Potentilla Potentilla fruticosa Low
Red Twig Dogwood* Cornus sericea Moderate
Shining Rose* Rosa nitida Low
Summersweet* Clethra alnifolia Moderate
Winterberry Holly* Ilex verticillata Moderate

Perennials and Herbs With Low to Moderate Water Requirements

Artemisia, wormwood Artemisia species and cultivars Low
Aster* Aster species and cultivars Moderate
Blanketflower Gaillardia species and cultivars Low
Black-eyed Susan* Rudbeckia fulgida Low
Butterfly Weed* Asclepias tuberosa Low
Coreopsis/Tickseed* Coreopsis lanceolata Low
Evening Primrose Oenothera fruticosa Moderate
Gayfeather* Liatris species Low
Lavender Lavandula angustifolia Low
Purple Coneflower* Echinacea purpurea Low
Rosemary Rosmarinus officinalis Low
Sedum Sedum species and cultivars Low
Sunflower Helianthus species and cultivars Low
Thyme Thymus species and cultivars Low
Yarrow Achillea species and cultivars Low

Annuals and Tender Tropicals With Low to Moderate Water Requirements

Cockscomb Celosia cultivars Low
Cosmos Cosmos bipinnatus Low
Creeping Zinnia Sanvitalia procumbens Low
Dusty Miller Senecio cineraria Low
Gazania Gazania cultivars Low
Geranium Pelargonium cultivars Low
Lantana Lantana camara Low
Marigold Tagetes cultivars Low
Portulaca Portulaca grandiflora Low
Zinnia Zinnia cultivars Low

* Indicates Native Plant

·· Water-Wise Gardening ··



Generous support for the Home Gardening Center has been provided by Kenneth and Ellen Roman.