Conservation in Full Flower: How to Garden with Less Water

By Chrislyn Johnson

I love gardening and the beauty that annual flowers bring to a landscape. I also like to think of myself as being environmentally conscious. However, these two pursuits are not always in harmony when it comes to gardening if I want to conserve water.

Humming Bird and FlowersFlowers in the Heartland take a lot of water, especially annuals (which grow only one season). Once they are established, most annuals need about one inch of water per week, or half a gallon per square foot of garden space. That may not sound like a lot, but it adds up quickly. A typical garden 25 feet long and 4 feet wide along the front of your house will consume at least 25 gallons each week. Over the course of a growing season, that adds up to more than 750 gallons of precious water!

The reason annuals need a lot of water is based on their very nature. They have shallow root systems and spend their time and energy repeatedly blooming all summer. From the annual plants’ point of view, they have one chance to successfully produce viable seeds for the next year, so they don’t waste time in the growing phase. They will instead put their energy into producing big, showy flowers all summer long. Annuals need varying amounts of light and care to produce these beautiful blooms, but most tend to be sensitive to the amount of water they need.

There are four major factors that determine how much to water annuals, according to About.com:

  1. Weather: The heat, wind, rain, and humidity of their location all affect how well your plants will grow without added water. A plant in a hot, windy, and very sunny location will require more water than the same one in a partially shaded spot. The plant in the sunny location may receive rain, but if the soil is hard, it might not soak in. Plants need moisture at least 2-3 inches below the soil’s surface. Watering in the morning or evening provides the most benefit and retention. To keep this moisture from evaporating, many experienced gardeners use mulch, which has the additional advantage of keeping weeds out and making flower beds more attractive. Think about the conditions of where you are putting your plants and what that might mean for their care.
  1. Soil Quality: The type of soil you have – deep and rich loam, sandy, rocky, or clay – will make a difference in the amount of water your plant needs. While sandy soil drains well, it does not hold much water. Soil with a lot of clay can present other problems: it can hold too much water and cause your plants to rot, or it can be so dry that it is impenetrable to rain that just runs off the surface. The solution to most soil problems is adding organic matter such as compost, rotted manure, or aged grass clippings or leaves (leaf mold). Work 2-4 inches of organic matter into the top 8-10 inches of soil. Do this each year, because the organic matter will continue to decompose and is used up by the plants and organisms that live there.
  1. Ground or Container: Where plants are grown makes a difference. Your plants will need lots of water until their root systems are established. Container plants are best used for accents, since they will generally continue to need more water and care than their counterparts in flower beds, but this again depends on the other factors mentioned here.
  1. The Chosen Ones: The plants you choose will go a long way to decreasing the need for extra water usage. Traditional favorites add charm and are more drought-tolerant than many of the newer varieties. The bonus with these tried and true alternatives is that many grow directly from seeds that you can save from one year to another. So not only do you save water, but you also save money!  Below is a list of alternatives to the typical, water-loving garden center choices, many of which also make excellent cut flowers to bring indoors.
Common Name Scientific Name
Ageratum Ageratum houstonianum
Angelonia Angelonia angustifolia
Blanket flower Gaillardia pulchella
Calendula Calendula officianalis
Cockscomb Celosia cristata
Coleus Coleus spp.
Cosmos Cosmos bipinnatus, Cosmos sulphureus
Creeping zinnia Zinnia linearis
Dusty miller Senecio cineraria
Flowering tobacco Nicotiana alata
Foxglove Digitalis pupurea
Gazania Gazania splendens
Geranium Pelargonium x hortorum
Globe amaranth Gomphrena globosa
Madagascar periwinkle Catharanthus roseus
Marigold Tagetes erecta, Tagetes patula
Melampodium Melampodium paludosum
Moss rose Portulaca grandiflora
Ornamental kale Brassica oleracea
Ornamental pepper Capsicum annuum
Pansy Viola x wittrockiana
Petunia Petunia x hybrid
Salvia Salvia slendens, S. facinacea
Snapdragon Antirrhinum spp.
Statice Limonium spp.
Strawflower Helichrysum bracteatum
Sweet alyssum Lobularia maritime
Verbena Verbena spp. and hybrids
Wax begonia Begonia semperflorens-cultorum
Zinnia Zinnia elegans, Z. angustifolia

Does it seem like a big task? You don’t have to give up all of your favorites now. Just try a few of these and see what you think. Lean into the change at a pace that is comfortable for you, and you may find that you appreciate spending less time watering and more time just enjoying your garden.

About the Author: Chrislyn Johnson is a Life Scientist with EPA Region 7’s Water, Wetlands, and Pesticides Division. She holds degrees in biology and photography from the University of Central Missouri and loves all things nature. She is frustrated by clay soil.

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is www.epa.gov. Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.